| Message ID | 20170316000859.25038-1-eric@engestrom.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thursday, 2017-03-16 00:08:59 +0000, Eric Engestrom wrote: > According to the kernel documentation: > Returns non-zero if @v was not @u, and zero otherwise. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100077 > Fixes: 63fc571863aa64683400 ("atomic: add atomic_add_unless()") > Signed-off-by: David Shao <davshao@gmail.com> > Reviewed-by: Eric Engestrom <eric@engestrom.ch> > Signed-off-by: Eric Engestrom <eric@engestrom.ch> That last s-o-b was added automatically, by mistake. I'll remove it when pushing this. This patch seems trivial to verify, can someone confirm this is right? /me is about ~94% sure, but doesn't know much about atomic ops and their return value convention. I checked the kernel and it does what libdrm does after this patch, so either one should be fixed; I'm assuming kernel is right and libdrm needs fixing, hence this patch. Cheers, Eric > --- > xf86atomic.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/xf86atomic.h b/xf86atomic.h > index 922b37da..ecb1ba86 100644 > --- a/xf86atomic.h > +++ b/xf86atomic.h > @@ -111,7 +111,7 @@ static inline int atomic_add_unless(atomic_t *v, int add, int unless) > c = atomic_read(v); > while (c != unless && (old = atomic_cmpxchg(v, c, c + add)) != c) > c = old; > - return c == unless; > + return c != unless; > } > > #endif > -- > Cheers, > Eric >
[+ Lionel] On 16 March 2017 at 16:46, Eric Engestrom <eric.engestrom@imgtec.com> wrote: > On Thursday, 2017-03-16 00:08:59 +0000, Eric Engestrom wrote: >> According to the kernel documentation: >> Returns non-zero if @v was not @u, and zero otherwise. >> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100077 >> Fixes: 63fc571863aa64683400 ("atomic: add atomic_add_unless()") >> Signed-off-by: David Shao <davshao@gmail.com> >> Reviewed-by: Eric Engestrom <eric@engestrom.ch> >> Signed-off-by: Eric Engestrom <eric@engestrom.ch> > > That last s-o-b was added automatically, by mistake. I'll remove it when > pushing this. > > This patch seems trivial to verify, can someone confirm this is right? > > /me is about ~94% sure, but doesn't know much about atomic ops and their > return value convention. > > I checked the kernel and it does what libdrm does after this patch, so > either one should be fixed; I'm assuming kernel is right and libdrm > needs fixing, hence this patch. > Changing the function matches the documentation, yet it doesn't [seem to] align with how it's used. I'm fairly sure that this will break libdrm_intel. Lionel, can you take a look at this patch please ? https://patchwork.freedesktop.org/patch/144252/ Emil
diff --git a/xf86atomic.h b/xf86atomic.h index 922b37da..ecb1ba86 100644 --- a/xf86atomic.h +++ b/xf86atomic.h @@ -111,7 +111,7 @@ static inline int atomic_add_unless(atomic_t *v, int add, int unless) c = atomic_read(v); while (c != unless && (old = atomic_cmpxchg(v, c, c + add)) != c) c = old; - return c == unless; + return c != unless; } #endif
According to the kernel documentation: Returns non-zero if @v was not @u, and zero otherwise. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100077 Fixes: 63fc571863aa64683400 ("atomic: add atomic_add_unless()") Signed-off-by: David Shao <davshao@gmail.com> Reviewed-by: Eric Engestrom <eric@engestrom.ch> Signed-off-by: Eric Engestrom <eric@engestrom.ch> --- xf86atomic.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)