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path: root/drivers/usb/core/notify.c
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2019-06-26USB: core: Remove usbfs_mutexAlan Stern
Commit 4a2a8a2cce86 ("usbfs: private mutex for open, release, and remove") is now obsolete. The commit was created back when we had to handle both usbfs device nodes and the old usbdevfs filesystem (/proc/bus/usb/), but usbdevfs no longer exists. This means there's no longer any need to hold a mutex during two separate removal operations (and thus during an entire notifier chain call). Furthermore, the one remaining remove/release pair doesn't race with open thanks to the synchronization provided by the device model core in bus_find_device(). Remove and release don't race with each other because they both run with the device lock held. The upshot is that usbfs_mutex isn't needed any more. This patch removes it entirely. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03USB: core: move existing SPDX tags to top of the fileGreg Kroah-Hartman
To match the rest of the kernel, the SPDX tags for the drivers/usb/core/ files are moved to the first line of the file. This makes it more obvious the tag is present as well as making it match the other 12k files in the tree with this location. It also uses // to match the "expected style" as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-10-29USB: core: add missing license information to some filesGreg Kroah-Hartman
Some of the USB core files were missing explicit license information. As all files in the kernel tree are implicitly licensed under the GPLv2-only, be explicit in case someone get confused looking at individual files by using the SPDX nomenclature. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2011-10-31usb: Add export.h for EXPORT_SYMBOL/THIS_MODULE where neededPaul Gortmaker
With module.h being implicitly everywhere via device.h, the absence of explicitly including something for EXPORT_SYMBOL went unnoticed. Since we are heading to fix things up and clean module.h from the device.h file, we need to explicitly include these files now. Use the lightweight version of the header that has just THIS_MODULE and EXPORT_SYMBOL variants. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2008-02-01USB : correct comments in usb/core/notify.cManish Katiyar
This patch corrects the wrong function name mentioned in the comments of usb_unregister_notify function. Signed-off-by: Manish Katiyar <mkatiyar@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-09-27usbfs: private mutex for open, release, and removeAlan Stern
The usbfs code doesn't provide sufficient mutual exclusion among open, release, and remove. Release vs. remove is okay because they both acquire the device lock, but open is not exclusive with either one. All three routines modify the udev->filelist linked list, so they must not run concurrently. Apparently someone gave this a minimum amount of thought in the past by explicitly acquiring the BKL at the start of the usbdev_open routine. Oddly enough, there's a comment pointing out that locking is unnecessary because chrdev_open already has acquired the BKL. But this ignores the point that the files in /proc/bus/usb/* are not char device files; they are regular files and so they don't get any special locking. Furthermore it's necessary to acquire the same lock in the release and remove routines, which the code does not do. Yet another problem arises because the same file_operations structure is accessible through both the /proc/bus/usb/* and /dev/usb/usbdev* file nodes. Even when one of them has been removed, it's still possible for userspace to open the other. So simple locking around the individual remove routines is insufficient; we need to lock the entire usb_notify_remove_device notifier chain. Rather than rely on the BKL, this patch (as723) introduces a new private mutex for the purpose. Holding the BKL while invoking a notifier chain doesn't seem like a good idea. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-06-30Remove obsolete #include <linux/config.h>Jörn Engel
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-03-27[PATCH] Notifier chain update: API changesAlan Stern
The kernel's implementation of notifier chains is unsafe. There is no protection against entries being added to or removed from a chain while the chain is in use. The issues were discussed in this thread: http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2 We noticed that notifier chains in the kernel fall into two basic usage classes: "Blocking" chains are always called from a process context and the callout routines are allowed to sleep; "Atomic" chains can be called from an atomic context and the callout routines are not allowed to sleep. We decided to codify this distinction and make it part of the API. Therefore this set of patches introduces three new, parallel APIs: one for blocking notifiers, one for atomic notifiers, and one for "raw" notifiers (which is really just the old API under a new name). New kinds of data structures are used for the heads of the chains, and new routines are defined for registration, unregistration, and calling a chain. The three APIs are explained in include/linux/notifier.h and their implementation is in kernel/sys.c. With atomic and blocking chains, the implementation guarantees that the chain links will not be corrupted and that chain callers will not get messed up by entries being added or removed. For raw chains the implementation provides no guarantees at all; users of this API must provide their own protections. (The idea was that situations may come up where the assumptions of the atomic and blocking APIs are not appropriate, so it should be possible for users to handle these things in their own way.) There are some limitations, which should not be too hard to live with. For atomic/blocking chains, registration and unregistration must always be done in a process context since the chain is protected by a mutex/rwsem. Also, a callout routine for a non-raw chain must not try to register or unregister entries on its own chain. (This did happen in a couple of places and the code had to be changed to avoid it.) Since atomic chains may be called from within an NMI handler, they cannot use spinlocks for synchronization. Instead we use RCU. The overhead falls almost entirely in the unregister routine, which is okay since unregistration is much less frequent that calling a chain. Here is the list of chains that we adjusted and their classifications. None of them use the raw API, so for the moment it is only a placeholder. ATOMIC CHAINS ------------- arch/i386/kernel/traps.c: i386die_chain arch/ia64/kernel/traps.c: ia64die_chain arch/powerpc/kernel/traps.c: powerpc_die_chain arch/sparc64/kernel/traps.c: sparc64die_chain arch/x86_64/kernel/traps.c: die_chain drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list kernel/panic.c: panic_notifier_list kernel/profile.c: task_free_notifier net/bluetooth/hci_core.c: hci_notifier net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain net/ipv6/addrconf.c: inet6addr_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain net/netlink/af_netlink.c: netlink_chain BLOCKING CHAINS --------------- arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain arch/s390/kernel/process.c: idle_chain arch/x86_64/kernel/process.c idle_notifier drivers/base/memory.c: memory_chain drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list drivers/macintosh/adb.c: adb_client_list drivers/macintosh/via-pmu.c sleep_notifier_list drivers/macintosh/via-pmu68k.c sleep_notifier_list drivers/macintosh/windfarm_core.c wf_client_list drivers/usb/core/notify.c usb_notifier_list drivers/video/fbmem.c fb_notifier_list kernel/cpu.c cpu_chain kernel/module.c module_notify_list kernel/profile.c munmap_notifier kernel/profile.c task_exit_notifier kernel/sys.c reboot_notifier_list net/core/dev.c netdev_chain net/decnet/dn_dev.c: dnaddr_chain net/ipv4/devinet.c: inetaddr_chain It's possible that some of these classifications are wrong. If they are, please let us know or submit a patch to fix them. Note that any chain that gets called very frequently should be atomic, because the rwsem read-locking used for blocking chains is very likely to incur cache misses on SMP systems. (However, if the chain's callout routines may sleep then the chain cannot be atomic.) The patch set was written by Alan Stern and Chandra Seetharaman, incorporating material written by Keith Owens and suggestions from Paul McKenney and Andrew Morton. [jes@sgi.com: restructure the notifier chain initialization macros] Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-20[PATCH] USB: convert a bunch of USB semaphores to mutexesArjan van de Ven
the patch below converts a bunch of semaphores-used-as-mutex in the USB code to mutexes Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-11-17[PATCH] USB: move CONFIG_USB_DEBUG checks into the MakefileGreg Kroah-Hartman
This lets us remove a lot of code in the drivers that were all checking the same thing. It also found some bugs in a few of the drivers, which has been fixed up. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-28[PATCH] USB: add notifier functions to the USB core for devices and bussesGreg Kroah-Hartman
This should let us get rid of all of the different hooks in the USB core for when something has changed. Also, some other parts of the kernel have wanted to know this kind of information at times. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>