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2014-05-20sysfs: make sure read buffer is zeroedTejun Heo
13c589d5b0ac ("sysfs: use seq_file when reading regular files") switched sysfs from custom read implementation to seq_file to enable later transition to kernfs. After the change, the buffer passed to ->show() is acquired through seq_get_buf(); unfortunately, this introduces a subtle behavior change. Before the commit, the buffer passed to ->show() was always zero as it was allocated using get_zeroed_page(). Because seq_file doesn't clear buffers on allocation and neither does seq_get_buf(), after the commit, depending on the behavior of ->show(), we may end up exposing uninitialized data to userland thus possibly altering userland visible behavior and leaking information. Fix it by explicitly clearing the buffer. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Ron <ron@debian.org> Fixes: 13c589d5b0ac ("sysfs: use seq_file when reading regular files") Cc: stable <stable@vger.kernel.org> # 3.13+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-16sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo
All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-25Revert "sysfs, driver-core: remove unused ↵Greg Kroah-Hartman
{sysfs|device}_schedule_callback_owner()" This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888. As reported by Stephen, this patch breaks linux-next as a ppc patch suddenly (after 2 years) started using this old api call. So revert it for now, it will go away in 3.15-rc2 when we can change the PPC call to the new api. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Tejun Heo <tj@kernel.org> Cc: Stewart Smith <stewart@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo
All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-07kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappersTejun Heo
Sometimes it's necessary to implement a node which wants to delete nodes including itself. This isn't straightforward because of kernfs active reference. While a file operation is in progress, an active reference is held and kernfs_remove() waits for all such references to drain before completing. For a self-deleting node, this is a deadlock as kernfs_remove() ends up waiting for an active reference that itself is sitting on top of. This currently is worked around in the sysfs layer using sysfs_schedule_callback() which makes such removals asynchronous. While it works, it's rather cumbersome and inherently breaks synchronicity of the operation - the file operation which triggered the operation may complete before the removal is finished (or even started) and the removal may fail asynchronously. If a removal operation is immmediately followed by another operation which expects the specific name to be available (e.g. removal followed by rename onto the same name), there's no way to make the latter operation reliable. The thing is there's no inherent reason for this to be asynchrnous. All that's necessary to do this synchronous is a dedicated operation which drops its own active ref and deactivates self. This patch implements kernfs_remove_self() and its wrappers in sysfs and driver core. kernfs_remove_self() is to be called from one of the file operations, drops the active ref the task is holding, removes the self node, and restores active ref to the dead node so that the ref is balanced afterwards. __kernfs_remove() is updated so that it takes an early exit if the target node is already fully removed so that the active ref restored by kernfs_remove_self() after removal doesn't confuse the deactivation path. This makes implementing self-deleting nodes very easy. The normal removal path doesn't even need to be changed to use kernfs_remove_self() for the self-deleting node. The method can invoke kernfs_remove_self() on itself before proceeding the normal removal path. kernfs_remove() invoked on the node by the normal deletion path will simply be ignored. This will replace sysfs_schedule_callback(). A subtle feature of sysfs_schedule_callback() is that it collapses multiple invocations - even if multiple removals are triggered, the removal callback is run only once. An equivalent effect can be achieved by testing the return value of kernfs_remove_self() - only the one which gets %true return value should proceed with actual deletion. All other instances of kernfs_remove_self() will wait till the enclosing kernfs operation which invoked the winning instance of kernfs_remove_self() finishes and then return %false. This trivially makes all users of kernfs_remove_self() automatically show correct synchronous behavior even when there are multiple concurrent operations - all "echo 1 > delete" instances will finish only after the whole operation is completed by one of the instances. Note that manipulation of active ref is implemented in separate public functions - kernfs_[un]break_active_protection(). kernfs_remove_self() is the only user at the moment but this will be used to cater to more complex cases. v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing and sysfs_remove_file_self() had incorrect return type. Fix it. Reported by kbuild test bot. v3: kernfs_[un]break_active_protection() separated out from kernfs_remove_self() and exposed as public API. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-13Revert "kernfs, sysfs, driver-core: implement kernfs_remove_self() and its ↵Greg Kroah-Hartman
wrappers" This reverts commit 1ae06819c77cff1ea2833c94f8c093fe8a5c79db. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-13Revert "sysfs, driver-core: remove unused ↵Greg Kroah-Hartman
{sysfs|device}_schedule_callback_owner()" This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888. Tejun writes: I'm sorry but can you please revert the whole series? get_active() waiting while a node is deactivated has potential to lead to deadlock and that deactivate/reactivate interface is something fundamentally flawed and that cgroup will have to work with the remove_self() like everybody else. IOW, I think the first posting was correct. Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-10sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()Tejun Heo
All device_schedule_callback_owner() users are converted to use device_remove_file_self(). Remove now unused {sysfs|device}_schedule_callback_owner(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-10kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappersTejun Heo
Sometimes it's necessary to implement a node which wants to delete nodes including itself. This isn't straightforward because of kernfs active reference. While a file operation is in progress, an active reference is held and kernfs_remove() waits for all such references to drain before completing. For a self-deleting node, this is a deadlock as kernfs_remove() ends up waiting for an active reference that itself is sitting on top of. This currently is worked around in the sysfs layer using sysfs_schedule_callback() which makes such removals asynchronous. While it works, it's rather cumbersome and inherently breaks synchronicity of the operation - the file operation which triggered the operation may complete before the removal is finished (or even started) and the removal may fail asynchronously. If a removal operation is immmediately followed by another operation which expects the specific name to be available (e.g. removal followed by rename onto the same name), there's no way to make the latter operation reliable. The thing is there's no inherent reason for this to be asynchrnous. All that's necessary to do this synchronous is a dedicated operation which drops its own active ref and deactivates self. This patch implements kernfs_remove_self() and its wrappers in sysfs and driver core. kernfs_remove_self() is to be called from one of the file operations, drops the active ref and deactivates using __kernfs_deactivate_self(), removes the self node, and restores active ref to the dead node using __kernfs_reactivate_self() so that the ref is balanced afterwards. __kernfs_remove() is updated so that it takes an early exit if the target node is already fully removed so that the active ref restored by kernfs_remove_self() after removal doesn't confuse the deactivation path. This makes implementing self-deleting nodes very easy. The normal removal path doesn't even need to be changed to use kernfs_remove_self() for the self-deleting node. The method can invoke kernfs_remove_self() on itself before proceeding the normal removal path. kernfs_remove() invoked on the node by the normal deletion path will simply be ignored. This will replace sysfs_schedule_callback(). A subtle feature of sysfs_schedule_callback() is that it collapses multiple invocations - even if multiple removals are triggered, the removal callback is run only once. An equivalent effect can be achieved by testing the return value of kernfs_remove_self() - only the one which gets %true return value should proceed with actual deletion. All other instances of kernfs_remove_self() will wait till the enclosing kernfs operation which invoked the winning instance of kernfs_remove_self() finishes and then return %false. This trivially makes all users of kernfs_remove_self() automatically show correct synchronous behavior even when there are multiple concurrent operations - all "echo 1 > delete" instances will finish only after the whole operation is completed by one of the instances. v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing and sysfs_remove_file_self() had incorrect return type. Fix it. Reported by kbuild test bot. v3: Updated to use __kernfs_{de|re}activate_self(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-17kernfs: mark static names with KERNFS_STATIC_NAMETejun Heo
Because sysfs used struct attribute which are supposed to stay constant, sysfs didn't copy names when creating regular files. The specified string for name was supposed to stay constant. Such distinction isn't inherent for kernfs. kernfs_create_file[_ns]() should be able to take the same @name as kernfs_create_dir[_ns]() As there can be huge number of sysfs attributes, we still want to be able to use static names for sysfs attributes. This patch renames kernfs_create_file_ns_key() to __kernfs_create_file() and adds @name_is_static parameter so that the caller can explicitly indicate that @name can be used without copying. kernfs is updated to use KERNFS_STATIC_NAME to distinguish static and copied names. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-11kernfs: s/sysfs/kernfs/ in constantsTejun Heo
kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. This patch performs the following renames. * s/SYSFS_DIR/KERNFS_DIR/ * s/SYSFS_KOBJ_ATTR/KERNFS_FILE/ * s/SYSFS_KOBJ_LINK/KERNFS_LINK/ * s/SYSFS_{TYPE_FLAGS}/KERNFS_{TYPE_FLAGS}/ * s/SYSFS_FLAG_{FLAG}/KERNFS_{FLAG}/ * s/sysfs_type()/kernfs_type()/ * s/SD_DEACTIVATED_BIAS/KN_DEACTIVATED_BIAS/ This patch is strictly rename only and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-11kernfs: s/sysfs/kernfs/ in various data structuresTejun Heo
kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. This patch performs the following renames. * s/sysfs_open_dirent/kernfs_open_node/ * s/sysfs_open_file/kernfs_open_file/ * s/sysfs_inode_attrs/kernfs_iattrs/ * s/sysfs_addrm_cxt/kernfs_addrm_cxt/ * s/sysfs_super_info/kernfs_super_info/ * s/sysfs_info()/kernfs_info()/ * s/sysfs_open_dirent_lock/kernfs_open_node_lock/ * s/sysfs_open_file_mutex/kernfs_open_file_mutex/ * s/sysfs_of()/kernfs_of()/ This patch is strictly rename only and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-11kernfs: drop s_ prefix from kernfs_node membersTejun Heo
kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. s_ prefix for kernfs members is used inconsistently and a misnomer now. It's not like kernfs_node is used widely across the kernel making the ability to grep for the members particularly useful. Let's just drop the prefix. This patch is strictly rename only and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-11kernfs: s/sysfs_dirent/kernfs_node/ and rename its friends accordinglyTejun Heo
kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. This patch performs the following renames. * s/sysfs_elem_dir/kernfs_elem_dir/ * s/sysfs_elem_symlink/kernfs_elem_symlink/ * s/sysfs_elem_attr/kernfs_elem_file/ * s/sysfs_dirent/kernfs_node/ * s/sd/kn/ in kernfs proper * s/parent_sd/parent/ * s/target_sd/target/ * s/dir_sd/parent/ * s/to_sysfs_dirent()/rb_to_kn()/ * misc renames of local vars when they conflict with the above Because md, mic and gpio dig into sysfs details, this patch ends up modifying them. All are sysfs_dirent renames and trivial. While we can avoid these by introducing a dummy wrapping struct sysfs_dirent around kernfs_node, given the limited usage outside kernfs and sysfs proper, I don't think such workaround is called for. This patch is strictly rename only and doesn't introduce any functional difference. - mic / gpio renames were missing. Spotted by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Neil Brown <neilb@suse.de> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Ashutosh Dixit <ashutosh.dixit@intel.com> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-10sysfs: bail early from kernfs_file_mmap() to avoid spurious lockdep warningTejun Heo
This is v3.14 fix for the same issue that a8b14744429f ("sysfs: give different locking key to regular and bin files") addresses for v3.13. Due to the extensive kernfs reorganization in v3.14 branch, the same fix couldn't be ported as-is. The v3.13 fix was ignored while merging it into v3.14 branch. 027a485d12e0 ("sysfs: use a separate locking class for open files depending on mmap") assigned different lockdep key to sysfs_open_file->mutex depending on whether the file implements mmap or not in an attempt to avoid spurious lockdep warning caused by merging of regular and bin file paths. While this restored some of the original behavior of using different locks (at least lockdep is concerned) for the different clases of files. The restoration wasn't full because now the lockdep key assignment depends on whether the file has mmap or not instead of whether it's a regular file or not. This means that bin files which don't implement mmap will get assigned the same lockdep class as regular files. This is problematic because file_operations for bin files still implements the mmap file operation and checking whether the sysfs file actually implements mmap happens in the file operation after grabbing @sysfs_open_file->mutex. We still end up adding locking dependency from mmap locking to sysfs_open_file->mutex to the regular file mutex which triggers spurious circular locking warning. For v3.13, a8b14744429f ("sysfs: give different locking key to regular and bin files") fixed it by giving sysfs_open_file->mutex different lockdep keys depending on whether the file is regular or bin instead of whether mmap exists or not; however, due to the way sysfs is now layered behind kernfs, this approach is no longer viable. kernfs can tell whether a sysfs node has mmap implemented or not but can't tell whether a bin file from a regular one. This patch updates kernfs such that kernfs_file_mmap() checks SYSFS_FLAG_HAS_MMAP and bail before grabbing sysfs_open_file->mutex so that it doesn't add spurious locking dependency from mmap to sysfs_open_file->mutex and changes sysfs so that it specifies kernfs_ops->mmap iff the sysfs file implements mmap. Combined, this ensures that sysfs_open_file->mutex is grabbed under mmap path iff the sysfs file actually implements mmap. As sysfs_open_file->mutex is already given a different lockdep key if mmap is implemented, this removes the spurious locking dependency. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@redhat.com> Link: http://lkml.kernel.org/g/20131203184324.GA11320@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: move file core code to fs/kernfs/file.cTejun Heo
Move core file code to fs/kernfs/file.c. fs/sysfs/file.c now contains sysfs kernfs_ops callbacks, sysfs wrappers around kernfs interfaces, and sysfs_schedule_callback(). The respective declarations in fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h. This is pure relocation. v2: Refreshed on top of the v2 of "sysfs, kernfs: prepare read path for kernfs". v3: Refreshed on top of the v3 of "sysfs, kernfs: prepare read path for kernfs". Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: introduce kernfs[_find_and]_get() and kernfs_put()Tejun Heo
Introduce kernfs interface for finding, getting and putting sysfs_dirents. * sysfs_find_dirent() is renamed to kernfs_find_ns() and lockdep assertion for sysfs_mutex is added. * sysfs_get_dirent_ns() is renamed to kernfs_find_and_get(). * Macro inline dancing around __sysfs_get/put() are removed and kernfs_get/put() are made proper functions implemented in fs/sysfs/dir.c. While the conversions are mostly equivalent, there's one difference - kernfs_get() doesn't return the input param as its return value. This change is intentional. While passing through the input increases writability in some areas, it is unnecessary and has been shown to cause confusion regarding how the last ref is handled. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: revamp sysfs_dirent active_ref lockdep annotationTejun Heo
Currently, sysfs_dirent active_ref lockdep annotation uses attribute->[s]key as the lockdep key, which forces kernfs_create_file_ns() to assume that sysfs_dirent->priv is pointing to a struct attribute which may not be true for non-sysfs users. This patch restructures the lockdep annotation such that * kernfs_ops contains lockdep_key which is used by default for files created kernfs_create_file_ns(). * kernfs_create_file_ns_key() is introduced which takes an extra @key argument. The created file will use the specified key for active_ref lockdep annotation. If NULL is specified, lockdep for the file is disabled. * sysfs_add_file_mode_ns() is updated to use kernfs_create_file_ns_key() with the appropriate key from the attribute or NULL if ignore_lockdep is set. This makes the lockdep annotation properly contained in kernfs while allowing sysfs to cleanly keep its current behavior. This patch doesn't introduce any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: introduce kernfs_notify()Tejun Heo
Introduce kernfs interface to wake up poll(2) which takes and returns sysfs_dirents. sysfs_notify_dirent() is renamed to kernfs_notify() and sysfs_notify() is updated so that it doesn't directly grab sysfs_mutex but acquires the target sysfs_dirents using sysfs_get_dirent(). sysfs_notify_dirent() is reimplemented as a dumb inline wrapper around kernfs_notify(). This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: add kernfs_ops->seq_{start|next|stop}()Tejun Heo
kernfs_ops currently only supports single_open() behavior which is pretty restrictive. Add optional callbacks ->seq_{start|next|stop}() which, when implemented, are invoked for seq_file traversal. This allows full seq_file functionality for kernfs users. This currently doesn't have any user and doesn't change any behavior. v2: Refreshed on top of the updated "sysfs, kernfs: prepare read path for kernfs". Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: remove sysfs_add_one()Tejun Heo
sysfs_add_one() is a wrapper around __sysfs_add_one() which prints out duplicate name warning if __sysfs_add_one() fails with -EEXIST. The previous kernfs conversions moved all dup warnings to sysfs interface functions and sysfs_add_one() doesn't have any user left. Remove sysfs_add_one() and update __sysfs_add_one() to take its name. This patch doesn't make any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: introduce kernfs_create_file[_ns]()Tejun Heo
Introduce kernfs interface to create a file which takes and returns sysfs_dirents. The actual file creation part is separated out from sysfs_add_file_mode_ns() into kernfs_create_file_ns(). The former now only decides the kernfs_ops to use and the file's size and invokes the latter. This patch doesn't introduce behavior changes. v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: remove SYSFS_KOBJ_BIN_ATTRTejun Heo
After kernfs_ops and sysfs_dirent->s_attr.size addition, the distinction between SYSFS_KOBJ_BIN_ATTR and SYSFS_KOBJ_ATTR is only necessary while creating files to decide which kernfs_ops to use. Afterwards, they behave exactly the same. This patch removes SYSFS_KOBJ_BIN_ATTR along with sysfs_is_bin(). sysfs_add_file[_mode_ns]() are updated to take bool @is_bin instead of @type. This patch doesn't introduce any behavior changes. This completely isolates the distinction between the two sysfs file types in the sysfs layer proper. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: add sysfs_dirent->s_attr.sizeTejun Heo
sysfs sets the size of regular files unconditionally at PAGE_SIZE and takes the size of bin files from bin_attribute. The latter is a pretty bad interface which forces bin_attribute users to create a separate copy of bin_attribute for each instance of the file - e.g. pci resource files. Add sysfs_dirent->s_attr.size so that the size can be specified separately. This unifies inode init paths of ATTR and BIN_ATTR identical and allows for generic size handling for kernfs. Unfortunately, this grows the size of sysfs_dirent by sizeof(loff_t). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: introduce kernfs_opsTejun Heo
We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: move sysfs_open_file to include/linux/kernfs.hTejun Heo
sysfs_open_file will be used as the primary handle for kernfs methods. Move its definition from fs/sysfs/file.c to include/linux/kernfs.h and mark the public and private fields. This is pure relocation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: prepare open, release, poll paths for kernfsTejun Heo
We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch prepares the rest - open, release and poll. There isn't much to do. Just renaming is enough. As sysfs_file_operations and sysfs_bin_operations are identical now, use the same file_operations for both - kernfs_file_operations. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: prepare mmap path for kernfsTejun Heo
We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges mmap path so that the kernfs and sysfs parts are separate. sysfs_kf_bin_mmap() which handles the interaction with bin_attribute mmap method is factored out of sysfs_bin_mmap(), which is renamed to kernfs_file_mmap(). All vma ops are renamed accordingly. sysfs_bin_mmap() is updated such that it can be used for both file types. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: prepare write path for kernfsTejun Heo
We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges write path so that the kernfs and sysfs parts are separate. kernfs_file_write() handles all boilerplate work including buffer management and locking and invokes sysfs_kf_write() or sysfs_kf_bin_write() depending on the file type which deals with the interaction with kobj store or bin_attribute write method. While this patch changes the order of some operations, it shouldn't change any visible behavior. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: prepare read path for kernfsTejun Heo
We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges read path so that the kernfs and sysfs parts are separate. * Regular file read path is refactored such that kernfs_seq_start/next/stop/show() handle all the boilerplate work including locking and updating event count for poll, while sysfs_kf_seq_show() deals with interaction with kobj show method. * Bin file read path is refactored such that kernfs_file_direct_read() handles all the boilerplate work including buffer management and locking, while sysfs_kf_bin_read() deals with interaction with bin_attribute read method. kernfs_file_read() is added. It invokes either the seq_file or direct read path depending on the file type. This will eventually allow using the same file_operations for both file types, which is necessary to separate out kernfs. While this patch changes the order of some operations, it shouldn't change any visible behavior. v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show(). Add comments explaining single_open() behavior. Both suggested by Pavel. v3: seq_stop() is called even after seq_start() failed. kernfs_seq_start() updated so that it doesn't unlock sysfs_open_file->mutex on failure so that kernfs_seq_stop() doesn't try to unlock an already unlocked mutex. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29sysfs, kernfs: replace sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with ↵Tejun Heo
->priv A directory sysfs_dirent points to the associated kobj. A regular or bin file points to the associated [bin_]attribute. This patch replaces sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with void * ->priv. This is to prepare for kernfs interface so that sysfs can specify the private data in the same way for directories and files. This lower debuggability but not by much - the whole thing was overlaid in a union anyway. If debuggability becomes an issue, we can later add ->priv accessors which explicitly check for the sysfs_dirent type and performs casting. This patch doesn't introduce any behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-27Merge branch 'driver-core-linus' into driver-core-nextGreg Kroah-Hartman
We need those sysfs fixes in this branch to make testing, and future patches apply properly. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-27sysfs, kernfs: introduce kernfs_setattr()Tejun Heo
Introduce kernfs setattr interface - kernfs_setattr(). sysfs_sd_setattr() is renamed to __kernfs_setattr() and kernfs_setattr() is a simple wrapper around it with sysfs_mutex locking. sysfs_chmod_file() is updated to get an explicit ref on kobj->sd and then invoke kernfs_setattr() so that it doesn't have to use internal interface. This patch doesn't introduce any behavior differences. v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-27sysfs, kernfs: introduce kernfs_remove[_by_name[_ns]]()Tejun Heo
Introduce kernfs removal interfaces - kernfs_remove() and kernfs_remove_by_name[_ns](). These are just renames of sysfs_remove() and sysfs_hash_and_remove(). No functional changes. v2: Dummy kernfs_remove_by_name_ns() for !CONFIG_SYSFS updated to return -ENOSYS instead of 0. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-23sysfs: use a separate locking class for open files depending on mmapTejun Heo
The following two commits implemented mmap support in the regular file path and merged bin file support into the regular path. 73d9714627ad ("sysfs: copy bin mmap support from fs/sysfs/bin.c to fs/sysfs/file.c") 3124eb1679b2 ("sysfs: merge regular and bin file handling") After the merge, the following commands trigger a spurious lockdep warning. "test-mmap-read" simply mmaps the file and dumps the content. $ cat /sys/block/sda/trace/act_mask $ test-mmap-read /sys/devices/pci0000\:00/0000\:00\:03.0/resource0 4096 ====================================================== [ INFO: possible circular locking dependency detected ] 3.12.0-work+ #378 Not tainted ------------------------------------------------------- test-mmap-read/567 is trying to acquire lock: (&of->mutex){+.+.+.}, at: [<ffffffff8120a8df>] sysfs_bin_mmap+0x4f/0x120 but task is already holding lock: (&mm->mmap_sem){++++++}, at: [<ffffffff8114b399>] vm_mmap_pgoff+0x49/0xa0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&mm->mmap_sem){++++++}: ... -> #2 (sr_mutex){+.+.+.}: ... -> #1 (&bdev->bd_mutex){+.+.+.}: ... -> #0 (&of->mutex){+.+.+.}: ... other info that might help us debug this: Chain exists of: &of->mutex --> sr_mutex --> &mm->mmap_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(sr_mutex); lock(&mm->mmap_sem); lock(&of->mutex); *** DEADLOCK *** 1 lock held by test-mmap-read/567: #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8114b399>] vm_mmap_pgoff+0x49/0xa0 stack backtrace: CPU: 3 PID: 567 Comm: test-mmap-read Not tainted 3.12.0-work+ #378 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 ffffffff81ed41a0 ffff880009441bc8 ffffffff81611ad2 ffffffff81eccb80 ffff880009441c08 ffffffff8160f215 ffff880009441c60 ffff880009c75208 0000000000000000 ffff880009c751e0 ffff880009c75208 ffff880009c74ac0 Call Trace: [<ffffffff81611ad2>] dump_stack+0x4e/0x7a [<ffffffff8160f215>] print_circular_bug+0x2b0/0x2bf [<ffffffff8109ca0a>] __lock_acquire+0x1a3a/0x1e60 [<ffffffff8109d6ba>] lock_acquire+0x9a/0x1d0 [<ffffffff81615547>] mutex_lock_nested+0x67/0x3f0 [<ffffffff8120a8df>] sysfs_bin_mmap+0x4f/0x120 [<ffffffff8115d363>] mmap_region+0x3b3/0x5b0 [<ffffffff8115d8ae>] do_mmap_pgoff+0x34e/0x3d0 [<ffffffff8114b3ba>] vm_mmap_pgoff+0x6a/0xa0 [<ffffffff8115be3e>] SyS_mmap_pgoff+0xbe/0x250 [<ffffffff81008282>] SyS_mmap+0x22/0x30 [<ffffffff8161a4d2>] system_call_fastpath+0x16/0x1b This happens because one file nests sr_mutex, which nests mm->mmap_sem under it, under of->mutex while mmap implementation naturally nests of->mutex under mm->mmap_sem. The warning is false positive as of->mutex is per open-file and the two paths belong to two different files. This warning didn't trigger before regular and bin file supports were merged because only bin file supported mmap and the other side of locking happened only on regular files which used equivalent but separate locking. It'd be best if we give separate locking classes per file but we can't easily do that. Let's differentiate on ->mmap() for now. Later we'll add explicit file operations struct and can add per-ops lockdep key there. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-01sysfs: use generic_file_llseek() for sysfs_file_operationsTejun Heo
13c589d5b0ac6 ("sysfs: use seq_file when reading regular files") converted regular sysfs files to use seq_file. The commit substituted generic_file_llseek() with seq_lseek() for llseek implementation. Before the change, all regular sysfs files were allowed to seek to any position in [0, PAGE_SIZE] as the file size is always PAGE_SIZE and generic_file_llseek() allows any seeking inside the range under file size; however, seq_lseek()'s behavior is different. It traverses the output by repeatedly invoking ->show() until it reaches the target offset or traversal indicates EOF. As seq_files are fully dynamic and may not end at all, it doesn't support seeking from the end (SEEK_END). Apparently, there are userland tools which uses SEEK_END to discover the buffer size to use and the switch to seq_lseek() disturbs them as SEEK_END fails with -EINVAL. The only benefits of using seq_lseek() instead of generic_file_llseek() are * Early failure. If traversing to certain file position should fail, seq_lseek() will report such failures on lseek(2) instead of the following read/write operations. * EOF detection. While SEEK_END is not supported, SEEK_SET/CUR + large offset can be used to detect eof - eof at the time of the seek anyway as the file size may change dynamically. Both aren't necessary for sysfs or prospect kernfs users. Revert to genefic_file_llseek() and preserve the original behavior. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Link: https://lkml.kernel.org/r/20131031114358.GA5551@osiris Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-30sysfs: return correct error code on unimplemented mmap()Vladimir Zapolskiy
Both POSIX.1-2008 and Linux Programmer's Manual have a dedicated return error code for a case, when a file doesn't support mmap(), it's ENODEV. This change replaces overloaded EINVAL with ENODEV in a situation described above for sysfs binary files. Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-29sysfs: merge sysfs_elem_bin_attr into sysfs_elem_attrTejun Heo
3124eb1679 ("sysfs: merge regular and bin file handling") folded bin file handling into regular file handling. Among other things, bin file now shares the same open path including sysfs_open_dirent association using sysfs_dirent->s_attr.open. This is buggy because ->s_bin_attr lives in the same union and doesn't have the field. This bug doesn't trigger because sysfs_elem_bin_attr doesn't have an active field at the conflicting position. It does have a field "buffers" but it isn't used anymore. This patch collapses sysfs_elem_bin_attr into sysfs_elem_attr so that the bin_attr is accessed through ->s_attr.bin_attr which lives with ->s_attr.attr in an anonymous union. The code paths already assume bin_attr contains attr as the first element, so this doesn't add any more assumptions while making it explicit that the two types are handled together. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-25sysfs: fix sysfs_write_file for bin fileMing Lei
Before patch(sysfs: prepare path write for unified regular / bin file handling), when size of bin file is zero, writting still can continue, but this patch changes the behaviour. The worse thing is that firmware loader is broken by this patch, and user space application can't write to firmware bin file any more because both firmware loader and drivers can't know at advance how large the firmware file is and have to set its initialized size as zero. This patch fixes the problem and keeps behaviour of writting to bin as before. Reported-by: Lothar Waßmann <LW@karo-electronics.de> Tested-by: Lothar Waßmann <LW@karo-electronics.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-14sysfs/bin: Fix size handling overflow for bin_attributeBenjamin Herrenschmidt
While looking at the code, I noticed that bin_attribute read() and write() ops copy the inode size into an int for futher comparisons. Some bin_attributes can be fairly large. For example, pci creates some for BARs set to the BAR size and giant BARs are around the corner, so this is going to break something somewhere eventually. Let's use the right type. [adjust for seqfile conversions, only needed for bin_read() - gkh] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-14sysfs: make sysfs_file_ops() follow ignore_lockdep flagTejun Heo
375b611e60 ("sysfs: remove sysfs_buffer->ops") introduced sysfs_file_ops() which determines the associated file operation of a given sysfs_dirent. As file ops access should be protected by an active reference, the new function includes a lockdep assertion on the sysfs_dirent; unfortunately, I forgot to take attr->ignore_lockdep flag into account and the lockdep assertion trips spuriously for files which opt out from active reference lockdep checking. # cat /sys/devices/pci0000:00/0000:00:01.2/usb1/authorized ------------[ cut here ]------------ WARNING: CPU: 1 PID: 540 at /work/os/work/fs/sysfs/file.c:79 sysfs_file_ops+0x4e/0x60() Modules linked in: CPU: 1 PID: 540 Comm: cat Not tainted 3.11.0-work+ #3 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000009 ffff880016205c08 ffffffff81ca0131 0000000000000000 ffff880016205c40 ffffffff81096d0d ffff8800166cb898 ffff8800166f6f60 ffffffff8125a220 ffff880011ab1ec0 ffff88000aff0c78 ffff880016205c50 Call Trace: [<ffffffff81ca0131>] dump_stack+0x4e/0x82 [<ffffffff81096d0d>] warn_slowpath_common+0x7d/0xa0 [<ffffffff81096dea>] warn_slowpath_null+0x1a/0x20 [<ffffffff8125994e>] sysfs_file_ops+0x4e/0x60 [<ffffffff8125a274>] sysfs_open_file+0x54/0x300 [<ffffffff811df612>] do_dentry_open.isra.17+0x182/0x280 [<ffffffff811df820>] finish_open+0x30/0x40 [<ffffffff811f0623>] do_last+0x503/0xd90 [<ffffffff811f0f6b>] path_openat+0xbb/0x6d0 [<ffffffff811f23ba>] do_filp_open+0x3a/0x90 [<ffffffff811e09a9>] do_sys_open+0x129/0x220 [<ffffffff811e0abe>] SyS_open+0x1e/0x20 [<ffffffff81caf3c2>] system_call_fastpath+0x16/0x1b ---[ end trace aa48096b111dafdb ]--- Rename fs/sysfs/dir.c::ignore_lockdep() to sysfs_ignore_lockdep() and move it to fs/sysfs/sysfs.h and make sysfs_file_ops() skip lockdep assertion if sysfs_ignore_lockdep() is true. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: merge regular and bin file handlingTejun Heo
With the previous changes, sysfs regular file code is ready to handle bin files too. This patch makes bin files share the regular file path. * sysfs_create/remove_bin_file() are moved to fs/sysfs/file.c. * sysfs_init_inode() is updated to use the new sysfs_bin_operations instead of bin_fops for bin files. * fs/sysfs/bin.c and the related pieces are removed. This patch shouldn't introduce any behavior difference to bin file accesses. Overall, this unification reduces the amount of duplicate logic, makes behaviors more consistent and paves the road for building simpler and more versatile interface which will allow other subsystems to make use of sysfs for their pseudo filesystems. v2: Stale fs/sysfs/bin.c reference dropped from Documentation/DocBook/filesystems.tmpl. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay@vrfy.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: prepare open path for unified regular / bin file handlingTejun Heo
sysfs bin file handling will be merged into the regular file support. This patch prepares the open path. This patch updates sysfs_open_file() such that it can handle both regular and bin files. This is a preparation and the new bin file path isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: copy bin mmap support from fs/sysfs/bin.c to fs/sysfs/file.cTejun Heo
sysfs bin file handling will be merged into the regular file support. This patch copies mmap support from bin so that fs/sysfs/file.c can handle mmapping bin files. The code is copied mostly verbatim with the following updates. * ->mmapped and ->vm_ops are added to sysfs_open_file and bin_buffer references are replaced with sysfs_open_file ones. * Symbols are prefixed with sysfs_. * sysfs_unmap_bin_file() grabs sysfs_open_dirent and traverses ->files. Invocation of this function is added to sysfs_addrm_finish(). * sysfs_bin_mmap() is added to sysfs_bin_operations. This is a preparation and the new mmap path isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: add sysfs_bin_read()Tejun Heo
sysfs bin file handling will be merged into the regular file support. This patch prepares the read path. Copy fs/sysfs/bin.c::read() to fs/sysfs/file.c and make it use sysfs_open_file instead of bin_buffer. The function is identical copy except for the use of sysfs_open_file. The new function is added to sysfs_bin_operations. This isn't used yet but will eventually replace fs/sysfs/bin.c. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: prepare path write for unified regular / bin file handlingTejun Heo
sysfs bin file handling will be merged into the regular file support. This patch prepares the write path. bin file write is almost identical to regular file write except that the write length is capped by the inode size and @off is passed to the write method. This patch adds bin file handling to sysfs_write_file() so that it can handle both regular and bin files. A new file_operations struct sysfs_bin_operations is added, which currently only hosts sysfs_write_file() and generic_file_llseek(). This isn't used yet but will eventually replace fs/sysfs/bin.c. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: use seq_file when reading regular filesTejun Heo
sysfs read path implements its own buffering scheme between userland and kernel callbacks, which essentially is a degenerate duplicate of seq_file. This patch replaces the custom read buffering implementation in sysfs with seq_file. While the amount of code reduction is small, this reduces low level hairiness and enables future development of a new versatile API based on seq_file so that sysfs features can be shared with other subsystems. As write path was already converted to not use sysfs_open_file->page, this patch makes ->page and ->count unused and removes them. Userland behavior remains the same except for some extreme corner cases - e.g. sysfs will now regenerate the content each time a file is read after a non-contiguous seek whereas the original code would keep using the same content. While this is a userland visible behavior change, it is extremely unlikely to be noticeable and brings sysfs behavior closer to that of procfs. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: use transient write bufferTejun Heo
There isn't much to be gained by keeping around kernel buffer while a file is open especially as the read path planned to be converted to use seq_file and won't use the buffer. This patch makes sysfs_write_file() use per-write transient buffer instead of sysfs_open_file->page. This simplifies the write path, enables removing sysfs_open_file->page once read path is updated and will help merging bin file write path which already requires the use of a transient buffer due to a locking order issue. As the function comments of flush_write_buffer() and sysfs_write_buffer() are being updated anyway, reformat them so that they're more conventional. v2: Use min_t() instead of min() in sysfs_write_file() to avoid build warning on arm. Reported by build test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: add sysfs_open_file->sd and ->fileTejun Heo
sysfs will be converted to use seq_file for read path, which will make it difficult to pass around multiple pointers directly. This patch adds sysfs_open_file->sd and ->file so that we can reach all the necessary data structures from sysfs_open_file. flush_write_buffer() is updated to drop @dentry which was used to discover the sysfs_dirent as it's now available through sysfs_open_file->sd. This patch doesn't cause any behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-05sysfs: rename sysfs_buffer to sysfs_open_fileTejun Heo
sysfs read path will be converted to use seq_file which will handle buffering making sysfs_buffer a misnomer. Rename sysfs_buffer to sysfs_open_file, and sysfs_open_dirent->buffers to ->files. This path is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>