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Commit 5ef1c49f authored by Zach Brown's avatar Zach Brown Committed by Linus Torvalds
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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: default avatarZach Brown <zach.brown@oracle.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d00689af

include/linux/aio.h

+9 −2
Original line number Diff line number Diff line
@@ -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 */