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2020-08-29Merge tag 'for-linus-5.9-rc3-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fixes from Juergen Gross: "Two fixes for Xen: one needed for ongoing work to support virtio with Xen, and one for a corner case in IRQ handling with Xen" * tag 'for-linus-5.9-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: arm/xen: Add misuse warning to virt_to_gfn xen/xenbus: Fix granting of vmalloc'd memory XEN uses irqdesc::irq_data_common::handler_data to store a per interrupt XEN data pointer which contains XEN specific information.
2020-08-27xen/xenbus: Fix granting of vmalloc'd memorySimon Leiner
On some architectures (like ARM), virt_to_gfn cannot be used for vmalloc'd memory because of its reliance on virt_to_phys. This patch introduces a check for vmalloc'd addresses and obtains the PFN using vmalloc_to_pfn in that case. Signed-off-by: Simon Leiner <simon@leiner.me> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/20200825093153.35500-1-simon@leiner.me Signed-off-by: Juergen Gross <jgross@suse.com>
2020-08-23treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-07-11Merge tag 'for-linus-5.8b-rc5-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fix from Juergen Gross: "Just one fix of a recent patch (double free in an error path)" * tag 'for-linus-5.8b-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/xenbus: Fix a double free in xenbus_map_ring_pv()
2020-07-10xen/xenbus: Fix a double free in xenbus_map_ring_pv()Dan Carpenter
When there is an error the caller frees "info->node" so the free here will result in a double free. We should just delete first kfree(). Fixes: 3848e4e0a32a ("xen/xenbus: avoid large structs and arrays on the stack") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Link: https://lore.kernel.org/r/20200710113610.GA92345@mwanda Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-07-03Merge tag 'for-linus-5.8b-rc4-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fixes from Juergen Gross: "One small cleanup patch for ARM and two patches for the xenbus driver fixing latent problems (large stack allocations and bad return code settings)" * tag 'for-linus-5.8b-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/xenbus: let xenbus_map_ring_valloc() return errno values only xen/xenbus: avoid large structs and arrays on the stack arm/xen: remove the unused macro GRANT_TABLE_PHYSADDR
2020-07-02xen/xenbus: let xenbus_map_ring_valloc() return errno values onlyJuergen Gross
Today xenbus_map_ring_valloc() can return either a negative errno value (-ENOMEM or -EINVAL) or a grant status value. This is a mess as e.g -ENOMEM and GNTST_eagain have the same numeric value. Fix that by turning all grant mapping errors into -ENOENT. This is no problem as all callers of xenbus_map_ring_valloc() only use the return value to print an error message, and in case of mapping errors the grant status value has already been printed by __xenbus_map_ring() before. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20200701121638.19840-3-jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-07-02xen/xenbus: avoid large structs and arrays on the stackJuergen Gross
xenbus_map_ring_valloc() and its sub-functions are putting quite large structs and arrays on the stack. This is problematic at runtime, but might also result in build failures (e.g. with clang due to the option -Werror,-Wframe-larger-than=... used). Fix that by moving most of the data from the stack into a dynamically allocated struct. Performance is no issue here, as xenbus_map_ring_valloc() is used only when adding a new PV device to a backend driver. While at it move some duplicated code from pv/hvm specific mapping functions to the single caller. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20200701121638.19840-2-jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-06-12Merge tag 'for-linus-5.8b-rc1-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen updates from Juergen Gross: - several smaller cleanups - a fix for a Xen guest regression with CPU offlining - a small fix in the xen pvcalls backend driver - an update of MAINTAINERS * tag 'for-linus-5.8b-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: MAINTAINERS: Update PARAVIRT_OPS_INTERFACE and VMWARE_HYPERVISOR_INTERFACE xen/pci: Get rid of verbose_request and use dev_dbg() instead xenbus: Use dev_printk() when possible xen-pciback: Use dev_printk() when possible xen: enable BALLOON_MEMORY_HOTPLUG by default xen: expand BALLOON_MEMORY_HOTPLUG description xen/pvcalls: Make pvcalls_back_global static xen/cpuhotplug: Fix initial CPU offlining for PV(H) guests xen-platform: Constify dev_pm_ops xen/pvcalls-back: test for errors when calling backend_connect()
2020-06-09mm: don't include asm/pgtable.h if linux/mm.h is already includedMike Rapoport
Patch series "mm: consolidate definitions of page table accessors", v2. The low level page table accessors (pXY_index(), pXY_offset()) are duplicated across all architectures and sometimes more than once. For instance, we have 31 definition of pgd_offset() for 25 supported architectures. Most of these definitions are actually identical and typically it boils down to, e.g. static inline unsigned long pmd_index(unsigned long address) { return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1); } static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address) { return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address); } These definitions can be shared among 90% of the arches provided XYZ_SHIFT, PTRS_PER_XYZ and xyz_page_vaddr() are defined. For architectures that really need a custom version there is always possibility to override the generic version with the usual ifdefs magic. These patches introduce include/linux/pgtable.h that replaces include/asm-generic/pgtable.h and add the definitions of the page table accessors to the new header. This patch (of 12): The linux/mm.h header includes <asm/pgtable.h> to allow inlining of the functions involving page table manipulations, e.g. pte_alloc() and pmd_alloc(). So, there is no point to explicitly include <asm/pgtable.h> in the files that include <linux/mm.h>. The include statements in such cases are remove with a simple loop: for f in $(git grep -l "include <linux/mm.h>") ; do sed -i -e '/include <asm\/pgtable.h>/ d' $f done Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Cain <bcain@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Ungerer <gerg@linux-m68k.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Mark Salter <msalter@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Mike Rapoport <rppt@kernel.org> Cc: Nick Hu <nickhu@andestech.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20200514170327.31389-1-rppt@kernel.org Link: http://lkml.kernel.org/r/20200514170327.31389-2-rppt@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-27xenbus: Use dev_printk() when possibleBjorn Helgaas
Use dev_printk() when possible to include device and driver information in the conventional format. Add "#define dev_fmt" to preserve KBUILD_MODNAME in messages. No functional change intended. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/20200527174326.254329-3-helgaas@kernel.org Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-04-14xen/xenbus: ensure xenbus_map_ring_valloc() returns proper grant statusJuergen Gross
xenbus_map_ring_valloc() maps a ring page and returns the status of the used grant (0 meaning success). There are Xen hypervisors which might return the value 1 for the status of a failed grant mapping due to a bug. Some callers of xenbus_map_ring_valloc() test for errors by testing the returned status to be less than zero, resulting in no error detected and crashing later due to a not available ring page. Set the return value of xenbus_map_ring_valloc() to GNTST_general_error in case the grant status reported by Xen is greater than zero. This is part of XSA-316. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Wei Liu <wl@xen.org> Link: https://lore.kernel.org/r/20200326080358.1018-1-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2020-04-07xen: Use evtchn_type_t as a type for event channelsYan Yankovskyi
Make event channel functions pass event channel port using evtchn_port_t type. It eliminates signed <-> unsigned conversion. Signed-off-by: Yan Yankovskyi <yyankovskyi@gmail.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20200323152343.GA28422@kbp1-lhp-F74019 Signed-off-by: Juergen Gross <jgross@suse.com>
2020-03-30xen/xenbus: remove unused xenbus_map_ring()Juergen Gross
xenbus_map_ring() is used nowhere in the tree, remove it. xenbus_unmap_ring() is used only locally, so make it static and move it up. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2020-03-05xen/xenbus: fix lockingJuergen Gross
Commit 060eabe8fbe726 ("xenbus/backend: Protect xenbus callback with lock") introduced a bug by holding a lock while calling a function which might schedule. Fix that by using a semaphore instead. Fixes: 060eabe8fbe726 ("xenbus/backend: Protect xenbus callback with lock") Signed-off-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20200305100323.16736-1-jgross@suse.com Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-03-05xenbus: req->err should be updated before req->stateDongli Zhang
This patch adds the barrier to guarantee that req->err is always updated before req->state. Otherwise, read_reply() would not return ERR_PTR(req->err) but req->body, when process_writes()->xb_write() is failed. Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> Link: https://lore.kernel.org/r/20200303221423.21962-2-dongli.zhang@oracle.com Reviewed-by: Julien Grall <jgrall@amazon.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-03-05xenbus: req->body should be updated before req->stateDongli Zhang
The req->body should be updated before req->state is updated and the order should be guaranteed by a barrier. Otherwise, read_reply() might return req->body = NULL. Below is sample callstack when the issue is reproduced on purpose by reordering the updates of req->body and req->state and adding delay in code between updates of req->state and req->body. [ 22.356105] general protection fault: 0000 [#1] SMP PTI [ 22.361185] CPU: 2 PID: 52 Comm: xenwatch Not tainted 5.5.0xen+ #6 [ 22.366727] Hardware name: Xen HVM domU, BIOS ... [ 22.372245] RIP: 0010:_parse_integer_fixup_radix+0x6/0x60 ... ... [ 22.392163] RSP: 0018:ffffb2d64023fdf0 EFLAGS: 00010246 [ 22.395933] RAX: 0000000000000000 RBX: 75746e7562755f6d RCX: 0000000000000000 [ 22.400871] RDX: 0000000000000000 RSI: ffffb2d64023fdfc RDI: 75746e7562755f6d [ 22.405874] RBP: 0000000000000000 R08: 00000000000001e8 R09: 0000000000cdcdcd [ 22.410945] R10: ffffb2d6402ffe00 R11: ffff9d95395eaeb0 R12: ffff9d9535935000 [ 22.417613] R13: ffff9d9526d4a000 R14: ffff9d9526f4f340 R15: ffff9d9537654000 [ 22.423726] FS: 0000000000000000(0000) GS:ffff9d953bc80000(0000) knlGS:0000000000000000 [ 22.429898] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.434342] CR2: 000000c4206a9000 CR3: 00000001ea3fc002 CR4: 00000000001606e0 [ 22.439645] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 22.444941] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 22.450342] Call Trace: [ 22.452509] simple_strtoull+0x27/0x70 [ 22.455572] xenbus_transaction_start+0x31/0x50 [ 22.459104] netback_changed+0x76c/0xcc1 [xen_netfront] [ 22.463279] ? find_watch+0x40/0x40 [ 22.466156] xenwatch_thread+0xb4/0x150 [ 22.469309] ? wait_woken+0x80/0x80 [ 22.472198] kthread+0x10e/0x130 [ 22.474925] ? kthread_park+0x80/0x80 [ 22.477946] ret_from_fork+0x35/0x40 [ 22.480968] Modules linked in: xen_kbdfront xen_fbfront(+) xen_netfront xen_blkfront [ 22.486783] ---[ end trace a9222030a747c3f7 ]--- [ 22.490424] RIP: 0010:_parse_integer_fixup_radix+0x6/0x60 The virt_rmb() is added in the 'true' path of test_reply(). The "while" is changed to "do while" so that test_reply() is used as a read memory barrier. Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> Link: https://lore.kernel.org/r/20200303221423.21962-1-dongli.zhang@oracle.com Reviewed-by: Julien Grall <jgrall@amazon.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-01-29xenbus/backend: Protect xenbus callback with lockSeongJae Park
A driver's 'reclaim_memory' callback can race with 'probe' or 'remove' because it will be called whenever memory pressure is detected. To avoid such race, this commit embeds a spinlock in each 'xenbus_device' and make 'xenbus' to hold the lock while the corresponded callbacks are running. Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: SeongJae Park <sjpark@amazon.de> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2020-01-29xenbus/backend: Add memory pressure handler callbackSeongJae Park
Granting pages consumes backend system memory. In systems configured with insufficient spare memory for those pages, it can cause a memory pressure situation. However, finding the optimal amount of the spare memory is challenging for large systems having dynamic resource utilization patterns. Also, such a static configuration might lack flexibility. To mitigate such problems, this commit adds a memory reclaim callback to 'xenbus_driver'. If a memory pressure is detected, 'xenbus' requests every backend driver to volunarily release its memory. Note that it would be able to improve the callback facility for more sophisticated handlings of general pressures. For example, it would be possible to monitor the memory consumption of each device and issue the release requests to only devices which causing the pressure. Also, the callback could be extended to handle not only memory, but general resources. Nevertheless, this version of the implementation defers such sophisticated goals as a future work. Reviewed-by: Juergen Gross <jgross@suse.com> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> Signed-off-by: SeongJae Park <sjpark@amazon.de> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2019-12-20xenbus: limit when state is forced to closedPaul Durrant
If a driver probe() fails then leave the xenstore state alone. There is no reason to modify it as the failure may be due to transient resource allocation issues and hence a subsequent probe() may succeed. If the driver supports re-binding then only force state to closed during remove() only in the case when the toolstack may need to clean up. This can be detected by checking whether the state in xenstore has been set to closing prior to device removal. NOTE: Re-bind support is indicated by new boolean in struct xenbus_driver, which defaults to false. Subsequent patches will add support to some backend drivers. Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2019-12-20xenbus: move xenbus_dev_shutdown() into frontend code...Paul Durrant
...and make it static xenbus_dev_shutdown() is seemingly intended to cause clean shutdown of PV frontends when a guest is rebooted. Indeed the function waits for a conpletion which is only set by a call to xenbus_frontend_closed(). This patch removes the shutdown() method from backends and moves xenbus_dev_shutdown() from xenbus_probe.c into xenbus_probe_frontend.c, renaming it appropriately and making it static. NOTE: In the case where the backend is running in a driver domain, the toolstack should have already terminated any frontends that may be using it (since Xen does not support re-startable PV driver domains) so xenbus_dev_shutdown() should never be called. Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2019-12-04xen/xenbus: reference count registered modulesPaul Durrant
To prevent a PV driver module being removed whilst attached to its other end, and hence xenbus calling into potentially invalid text, take a reference on the module before calling the probe() method (dropping it if unsuccessful) and drop the reference after returning from the remove() method. Suggested-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2019-10-02xen/xenbus: fix self-deadlock after killing user processJuergen Gross
In case a user process using xenbus has open transactions and is killed e.g. via ctrl-C the following cleanup of the allocated resources might result in a deadlock due to trying to end a transaction in the xenbus worker thread: [ 2551.474706] INFO: task xenbus:37 blocked for more than 120 seconds. [ 2551.492215] Tainted: P OE 5.0.0-29-generic #5 [ 2551.510263] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 2551.528585] xenbus D 0 37 2 0x80000080 [ 2551.528590] Call Trace: [ 2551.528603] __schedule+0x2c0/0x870 [ 2551.528606] ? _cond_resched+0x19/0x40 [ 2551.528632] schedule+0x2c/0x70 [ 2551.528637] xs_talkv+0x1ec/0x2b0 [ 2551.528642] ? wait_woken+0x80/0x80 [ 2551.528645] xs_single+0x53/0x80 [ 2551.528648] xenbus_transaction_end+0x3b/0x70 [ 2551.528651] xenbus_file_free+0x5a/0x160 [ 2551.528654] xenbus_dev_queue_reply+0xc4/0x220 [ 2551.528657] xenbus_thread+0x7de/0x880 [ 2551.528660] ? wait_woken+0x80/0x80 [ 2551.528665] kthread+0x121/0x140 [ 2551.528667] ? xb_read+0x1d0/0x1d0 [ 2551.528670] ? kthread_park+0x90/0x90 [ 2551.528673] ret_from_fork+0x35/0x40 Fix this by doing the cleanup via a workqueue instead. Reported-by: James Dingwall <james@dingwall.me.uk> Fixes: fd8aa9095a95c ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") Cc: <stable@vger.kernel.org> # 4.11 Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2019-05-31Merge tag 'for-linus-5.2b-rc3-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fixes from Juergen Gross: "One minor cleanup patch and a fix for handling of live migration when running as Xen guest" * tag 'for-linus-5.2b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xenbus: Avoid deadlock during suspend due to open transactions xen/pvcalls: Remove set but not used variable
2019-05-28xenbus: Avoid deadlock during suspend due to open transactionsRoss Lagerwall
During a suspend/resume, the xenwatch thread waits for all outstanding xenstore requests and transactions to complete. This does not work correctly for transactions started by userspace because it waits for them to complete after freezing userspace threads which means the transactions have no way of completing, resulting in a deadlock. This is trivial to reproduce by running this script and then suspending the VM: import pyxs, time c = pyxs.client.Client(xen_bus_path="/dev/xen/xenbus") c.connect() c.transaction() time.sleep(3600) Even if this deadlock were resolved, misbehaving userspace should not prevent a VM from being migrated. So, instead of waiting for these transactions to complete before suspending, store the current generation id for each transaction when it is started. The global generation id is incremented during resume. If the caller commits the transaction and the generation id does not match the current generation id, return EAGAIN so that they try again. If the transaction was instead discarded, return OK since no changes were made anyway. This only affects users of the xenbus file interface. In-kernel users of xenbus are assumed to be well-behaved and complete all transactions before freezing. Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2019-05-21treewide: Add SPDX license identifier for more missed filesThomas Gleixner
Add SPDX license identifiers to all files which: - Have no license information of any form - Have MODULE_LICENCE("GPL*") inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-25xenbus: drop useless LIST_HEAD in xenbus_write_watch() and xenbus_file_write()Mao Wenan
Drop LIST_HEAD where the variable it declares is never used. The declarations were introduced with the file, but the declared variables were not used. Fixes: 1107ba885e469 ("xen: add xenfs to allow usermode <-> Xen interaction") Signed-off-by: Mao Wenan <maowenan@huawei.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2019-04-06fs: stream_open - opener for stream-like files so that read and write can ↵Kirill Smelkov
run simultaneously without deadlock Commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per POSIX") added locking for file.f_pos access and in particular made concurrent read and write not possible - now both those functions take f_pos lock for the whole run, and so if e.g. a read is blocked waiting for data, write will deadlock waiting for that read to complete. This caused regression for stream-like files where previously read and write could run simultaneously, but after that patch could not do so anymore. See e.g. commit 581d21a2d02a ("xenbus: fix deadlock on writes to /proc/xen/xenbus") which fixes such regression for particular case of /proc/xen/xenbus. The patch that added f_pos lock in 2014 did so to guarantee POSIX thread safety for read/write/lseek and added the locking to file descriptors of all regular files. In 2014 that thread-safety problem was not new as it was already discussed earlier in 2006. However even though 2006'th version of Linus's patch was adding f_pos locking "only for files that are marked seekable with FMODE_LSEEK (thus avoiding the stream-like objects like pipes and sockets)", the 2014 version - the one that actually made it into the tree as 9c225f2655e3 - is doing so irregardless of whether a file is seekable or not. See https://lore.kernel.org/lkml/53022DB1.4070805@gmail.com/ https://lwn.net/Articles/180387 https://lwn.net/Articles/180396 for historic context. The reason that it did so is, probably, that there are many files that are marked non-seekable, but e.g. their read implementation actually depends on knowing current position to correctly handle the read. Some examples: kernel/power/user.c snapshot_read fs/debugfs/file.c u32_array_read fs/fuse/control.c fuse_conn_waiting_read + ... drivers/hwmon/asus_atk0110.c atk_debugfs_ggrp_read arch/s390/hypfs/inode.c hypfs_read_iter ... Despite that, many nonseekable_open users implement read and write with pure stream semantics - they don't depend on passed ppos at all. And for those cases where read could wait for something inside, it creates a situation similar to xenbus - the write could be never made to go until read is done, and read is waiting for some, potentially external, event, for potentially unbounded time -> deadlock. Besides xenbus, there are 14 such places in the kernel that I've found with semantic patch (see below): drivers/xen/evtchn.c:667:8-24: ERROR: evtchn_fops: .read() can deadlock .write() drivers/isdn/capi/capi.c:963:8-24: ERROR: capi_fops: .read() can deadlock .write() drivers/input/evdev.c:527:1-17: ERROR: evdev_fops: .read() can deadlock .write() drivers/char/pcmcia/cm4000_cs.c:1685:7-23: ERROR: cm4000_fops: .read() can deadlock .write() net/rfkill/core.c:1146:8-24: ERROR: rfkill_fops: .read() can deadlock .write() drivers/s390/char/fs3270.c:488:1-17: ERROR: fs3270_fops: .read() can deadlock .write() drivers/usb/misc/ldusb.c:310:1-17: ERROR: ld_usb_fops: .read() can deadlock .write() drivers/hid/uhid.c:635:1-17: ERROR: uhid_fops: .read() can deadlock .write() net/batman-adv/icmp_socket.c:80:1-17: ERROR: batadv_fops: .read() can deadlock .write() drivers/media/rc/lirc_dev.c:198:1-17: ERROR: lirc_fops: .read() can deadlock .write() drivers/leds/uleds.c:77:1-17: ERROR: uleds_fops: .read() can deadlock .write() drivers/input/misc/uinput.c:400:1-17: ERROR: uinput_fops: .read() can deadlock .write() drivers/infiniband/core/user_mad.c:985:7-23: ERROR: umad_fops: .read() can deadlock .write() drivers/gnss/core.c:45:1-17: ERROR: gnss_fops: .read() can deadlock .write() In addition to the cases above another regression caused by f_pos locking is that now FUSE filesystems that implement open with FOPEN_NONSEEKABLE flag, can no longer implement bidirectional stream-like files - for the same reason as above e.g. read can deadlock write locking on file.f_pos in the kernel. FUSE's FOPEN_NONSEEKABLE was added in 2008 in a7c1b990f715 ("fuse: implement nonseekable open") to support OSSPD. OSSPD implements /dev/dsp in userspace with FOPEN_NONSEEKABLE flag, with corresponding read and write routines not depending on current position at all, and with both read and write being potentially blocking operations: See https://github.com/libfuse/osspd https://lwn.net/Articles/308445 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1406 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1438-L1477 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1479-L1510 Corresponding libfuse example/test also describes FOPEN_NONSEEKABLE as "somewhat pipe-like files ..." with read handler not using offset. However that test implements only read without write and cannot exercise the deadlock scenario: https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L124-L131 https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L146-L163 https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L209-L216 I've actually hit the read vs write deadlock for real while implementing my FUSE filesystem where there is /head/watch file, for which open creates separate bidirectional socket-like stream in between filesystem and its user with both read and write being later performed simultaneously. And there it is semantically not easy to split the stream into two separate read-only and write-only channels: https://lab.nexedi.com/kirr/wendelin.core/blob/f13aa600/wcfs/wcfs.go#L88-169 Let's fix this regression. The plan is: 1. We can't change nonseekable_open to include &~FMODE_ATOMIC_POS - doing so would break many in-kernel nonseekable_open users which actually use ppos in read/write handlers. 2. Add stream_open() to kernel to open stream-like non-seekable file descriptors. Read and write on such file descriptors would never use nor change ppos. And with that property on stream-like files read and write will be running without taking f_pos lock - i.e. read and write could be running simultaneously. 3. With semantic patch search and convert to stream_open all in-kernel nonseekable_open users for which read and write actually do not depend on ppos and where there is no other methods in file_operations which assume @offset access. 4. Add FOPEN_STREAM to fs/fuse/ and open in-kernel file-descriptors via steam_open if that bit is present in filesystem open reply. It was tempting to change fs/fuse/ open handler to use stream_open instead of nonseekable_open on just FOPEN_NONSEEKABLE flags, but grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE, and in particular GVFS which actually uses offset in its read and write handlers https://codesearch.debian.net/search?q=-%3Enonseekable+%3D https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481 so if we would do such a change it will break a real user. 5. Add stream_open and FOPEN_STREAM handling to stable kernels starting from v3.14+ (the kernel where 9c225f2655 first appeared). This will allow to patch OSSPD and other FUSE filesystems that provide stream-like files to return FOPEN_STREAM | FOPEN_NONSEEKABLE in their open handler and this way avoid the deadlock on all kernel versions. This should work because fs/fuse/ ignores unknown open flags returned from a filesystem and so passing FOPEN_STREAM to a kernel that is not aware of this flag cannot hurt. In turn the kernel that is not aware of FOPEN_STREAM will be < v3.14 where just FOPEN_NONSEEKABLE is sufficient to implement streams without read vs write deadlock. This patch adds stream_open, converts /proc/xen/xenbus to it and adds semantic patch to automatically locate in-kernel places that are either required to be converted due to read vs write deadlock, or that are just safe to be converted because read and write do not use ppos and there are no other funky methods in file_operations. Regarding semantic patch I've verified each generated change manually - that it is correct to convert - and each other nonseekable_open instance left - that it is either not correct to convert there, or that it is not converted due to current stream_open.cocci limitations. The script also does not convert files that should be valid to convert, but that currently have .llseek = noop_llseek or generic_file_llseek for unknown reason despite file being opened with nonseekable_open (e.g. drivers/input/mousedev.c) Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Yongzhi Pan <panyongzhi@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Tejun Heo <tj@kernel.org> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Julia Lawall <Julia.Lawall@lip6.fr> Cc: Nikolaus Rath <Nikolaus@rath.org> Cc: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Kirill Smelkov <kirr@nexedi.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26xen: drop writing error messages to xenstoreJuergen Gross
xenbus_va_dev_error() will try to write error messages to Xenstore under the error/<dev-name>/error node (with <dev-name> something like "device/vbd/51872"). This will fail normally and another message about this failure is added to dmesg. I believe this is a remnant from very ancient times, as it was added in the first pvops rush of commits in 2007. So remove the additional message when writing to Xenstore failed as a minimum step. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracel.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2018-08-28xen: export device state to sysfsJoe Jin
Export device state to sysfs to allow for easier get device state. Signed-off-by: Joe Jin <joe.jin@oracle.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-05-17xen/store: do not store local values in xen_start_infoRoger Pau Monne
There's no need to store the xenstore page or event channel in xen_start_info if they are locally initialized. This also fixes PVH local xenstore initialization due to the lack of xen_start_info in that case. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2018-04-17xen: xenbus_dev_frontend: Really return response stringSimon Gaiser
xenbus_command_reply() did not actually copy the response string and leaked stack content instead. Fixes: 9a6161fe73bd ("xen: return xenstore command failures via response instead of rc") Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-03-21xen: xenbus_dev_frontend: Verify body of XS_TRANSACTION_ENDSimon Gaiser
By guaranteeing that the argument of XS_TRANSACTION_END is valid we can assume that the transaction has been closed when we get an XS_ERROR response from xenstore (Note that we already verify that it's a valid transaction id). Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-03-21xen: xenbus: Catch closing of non existent transactionsSimon Gaiser
Users of the xenbus functions should never close a non existent transaction (for example by trying to closing the same transaction twice) but better catch it in xs_request_exit() than to corrupt the reference counter. Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-03-21xen: xenbus_dev_frontend: Fix XS_TRANSACTION_END handlingSimon Gaiser
Commit fd8aa9095a95 ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") made a subtle change to the semantic of xenbus_dev_request_and_reply() and xenbus_transaction_end(). Before on an error response to XS_TRANSACTION_END xenbus_dev_request_and_reply() would not decrement the active transaction counter. But xenbus_transaction_end() has always counted the transaction as finished regardless of the response. The new behavior is that xenbus_dev_request_and_reply() and xenbus_transaction_end() will always count the transaction as finished regardless the response code (handled in xs_request_exit()). But xenbus_dev_frontend tries to end a transaction on closing of the device if the XS_TRANSACTION_END failed before. Trying to close the transaction twice corrupts the reference count. So fix this by also considering a transaction closed if we have sent XS_TRANSACTION_END once regardless of the return code. Cc: <stable@vger.kernel.org> # 4.11 Fixes: fd8aa9095a95 ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-03-08xen: xenbus: use put_device() instead of kfree()Arvind Yadav
Never directly free @dev after calling device_register(), even if it returned an error! Always use put_device() to give up the reference initialized. Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2018-02-17xenbus: track caller request idJoao Martins
Commit fd8aa9095a95 ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") optimized xenbus concurrent accesses but in doing so broke UABI of /dev/xen/xenbus. Through /dev/xen/xenbus applications are in charge of xenbus message exchange with the correct header and body. Now, after the mentioned commit the replies received by application will no longer have the header req_id echoed back as it was on request (see specification below for reference), because that particular field is being overwritten by kernel. struct xsd_sockmsg { uint32_t type; /* XS_??? */ uint32_t req_id;/* Request identifier, echoed in daemon's response. */ uint32_t tx_id; /* Transaction id (0 if not related to a transaction). */ uint32_t len; /* Length of data following this. */ /* Generally followed by nul-terminated string(s). */ }; Before there was only one request at a time so req_id could simply be forwarded back and forth. To allow simultaneous requests we need a different req_id for each message thus kernel keeps a monotonic increasing counter for this field and is written on every request irrespective of userspace value. Forwarding again the req_id on userspace requests is not a solution because we would open the possibility of userspace-generated req_id colliding with kernel ones. So this patch instead takes another route which is to artificially keep user req_id while keeping the xenbus logic as is. We do that by saving the original req_id before xs_send(), use the private kernel counter as req_id and then once reply comes and was validated, we restore back the original req_id. Cc: <stable@vger.kernel.org> # 4.11 Fixes: fd8aa9095a ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") Reported-by: Bhavesh Davda <bhavesh.davda@oracle.com> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2018-02-11vfs: do bulk POLL* -> EPOLL* replacementLinus Torvalds
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-28the rest of drivers/*: annotate ->poll() instancesAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-11-16Merge tag 'for-linus-4.15-rc1-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen updates from Juergen Gross: "Xen features and fixes for v4.15-rc1 Apart from several small fixes it contains the following features: - a series by Joao Martins to add vdso support of the pv clock interface - a series by Juergen Gross to add support for Xen pv guests to be able to run on 5 level paging hosts - a series by Stefano Stabellini adding the Xen pvcalls frontend driver using a paravirtualized socket interface" * tag 'for-linus-4.15-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: (34 commits) xen/pvcalls: fix potential endless loop in pvcalls-front.c xen/pvcalls: Add MODULE_LICENSE() MAINTAINERS: xen, kvm: track pvclock-abi.h changes x86/xen/time: setup vcpu 0 time info page x86/xen/time: set pvclock flags on xen_time_init() x86/pvclock: add setter for pvclock_pvti_cpu0_va ptp_kvm: probe for kvm guest availability xen/privcmd: remove unused variable pageidx xen: select grant interface version xen: update arch/x86/include/asm/xen/cpuid.h xen: add grant interface version dependent constants to gnttab_ops xen: limit grant v2 interface to the v1 functionality xen: re-introduce support for grant v2 interface xen: support priv-mapping in an HVM tools domain xen/pvcalls: remove redundant check for irq >= 0 xen/pvcalls: fix unsigned less than zero error check xen/time: Return -ENODEV from xen_get_wallclock() xen/pvcalls-front: mark expected switch fall-through xen: xenbus_probe_frontend: mark expected switch fall-throughs xen/time: do not decrease steal time after live migration on xen ...
2017-11-03xen: xenbus_probe_frontend: mark expected switch fall-throughsGustavo A. R. Silva
In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. Addresses-Coverity-ID: 146562 Addresses-Coverity-ID: 146563 Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-18xen: don't compile pv-specific parts if XEN_PV isn't configuredJuergen Gross
xenbus_client.c contains some functions specific for pv guests. Enclose them with #ifdef CONFIG_XEN_PV to avoid compiling them when they are not needed (e.g. on ARM). Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-08-11xen: avoid deadlock in xenbusJuergen Gross
When starting the xenwatch thread a theoretical deadlock situation is possible: xs_init() contains: task = kthread_run(xenwatch_thread, NULL, "xenwatch"); if (IS_ERR(task)) return PTR_ERR(task); xenwatch_pid = task->pid; And xenwatch_thread() does: mutex_lock(&xenwatch_mutex); ... event->handle->callback(); ... mutex_unlock(&xenwatch_mutex); The callback could call unregister_xenbus_watch() which does: ... if (current->pid != xenwatch_pid) mutex_lock(&xenwatch_mutex); ... In case a watch is firing before xenwatch_pid could be set and the callback of that watch unregisters a watch, then a self-deadlock would occur. Avoid this by setting xenwatch_pid in xenwatch_thread(). Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2017-06-25xen: avoid deadlock in xenbus driverJuergen Gross
There has been a report about a deadlock in the xenbus driver: [ 247.979498] ====================================================== [ 247.985688] WARNING: possible circular locking dependency detected [ 247.991882] 4.12.0-rc4-00022-gc4b25c0 #575 Not tainted [ 247.997040] ------------------------------------------------------ [ 248.003232] xenbus/91 is trying to acquire lock: [ 248.007875] (&u->msgbuffer_mutex){+.+.+.}, at: [<ffff00000863e904>] xenbus_dev_queue_reply+0x3c/0x230 [ 248.017163] [ 248.017163] but task is already holding lock: [ 248.023096] (xb_write_mutex){+.+...}, at: [<ffff00000863a940>] xenbus_thread+0x5f0/0x798 [ 248.031267] [ 248.031267] which lock already depends on the new lock. [ 248.031267] [ 248.039615] [ 248.039615] the existing dependency chain (in reverse order) is: [ 248.047176] [ 248.047176] -> #1 (xb_write_mutex){+.+...}: [ 248.052943] __lock_acquire+0x1728/0x1778 [ 248.057498] lock_acquire+0xc4/0x288 [ 248.061630] __mutex_lock+0x84/0x868 [ 248.065755] mutex_lock_nested+0x3c/0x50 [ 248.070227] xs_send+0x164/0x1f8 [ 248.074015] xenbus_dev_request_and_reply+0x6c/0x88 [ 248.079427] xenbus_file_write+0x260/0x420 [ 248.084073] __vfs_write+0x48/0x138 [ 248.088113] vfs_write+0xa8/0x1b8 [ 248.091983] SyS_write+0x54/0xb0 [ 248.095768] el0_svc_naked+0x24/0x28 [ 248.099897] [ 248.099897] -> #0 (&u->msgbuffer_mutex){+.+.+.}: [ 248.106088] print_circular_bug+0x80/0x2e0 [ 248.110730] __lock_acquire+0x1768/0x1778 [ 248.115288] lock_acquire+0xc4/0x288 [ 248.119417] __mutex_lock+0x84/0x868 [ 248.123545] mutex_lock_nested+0x3c/0x50 [ 248.128016] xenbus_dev_queue_reply+0x3c/0x230 [ 248.133005] xenbus_thread+0x788/0x798 [ 248.137306] kthread+0x110/0x140 [ 248.141087] ret_from_fork+0x10/0x40 It is rather easy to avoid by dropping xb_write_mutex before calling xenbus_dev_queue_reply(). Fixes: fd8aa9095a95c02dcc35540a263267c29b8fda9d ("xen: optimize xenbus driver for multiple concurrent xenstore accesses"). Cc: <stable@vger.kernel.org> # 4.11 Reported-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Juergen Gross <jgross@suse.com> Tested-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2017-04-04xenbus: remove transaction holder from list before freeingJan Beulich
After allocation the item is being placed on the list right away. Consequently it needs to be taken off the list before freeing in the case xenbus_dev_request_and_reply() failed, as in that case the callback (xenbus_dev_queue_reply()) is not being called (and if it was called, it should do both). Fixes: 5584ea250ae44f929feb4c7bd3877d1c5edbf813 Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-02-27xenbus: Remove duplicate inclusion of linux/init.hMasanari Iida
This patch remove duplicate inclusion of linux/init.h in xenbus_dev_frontend.c. Confirm successfully compile after remove the line. Signed-off-by: Masanari Iida <standby24x7@gmail.com> Reviewed-by: Juergen Gross <jgross@suse.com>
2017-02-09xen: optimize xenbus driver for multiple concurrent xenstore accessesJuergen Gross
Handling of multiple concurrent Xenstore accesses through xenbus driver either from the kernel or user land is rather lame today: xenbus is capable to have one access active only at one point of time. Rewrite xenbus to handle multiple requests concurrently by making use of the request id of the Xenstore protocol. This requires to: - Instead of blocking inside xb_read() when trying to read data from the xenstore ring buffer do so only in the main loop of xenbus_thread(). - Instead of doing writes to the xenstore ring buffer in the context of the caller just queue the request and do the write in the dedicated xenbus thread. - Instead of just forwarding the request id specified by the caller of xenbus to xenstore use a xenbus internal unique request id. This will allow multiple outstanding requests. - Modify the locking scheme in order to allow multiple requests being active in parallel. - Instead of waiting for the reply of a user's xenstore request after writing the request to the xenstore ring buffer return directly to the caller and do the waiting in the read path. Additionally signal handling was optimized by avoiding waking up the xenbus thread or sending an event to Xenstore in case the addressed entity is known to be running already. As a result communication with Xenstore is sped up by a factor of up to 5: depending on the request type (read or write) and the amount of data transferred the gain was at least 20% (small reads) and went up to a factor of 5 for large writes. In the end some more rough edges of xenbus have been smoothed: - Handling of memory shortage when reading from xenstore ring buffer in the xenbus driver was not optimal: it was busy looping and issuing a warning in each loop. - In case of xenstore not running in dom0 but in a stubdom we end up with two xenbus threads running as the initialization of xenbus in dom0 expecting a local xenstored will be redone later when connecting to the xenstore domain. Up to now this was no problem as locking would prevent the two xenbus threads interfering with each other, but this was just a waste of kernel resources. - An out of memory situation while writing to or reading from the xenstore ring buffer no longer will lead to a possible loss of synchronization with xenstore. - The user read and write part are now interruptible by signals. Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-02-09xen: modify xenstore watch event interfaceJuergen Gross
Today a Xenstore watch event is delivered via a callback function declared as: void (*callback)(struct xenbus_watch *, const char **vec, unsigned int len); As all watch events only ever come with two parameters (path and token) changing the prototype to: void (*callback)(struct xenbus_watch *, const char *path, const char *token); is the natural thing to do. Apply this change and adapt all users. Cc: konrad.wilk@oracle.com Cc: roger.pau@citrix.com Cc: wei.liu2@citrix.com Cc: paul.durrant@citrix.com Cc: netdev@vger.kernel.org Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Paul Durrant <paul.durrant@citrix.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-02-09xen: clean up xenbus internal headersJuergen Gross
The xenbus driver has an awful mixture of internally and globally visible headers: some of the internally used only stuff is defined in the global header include/xen/xenbus.h while some stuff defined in internal headers is used by other drivers, too. Clean this up by moving the externally used symbols to include/xen/xenbus.h and the symbols used internally only to a new header drivers/xen/xenbus/xenbus.h replacing xenbus_comms.h and xenbus_probe.h Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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