direct-io: Use return from cmpxchg to decide of assignment happened

Not using the return value can in the generic case be racy, so it's
in general good practice to check the return value instead.

This also resolved the warning caused on ARM and other architectures:

  fs/direct-io.c: In function 'sb_init_dio_done_wq':
  fs/direct-io.c:557:2: warning: value computed is not used [-Wunused-value]

Signed-off-by: Olof Johansson <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Russell King <[email protected]>
Cc: H Peter Anvin <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions