Messages in this thread | | | Date | Fri, 6 Sep 2013 10:52:52 +0200 | Subject | Re: linux-next: build warning after merge of the final tree (Linus' tree related - vai vfs tree) | From | Geert Uytterhoeven <> |
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On Fri, Sep 6, 2013 at 9:19 AM, Stephen Rothwell <sfr@canb.auug.org.au> wrote: > After merging the final tree, today's linux-next build (arm defconfig) > produced this warning: > > 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] > > This is: > > cmpxchg(&sb->s_dio_done_wq, NULL, wq); > > Introduced by commit 7b7a8665edd8 ("direct-io: Implement generic deferred > AIO completions").
This happens for include/asm-generic/cmpxchg.h and several other arch-specific implementations that cast the return value of cmpxchg() like
#define cmpxchg(ptr, o, n) ((__typeof__(*(ptr)))__cmpxchg(....
If the caller of cmpxchg() doesn't use the return value, we get a compiler warning, at least with some versions of gcc.
Any idea how to fix this once and for good?
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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