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2010-01-04sysfs: Add lockdep annotations for the sysfs active referenceEric W. Biederman
Holding locks over device_del -> kobject_del -> sysfs_deactivate can cause deadlocks if those same locks are grabbed in sysfs show or store methods. The I model s_active count + completion as a sleeping read/write lock. I describe to lockdep sysfs_get_active as a read_trylock, sysfs_put_active as a read_unlock, and sysfs_deactivate as a write_lock and write_unlock pair. This seems to capture the essence for purposes of finding deadlocks, and in my testing gives finds real issues and ignores non-issues. This brings us back to holding locks over kobject_del is a problem that ideally we should find a way of addressing, but at least lockdep can tell us about the problems instead of requiring developers to debug rare strange system deadlocks, that happen when sysfs files are removed while being written to. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-11sysfs: Factor out sysfs_rename from sysfs_rename_dir and sysfs_move_dirEric W. Biederman
These two functions do 90% of the same work and it doesn't significantly obfuscate the function to allow both the parent dir and the name to change at the same time. So merge them together to simplify maintenance, and increase testing. Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11sysfs: Propagate renames to the vfs on demandEric W. Biederman
By teaching sysfs_revalidate to hide a dentry for a sysfs_dirent if the sysfs_dirent has been renamed, and by teaching sysfs_lookup to return the original dentry if the sysfs dirent has been renamed. I can show the results of renames correctly without having to update the dcache during the directory rename. This massively simplifies the rename logic allowing a lot of weird sysfs special cases to be removed along with a lot of now unnecesary helper code. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11sysfs: Gut sysfs_addrm_start and sysfs_addrm_finishEric W. Biederman
With lazy inode updates and dentry operations bringing everything into sync on demand there is no longer any need to immediately update the vfs or grab i_mutex to protect those updates as we make changes to sysfs. Acked-by: Serge Hallyn <serue@us.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11sysfs: Implement sysfs_getattr & sysfs_permissionEric W. Biederman
With the implementation of sysfs_getattr and sysfs_permission sysfs becomes able to lazily propogate inode attribute changes from the sysfs_dirents to the vfs inodes. This paves the way for deleting significant chunks of now unnecessary code. While doing this we did not reference sysfs_setattr from sysfs_symlink_inode_operations so I added along with sysfs_getattr and sysfs_permission. Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11sysfs: Fix locking and factor out sysfs_sd_setattrEric W. Biederman
Cleanly separate the work that is specific to setting the attributes of a sysfs_dirent from what is needed to update the attributes of a vfs inode. Additionally grab the sysfs_mutex to keep any nasties from surprising us when updating the sysfs_dirent. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-09-10sysfs: Add labeling support for sysfsDavid P. Quigley
This patch adds a setxattr handler to the file, directory, and symlink inode_operations structures for sysfs. The patch uses hooks introduced in the previous patch to handle the getting and setting of security information for the sysfs inodes. As was suggested by Eric Biederman the struct iattr in the sysfs_dirent structure has been replaced by a structure which contains the iattr, secdata and secdata length to allow the changes to persist in the event that the inode representing the sysfs_dirent is evicted. Because sysfs only stores this information when a change is made all the optional data is moved into one dynamically allocated field. This patch addresses an issue where SELinux was denying virtd access to the PCI configuration entries in sysfs. The lack of setxattr handlers for sysfs required that a single label be assigned to all entries in sysfs. Granting virtd access to every entry in sysfs is not an acceptable solution so fine grained labeling of sysfs is required such that individual entries can be labeled appropriately. [sds: Fixed compile-time warnings, coding style, and setting of inode security init flags.] Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov> Signed-off-by: Stephen D. Smalley <sds@tycho.nsa.gov> Signed-off-by: James Morris <jmorris@namei.org>
2009-03-24sysfs: don't block indefinitely for unmapped files.Eric W. Biederman
Modify sysfs bin files so that we can remove the bin file while they are still mapped. When the kobject is removed we unmap the bin file and arrange for future accesses to the mapping to receive SIGBUS. Implementing this prevents a nasty DOS when pci devices are hot plugged and unplugged. Where if any of their resources were mmaped the kernel could not free up their pci resources or release their pci data structures. [akpm@linux-foundation.org: remove unused var] Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-03-24sysfs: reference sysfs_dirent from sysfs inodesEric W. Biederman
The sysfs_dirent serves as both an inode and a directory entry for sysfs. To prevent the sysfs inode numbers from being freed prematurely hold a reference to sysfs_dirent from the sysfs inode. [akpm@linux-foundation.org: add comment] Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Cc: Tejun Heo <tj@kernel.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-10-16sysfs: Support sysfs_notify from atomic context with new sysfs_notify_direntNeil Brown
Support sysfs_notify from atomic context with new sysfs_notify_dirent sysfs_notify currently takes sysfs_mutex. This means that it cannot be called in atomic context. sysfs_mutex is sometimes held over a malloc (sysfs_rename_dir) so it can block on low memory. In md I want to be able to notify on a sysfs attribute from atomic context, and I don't want to block on low memory because I could be in the writeout path for freeing memory. So: - export the "sysfs_dirent" structure along with sysfs_get, sysfs_put and sysfs_get_dirent so I can get the sysfs_dirent that I want to notify on and hold it in an md structure. - split sysfs_notify_dirent out of sysfs_notify so the sysfs_dirent can be notified on with no blocking (just a spinlock). Signed-off-by: Neil Brown <neilb@suse.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-21driver core: Suppress sysfs warnings for device_rename().Cornelia Huck
driver core: Suppress sysfs warnings for device_rename(). Renaming network devices to an already existing name is not something we want sysfs to print a scary warning for, since the callers can deal with this correctly. So let's introduce sysfs_create_link_nowarn() which gets rid of the common warning. Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-04-22[SCSI] sysfs: make group is_valid return a mode_tJames Bottomley
We have a problem in scsi_transport_spi in that we need to customise not only the visibility of the attributes, but also their mode. Fix this by making the is_visible() callback return a mode, with 0 indicating is not visible. Also add a sysfs_update_group() API to allow us to change either the visibility or mode of the files at any time on the fly. Acked-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-10-30sysfs: make sysfs_{get,put}_active() staticAdrian Bunk
sysfs_{get,put}_active() can now become static. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-17mm: bdi init hooksPeter Zijlstra
provide BDI constructor/destructor hooks [akpm@linux-foundation.org: compile fix] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-12sysfs: add copyrightsTejun Heo
Sysfs has gone through considerable amount of reimplementation. Add copyrights. Any objections? :-) Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: move sysfs file poll implementation to sysfs_open_direntTejun Heo
Sysfs file poll implementation is scattered over sysfs and kobject. Event numbering is done in sysfs_dirent but wait itself is done on kobject. This not only unecessarily bloats both kobject and sysfs_dirent but is also buggy - if a sysfs_dirent is removed while there still are pollers, the associaton betwen the kobject and sysfs_dirent breaks and kobject may be freed with the pollers still sleeping on it. This patch moves whole poll implementation into sysfs_open_dirent. Each time a sysfs_open_dirent is created, event number restarts from 1 and pollers sleep on sysfs_open_dirent. As event sequence number is meaningless without any open file and pollers should have open file and thus sysfs_open_dirent, this ephemeral event counting works and is a saner implementation. This patch fixes the dnagling sleepers bug and reduces the sizes of kobject and sysfs_dirent by one pointer. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: implement sysfs_open_direntTejun Heo
Implement sysfs_open_dirent which represents an open file (attribute) sysfs_dirent. A file sysfs_dirent with one or more open files have one sysfs_dirent and all sysfs_buffers (one for each open instance) are linked to it. sysfs_open_dirent doesn't actually do anything yet but will be used to off-load things which are specific for open file sysfs_dirent from it. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: move sysfs_dirent->s_children into sysfs_dirent->s_dirTejun Heo
Children list head is only meaninful for directory nodes. Move it into s_dir. This doesn't save any space currently but it will with further changes. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: make sysfs_root a regular directory direntTejun Heo
sysfs_root is different from a regular directory dirent in that it's of type SYSFS_ROOT and doesn't have a name. These differences aren't used by anybody and only adds to complexity. Make sysfs_root a regular directory dirent. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: make s_elem an anonymous unionTejun Heo
Make s_elem an anonymous union. Prefixing with s_elem makes things needlessly longer without any advantage. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: reposition sysfs_dirent->s_mode.Tejun Heo
Move s_mode downward such that it's side-by-side with s_iattr which is used for the same thing. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: clean up header filesTejun Heo
sysfs is about to go through major overhaul making this a pretty good opportunity to clean up (out-of-tree changes and pending patches will need regeneration anyway). Clean up headers. * Kill space between * and symbolname. * Move SYSFS_* type constants and flags into fs/sysfs/sysfs.h. They're internal to sysfs. * Reformat function prototypes and add argument symbol names. * Make dummy function definition order match that of function prototypes. * Add some comments. * Reorganize fs/sysfs/sysfs.h according to which file the declared variable or feature lives in. This patch does not introduce any behavior change. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: Remove s_dentryEric W. Biederman
The only uses of s_dentry left are the code that maintains s_dentry and trivial users that don't actually need it. So this patch removes the s_dentry maintenance code and restructures the trivial uses to use something else. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: Introduce sysfs_rename_mutexEric W. Biederman
Looking carefully at the rename code we have a subtle dependency that the structure of sysfs not change while we are performing a rename. If the parent directory of the object we are renaming changes while the rename is being performed nasty things could happen when we go to release our locks. So introduce a sysfs_rename_mutex to prevent this highly unlikely theoretical issue. In addition hold sysfs_rename_mutex over all calls to sysfs_get_dentry. Allowing sysfs_get_dentry to be simplified in the future. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: Make sysfs_mount staticEric W. Biederman
This patch modifies the users of sysfs_mount to use sysfs_root instead (which is what they are looking for). It then makes sysfs_mount static to keep people from using it by accident. The net result is slightly faster and cleaner code. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: Remove sysfs_instantiateEric W. Biederman
Now that sysfs_get_inode is dropping the inode lock we no longer have a need from sysfs_instantiate. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: make sysfs_addrm_finish() return voidTejun Heo
With the previous sysfs_add_one() update, there is only one user of the return value of sysfs_addrm_finish() and the user can switch to testing @sd easily. Make sysfs_addrm_finish() return void for cleaner semantics as suggested by Satyam Sharma. This patch doesn't introduce any noticeable behavior change. Signed-off-by: Tejun Heo <htejun@gmail.com> Cc: Satyam Sharma <satyam.sharma@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: make sysfs_add_one() automatically check for duplicate entryTejun Heo
Make sysfs_add_one() check for duplicate entry and return -EEXIST if such entry exists. This simplifies node addition code a bit. This patch doesn't introduce any noticeable behavior change. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: make sysfs_add/remove_one() call link/unlink_sibling() implictlyTejun Heo
When adding or removing a sysfs_dirent, the user used to be required to call link/unlink separately. It was for two reasons - code looked like that before sysfs_addrm_cxt conversion and to avoid looping through parent_sd->children list twice during removal. Performance optimization during removal just isn't worth it. Make sysfs_add/remove_one() call sysfs_link/unlink_sibing() implicitly. This makes code simpler albeit slightly less efficient. This change doesn't introduce any noticeable behavior change. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12sysfs: Remove first pass at shadow directory supportEric W. Biederman
While shadow directories appear to be a good idea, the current scheme of controlling their creation and destruction outside of sysfs appears to be a locking and maintenance nightmare in the face of sysfs directories dynamically coming and going. Which can now occur for directories containing network devices when CONFIG_SYSFS_DEPRECATED is not set. This patch removes everything from the initial shadow directory support that allowed the shadow directory creation to be controlled at a higher level. So except for a few bits of sysfs_rename_dir everything from commit b592fcfe7f06c15ec11774b5be7ce0de3aa86e73 is now gone. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-18sysfs: make sysfs_init_inode() staticTejun Heo
With sysfs_fill_super() converted to use sysfs_get_inode(), there is no user of sysfs_init_inode() outside of fs/sysfs/inode.c. Make it static. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: make directory dentries and inodes reclaimableTejun Heo
This patch makes dentries and inodes for sysfs directories reclaimable. * sysfs_notify() is modified to walk sysfs_dirent tree instead of dentry tree. * sysfs_update_file() and sysfs_chmod_file() use sysfs_get_dentry() to grab the victim dentry. * sysfs_rename_dir() and sysfs_move_dir() grab all dentries using sysfs_get_dentry() on startup. * Dentries for all shadowed directories are pinned in memory to serve as lookup start point. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: implement sysfs_get_dentry()Tejun Heo
Some sysfs operations require dentry and inode. sysfs_get_dentry() looks up and gets dentry for the specified sysfs_dirent. It finds the first ancestor with dentry attached and starts looking up dentries from there. Looking up from the nearest ancestor is necessary to support shadowed directories because we can't reliably lookup dentry for one of the shadows. Dentries for each shadow will be pinned in memory such that they can serve as the starting point for dentry lookup. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: move sysfs_drop_dentry() to dir.c and make it staticTejun Heo
After add/remove path restructuring, the only user of sysfs_drop_dentry() is sysfs_addrm_finish(). Move sysfs_drop_dentry() to dir.c and make it static. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: restructure add/remove paths and fix inode updateTejun Heo
The original add/remove code had the following problems. * parent's timestamps are updated on dentry instantiation. this is incorrect with reclaimable files. * updating parent's timestamps isn't synchronized. * parent nlink update assumes the inode is accessible which won't be true once directory dentries are made reclaimable. This patch restructures add/remove paths to resolve the above problems. Add/removal are done in the following steps. 1. sysfs_addrm_start() : acquire locks including sysfs_mutex and other resources. 2-a. sysfs_add_one() : add new sd. linking the new sd into the children list is caller's responsibility. 2-b. sysfs_remove_one() : remove a sd. unlinking the sd from the children list is caller's responsibility. 3. sysfs_addrm_finish() : release all resources and clean up. Steps 2-a and/or 2-b can be repeated multiple times. Parent's inode is looked up during sysfs_addrm_start(). If available (always at the moment), it's pinned and nlink is updated as sd's are added and removed. Timestamps are updated during finish if any sd has been added or removed. If parent's inode is not available during start, sysfs_mutex ensures that parent inode is not created till add/remove is complete. All the complexity is contained inside the helper functions. Especially, dentry/inode handling is properly hidden from the rest of sysfs which now mostly operate on sysfs_dirents. As an added bonus, codes which use these helpers to add and remove sysfs_dirents are now more structured and simpler. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: use sysfs_mutex to protect the sysfs_dirent treeTejun Heo
As kobj sysfs dentries and inodes are gonna be made reclaimable, i_mutex can't be used to protect sysfs_dirent tree. Use sysfs_mutex globally instead. As the whole tree is protected with sysfs_mutex, there is no reason to keep sysfs_rename_sem. Drop it. While at it, add docbook comments to functions which require sysfs_mutex locking. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: consolidate sysfs spinlocksTejun Heo
Replace sysfs_lock and kobj_sysfs_assoc_lock with sysfs_assoc_lock. sysfs_lock was originally to be used to protect sysfs_dirent tree but mutex seems better choice, so there is no reason to keep sysfs_lock separate. Merge the two spinlocks into one. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: make kobj point to sysfs_dirent instead of dentryTejun Heo
As kobj sysfs dentries and inodes are gonna be made reclaimable, dentry can't be used as naming token for sysfs file/directory, replace kobj->dentry with kobj->sd. The only external interface change is shadow directory handling. All other changes are contained in kobj and sysfs. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: implement sysfs_find_dirent() and sysfs_get_dirent()Tejun Heo
Implement sysfs_find_dirent() and sysfs_get_dirent(). sysfs_dirent_exist() is replaced by sysfs_find_dirent(). These will be used to make directory entries reclamiable. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: rename sysfs_dirent->s_type to s_flags and make room for flagsTejun Heo
Rename sysfs_dirent->s_type to s_flags, pack type into lower eight bits and reserve the rest for flags. sysfs_type() can used to access the type. All existing sd->s_type accesses are converted to use sysfs_type(). While at it, type test is changed to equality test instead of bit-and test where appropriate. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: use singly-linked list for sysfs_dirent treeTejun Heo
Make sysfs_dirent use singly linked list for its tree structure. sysfs_link_sibling() and sysfs_unlink_sibling() functions are added to handle simpler cases. It adds some complexity and cpu cycle overhead but reduced memory footprint is worthwhile on big machines. This change reduces the sizeof sysfs_dirent from 104 to 88 on 64bit and from 60 to 52 on 32bit. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: slim down sysfs_dirent->s_activeTejun Heo
Make sysfs_dirent->s_active an atomic_t instead of rwsem. This reduces the size of sysfs_dirent from 136 to 104 on 64bit and from 76 to 60 on 32bit with lock debugging turned off. With lock debugging turned on the reduction is much larger. s_active starts at zero and each active reference increments s_active. Putting a reference decrements s_active. Deactivation subtracts SD_DEACTIVATED_BIAS which is currently INT_MIN and assumed to be small enough to make s_active negative. If s_active is negative, sysfs_get() no longer grants new references. Deactivation succeeds immediately if there is no active user; otherwise, it waits using a completion for the last put. Due to the removal of lockdep tricks, this change makes things less trickier in release_sysfs_dirent(). As all the complexity is contained in three s_active functions, I think it's more readable this way. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: move s_active functions to fs/sysfs/dir.cTejun Heo
These functions are about to receive more complexity and doesn't really need to be inlined in the first place. Move them from fs/sysfs/sysfs.h to fs/sysfs/dir.c. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: use iget_locked() instead of new_inode()Tejun Heo
After dentry is reclaimed, sysfs always used to allocate new dentry and inode if the file is accessed again. This causes problem with operations which only pin the inode. For example, if inotify watch is added to a sysfs file and the dentry for the file is reclaimed, the next update event creates new dentry and new inode making the inotify watch miss all the events from there on. This patch fixes it by using iget_locked() instead of new_inode(). sysfs_new_inode() is renamed to sysfs_get_inode() and inode is initialized iff the inode is newly allocated. sysfs_instantiate() is responsible for unlocking new inodes. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: reorganize sysfs_new_indoe() and sysfs_create()Tejun Heo
Reorganize/clean up sysfs_new_inode() and sysfs_create(). * sysfs_init_inode() is separated out from sysfs_new_inode() and is responsible for basic initialization. * sysfs_instantiate() replaces the last step of sysfs_create() and is responsible for dentry instantitaion. * type-specific initialization is moved out to the callers. * mode is specified only once when creating a sysfs_dirent. * spurious list_del_init(&sd->s_sibling) dropped from create_dir() This change is to * prepare for inode allocation fix. * separate alloc and init code for synchronization update. * make dentry/inode initialization more flexible for later changes. This patch doesn't introduce visible behavior change. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: reimplement sysfs_drop_dentry()Tejun Heo
This patch reimplements sysfs_drop_dentry() such that remove_dir() can use it to drop dentry instead of using a separate mechanism. With this change, making directories reclaimable is much easier. This patch used to contain fixes for two race conditions around sd->s_dentry but that part has been separated out and included into mainline early as commit 6aa054aadfea613a437ad0b15d38eca2b963fc0a and dd14cbc994709a1c5a64ed3621f583c49a27e521. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: separate out sysfs_attach_dentry()Tejun Heo
Consolidate sd <-> dentry association into sysfs_attach_dentry() and call it after dentry and inode are properly set up. This is in preparation of sysfs_drop_dentry() updates. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: kill attribute file orphaningTejun Heo
Now that sysfs_dirent can be disconnected from kobject on deletion, there is no need to orphan each attribute files. All [bin_]attribute nodes are automatically orphaned when the parent node is deleted. Kill attribute file orphaning. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: implement sysfs_dirent active reference and immediate disconnectTejun Heo
sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11sysfs: reimplement symlink using sysfs_dirent treeTejun Heo
sysfs symlink is implemented by referencing dentry and kobject from sysfs_dirent - symlink entry references kobject, dentry is used to walk the tree. This complicates object lifetimes rules and is dangerous - for example, there is no way to tell to which module the target of a symlink belongs and referencing that kobject can make it linger after the module is gone. This patch reimplements symlink using only sysfs_dirent tree. sd for a symlink points and holds reference to the target sysfs_dirent and all walking is done using sysfs_dirent tree. Simpler and safer. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>