diff options
| author | Fan Du <fan.du@windriver.com> | 2013-04-30 15:27:27 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-11-28 14:02:00 +0000 |
| commit | 40b3183d5a1c19369c3c15b9bce144f2ccf330f0 (patch) | |
| tree | abfe4d4783705b667813a19c4ef79a4c88e97876 | |
| parent | b9662482043ed426ada7afbb406090bf0b9ebda8 (diff) | |
include/linux/fs.h: disable preempt when acquire i_size_seqcount write lock
commit 74e3d1e17b2e11d175970b85acd44f5927000ba2 upstream.
Two rt tasks bind to one CPU core.
The higher priority rt task A preempts a lower priority rt task B which
has already taken the write seq lock, and then the higher priority rt
task A try to acquire read seq lock, it's doomed to lockup.
rt task A with lower priority: call write
i_size_write rt task B with higher priority: call sync, and preempt task A
write_seqcount_begin(&inode->i_size_seqcount); i_size_read
inode->i_size = i_size; read_seqcount_begin <-- lockup here...
So disable preempt when acquiring every i_size_seqcount *write* lock will
cure the problem.
Signed-off-by: Fan Du <fan.du@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | include/linux/fs.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 9c426bd62ef..dd743859f04 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -911,9 +911,11 @@ static inline loff_t i_size_read(const struct inode *inode) static inline void i_size_write(struct inode *inode, loff_t i_size) { #if BITS_PER_LONG==32 && defined(CONFIG_SMP) + preempt_disable(); write_seqcount_begin(&inode->i_size_seqcount); inode->i_size = i_size; write_seqcount_end(&inode->i_size_seqcount); + preempt_enable(); #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT) preempt_disable(); inode->i_size = i_size; |