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5f820f648c
linux/fs
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Tejun Heo 5f820f648c poll: allow f_op->poll to sleep 
f_op->poll is the only vfs operation which is not allowed to sleep.  It's
because poll and select implementation used task state to synchronize
against wake ups, which doesn't have to be the case anymore as wait/wake
interface can now use custom wake up functions.  The non-sleep restriction
can be a bit tricky because ->poll is not called from an atomic context
and the result of accidentally sleeping in ->poll only shows up as
temporary busy looping when the timing is right or rather wrong.

This patch converts poll/select to use custom wake up function and use
separate triggered variable to synchronize against wake up events.  The
only added overhead is an extra function call during wake up and
negligible.

This patch removes the one non-sleep exception from vfs locking rules and
is beneficial to userland filesystem implementations like FUSE, 9p or
peculiar fs like spufs as it's very difficult for those to implement
non-sleeping poll method.

While at it, make the following cosmetic changes to make poll.h and
select.c checkpatch friendly.

* s/type * symbol/type *symbol/		   : three places in poll.h
* remove blank line before EXPORT_SYMBOL() : two places in select.c

Oleg: spotted missing barrier in poll_schedule_timeout()
Davide: spotted missing write barrier in pollwake()

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Brad Boyer <flar@allandria.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Roland McGrath <roland@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-06 15:59:12 -08:00
..
9p Merge branch 'next' into for-linus 2008-12-25 11:40:09 +11:00
adfs
affs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-01-05 18:32:06 -08:00
afs fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
autofs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
autofs4 zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
befs befs: ensure fast symlinks are NUL-terminated 2008-12-31 18:07:40 -05:00
bfs CRED: Wrap task credential accesses in the BFS filesystem 2008-11-14 10:38:47 +11:00
cifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-01-05 18:32:06 -08:00
coda add a vfs_fsync helper 2009-01-05 11:54:28 -05:00
configfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
cramfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
debugfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
devpts zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
dlm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm 2009-01-05 19:02:09 -08:00
ecryptfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-01-05 18:32:06 -08:00
efs
exportfs Merge branch 'next' into for-linus 2008-12-25 11:40:09 +11:00
ext2 nfsd race fixes: ext2 2008-12-31 18:07:43 -05:00
ext3 ext3: Add default allocation routines for quota structures 2009-01-05 08:40:25 -08:00
ext4 ext4: Add default allocation routines for quota structures 2009-01-05 08:40:26 -08:00
fat Merge git://git.kernel.org/pub/scm/linux/kernel/git/hirofumi/fatfs-2.6 2008-12-30 20:33:34 -08:00
freevxfs freevxfs: ensure fast symlinks are NUL-terminated 2008-12-31 18:07:40 -05:00
fuse fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
gfs2 GFS2: Use DEFINE_SPINLOCK 2009-01-05 07:45:02 +00:00
hfs CRED: Wrap task credential accesses in the HFS filesystem 2008-11-14 10:38:54 +11:00
hfsplus CRED: Wrap task credential accesses in the HFSplus filesystem 2008-11-14 10:38:54 +11:00
hostfs fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
hpfs CRED: Wrap task credential accesses in the HPFS filesystem 2008-11-14 10:38:55 +11:00
hppfs CRED: Use creds in file structs 2008-11-14 10:39:25 +11:00
hugetlbfs hugetlb: unsigned ret cannot be negative 2009-01-06 15:59:08 -08:00
isofs isofs check for NULL ->i_op in root directory is dead code 2009-01-05 11:53:38 -05:00
jbd
jbd2 jbd2: Add buffer triggers 2009-01-05 08:40:30 -08:00
jffs2 fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
jfs fix the treatment of jfs special inodes 2009-01-05 11:54:29 -05:00
lockd Merge branch 'devel' into next 2008-12-30 16:51:43 -05:00
minix CRED: Wrap task credential accesses in the Minix filesystem 2008-11-14 10:38:57 +11:00
ncpfs CRED: Wrap task credential accesses in the NCPFS filesystem 2008-11-14 10:38:58 +11:00
nfs fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
nfs_common SUNRPC: nfsacl_encode/nfsacl_decode should be exported as GPL-only 2008-12-23 15:21:32 -05:00
nfsd add a vfs_fsync helper 2009-01-05 11:54:28 -05:00
nls
notify inotify: fix type errors in interfaces 2009-01-05 11:54:29 -05:00
ntfs ntfs: don't NULL i_op 2009-01-05 11:54:27 -05:00
ocfs2 Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2 2009-01-05 18:32:43 -08:00
omfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
openpromfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
partitions block/md: fix md autodetection 2008-11-18 15:08:56 +01:00
proc mm: report the MMU pagesize in /proc/pid/smaps 2009-01-06 15:58:58 -08:00
qnx4
ramfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
reiserfs Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2 2009-01-05 18:32:43 -08:00
romfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
smbfs fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
sysfs zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
sysv sysv: ensure fast symlinks are NUL-terminated 2008-12-31 18:07:39 -05:00
ubifs UBIFS: do not use WB_SYNC_HOLD 2009-01-06 15:59:09 -08:00
udf Merge branch 'master' into next 2008-12-04 17:16:36 +11:00
ufs CRED: Wrap task credential accesses in the UFS filesystem 2008-11-14 10:39:04 +11:00
xfs [XFS] Fix merge failures 2008-12-29 16:47:18 +11:00
aio.c aio: make the lookup_ioctx() lockless 2008-12-29 08:29:50 +01:00
anon_inodes.c anon_inodes: use fops->owner for module refcount 2008-12-31 16:55:44 +02:00
attr.c CRED: Wrap task credential accesses in the filesystem subsystem 2008-11-14 10:39:05 +11:00
bad_inode.c kill ->dir_notify() 2008-12-31 18:07:43 -05:00
binfmt_aout.c sanitize ifdefs in binfmt_aout 2009-01-03 11:45:54 -08:00
binfmt_elf_fdpic.c CRED: Make execve() take advantage of copy-on-write credentials 2008-11-14 10:39:24 +11:00
binfmt_elf.c Merge branch 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6 2008-12-28 12:33:21 -08:00
binfmt_em86.c
binfmt_flat.c CRED: Make execve() take advantage of copy-on-write credentials 2008-11-14 10:39:24 +11:00
binfmt_misc.c zero i_uid/i_gid on inode allocation 2009-01-05 11:54:28 -05:00
binfmt_script.c
binfmt_som.c CRED: Make execve() take advantage of copy-on-write credentials 2008-11-14 10:39:24 +11:00
bio-integrity.c bio: allow individual slabs in the bio_set 2008-12-29 08:29:23 +01:00
bio.c bio: get rid of bio_vec clearing 2008-12-29 08:29:53 +01:00
block_dev.c fs/block_dev.c: __read_mostly improvement and sb_is_blkdev_sb utilization 2008-12-31 18:07:43 -05:00
buffer.c block_write_begin(): remove useless goto 2009-01-06 15:59:08 -08:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c
compat.c CRED: Make execve() take advantage of copy-on-write credentials 2008-11-14 10:39:24 +11:00
dcache.c filp_cachep can be static in fs/file_table.c 2008-12-31 18:07:42 -05:00
dcookies.c shrink struct dentry 2008-12-31 18:07:38 -05:00
direct-io.c fs: truncate blocks outside i_size after O_DIRECT write error 2009-01-06 15:59:06 -08:00
dquot.c quota: Export dquot_alloc() and dquot_destroy() functions 2009-01-05 08:40:25 -08:00
drop_caches.c
eventfd.c
eventpoll.c epoll: introduce resource usage limits 2008-12-01 19:55:24 -08:00
exec.c fs/exec.c:__bprm_mm_init(): clean up error handling 2009-01-06 15:59:11 -08:00
fcntl.c Merge branch 'next' into for-linus 2008-12-25 11:40:09 +11:00
fifo.c
file_table.c filp_cachep can be static in fs/file_table.c 2008-12-31 18:07:42 -05:00
file.c
filesystems.c vfs: remove duplicate code in get_fs_type() 2009-01-05 11:54:29 -05:00
fs-writeback.c fs: sys_sync fix 2009-01-06 15:59:09 -08:00
generic_acl.c
inode.c mm: remove GFP_HIGHUSER_PAGECACHE 2009-01-06 15:59:01 -08:00
internal.h CRED: Make execve() take advantage of copy-on-write credentials 2008-11-14 10:39:24 +11:00
ioctl.c GFS2: Support for FIEMAP ioctl 2009-01-05 07:38:46 +00:00
ioprio.c CRED: Use RCU to access another task's creds and to release a task's own creds 2008-11-14 10:39:19 +11:00
Kconfig fs: use menuconfig to control the Misc. filesystems menu 2009-01-06 15:59:12 -08:00
Kconfig.binfmt
libfs.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-01-05 18:32:06 -08:00
locks.c CRED: Wrap task credential accesses in the filesystem subsystem 2008-11-14 10:39:05 +11:00
Makefile quota: Split off quota tree handling into a separate file 2009-01-05 08:40:21 -08:00
mbcache.c
mpage.c do_mpage_readpage(): remove useless clear_buffer_mapped() call 2009-01-06 15:59:01 -08:00
namei.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-01-05 18:32:06 -08:00
namespace.c fs/namespace.c: drop code after return 2008-12-31 18:07:38 -05:00
nfsctl.c pass a struct path * to may_open 2008-12-31 18:07:41 -05:00
no-block.c
open.c inode->i_op is never NULL 2009-01-05 11:54:28 -05:00
pipe.c sanitize audit_fd_pair() 2009-01-04 15:14:41 -05:00
pnode.c
pnode.h
posix_acl.c CRED: Wrap task credential accesses in the filesystem subsystem 2008-11-14 10:39:05 +11:00
quota_tree.c quota: Split off quota tree handling into a separate file 2009-01-05 08:40:21 -08:00
quota_tree.h quota: Split off quota tree handling into a separate file 2009-01-05 08:40:21 -08:00
quota_v1.c quota: Move quotaio_v[12].h from include/linux/ to fs/ 2009-01-05 08:36:58 -08:00
quota_v2.c quota: Convert union in mem_dqinfo to a pointer 2009-01-05 08:40:21 -08:00
quota.c quota: Introduce DQUOT_QUOTA_SYS_FILE flag 2009-01-05 08:36:57 -08:00
quotaio_v1.h quota: Move quotaio_v[12].h from include/linux/ to fs/ 2009-01-05 08:36:58 -08:00
quotaio_v2.h quota: Split off quota tree handling into a separate file 2009-01-05 08:40:21 -08:00
read_write.c vfs: lseek(fd, 0, SEEK_CUR) race condition 2009-01-05 11:53:07 -05:00
read_write.h
readdir.c
select.c poll: allow f_op->poll to sleep 2009-01-06 15:59:12 -08:00
seq_file.c Merge branch 'cpus4096-for-linus-3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-01-03 12:04:39 -08:00
signalfd.c
splice.c
stack.c
stat.c inode->i_op is never NULL 2009-01-05 11:54:28 -05:00
super.c security: pass mount flags to security_sb_kern_mount() 2008-12-20 09:02:39 +11:00
sync.c mm: do_sync_mapping_range integrity fix 2009-01-06 15:59:00 -08:00
timerfd.c
utimes.c
xattr_acl.c
xattr.c inode->i_op is never NULL 2009-01-05 11:54:28 -05:00