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[PATCH] aio: don't ref kioctx after decref in put_ioctx 

put_ioctx's refcount debugging was doing an atomic_read after dropping its
reference when it wasn't the last ref, leaving a tiny race for another freeing
thread to sneak into.  This shifts the debugging before the ops, uses BUG_ON,
and reformats the defines a little.  Sadly, moving to inlines increased the
code size but this change decreases the code size by a whole 9 bytes :)

Signed-off-by: Zach Brown <zach.brown@oracle.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
hifive-unleashed-5.1
Zach Brown 2005-11-13 16:07:35 -08:00 committed by Linus Torvalds
parent d00689af6b
commit 5ef1c49f8f
1 changed files with 9 additions and 2 deletions
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11
include/linux/aio.h
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@ -210,8 +210,15 @@ struct kioctx *lookup_ioctx(unsigned long ctx_id);
int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
struct iocb *iocb));
#define get_ioctx(kioctx) do { if (unlikely(atomic_read(&(kioctx)->users) <= 0)) BUG(); atomic_inc(&(kioctx)->users); } while (0)
#define put_ioctx(kioctx) do { if (unlikely(atomic_dec_and_test(&(kioctx)->users))) __put_ioctx(kioctx); else if (unlikely(atomic_read(&(kioctx)->users) < 0)) BUG(); } while (0)
#define get_ioctx(kioctx) do { \
BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0)); \
atomic_inc(&(kioctx)->users); \
} while (0)
#define put_ioctx(kioctx) do { \
BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0)); \
if (unlikely(atomic_dec_and_test(&(kioctx)->users))) \
__put_ioctx(kioctx); \
} while (0)
#define in_aio() !is_sync_wait(current->io_wait)
/* may be used for debugging */