op 13-06-14 07:39, Michel Dänzer schreef:
On 12.06.2014 17:00, Maarten Lankhorst wrote:
I'm pretty sure that p_atomic_dec_zero should return 1 if the count
drops to zero.
Cc: "10.2 10.1 10.0" <mesa-sta...@lists.freedesktop.org>
I don't think the stable tag is justified: These bugs have been there
for more than four years. Nothing in Gallium can work properly if the
return value of p_atomic_dec_zero() is inverted, so if there was
significant use of the broken variants, we should have heard about it
long ago.
Yeah, they're just the fallbacks I guess.
Signed-off-by: Maarten Lankhorst <maarten.lankho...@canonical.com>
---
diff --git a/src/gallium/auxiliary/util/u_atomic.h
b/src/gallium/auxiliary/util/u_atomic.h
index 2f2b42b..08cadb4 100644
--- a/src/gallium/auxiliary/util/u_atomic.h
+++ b/src/gallium/auxiliary/util/u_atomic.h
@@ -183,7 +183,7 @@ p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
#define p_atomic_set(_v, _i) (*(_v) = (_i))
#define p_atomic_read(_v) (*(_v))
-#define p_atomic_dec_zero(_v) ((boolean) --(*(_v)))
+#define p_atomic_dec_zero(_v) (!(boolean) --(*(_v)))
Will this compile (with the intended result) without another set of parens?
Compiling the following in g++ and gcc seems to confirm it works correctly:
#include <stdio.h>
int main() {
int i = 1;
printf("dropped to 0: %i\n", (!(unsigned)--(*(&i))));
return 0;
}
Output:
dropped to 0: 1
@@ -324,7 +324,7 @@ p_atomic_dec_zero(int32_t *v)
{
uint32_t n = atomic_dec_32_nv((uint32_t *) v);
- return n != 0;
+ return n == 0;
}
This looks good, but there are more variants which look similarly broken?
Is this intended to be a question or a statement? The other p_atomic_dec_zero
definitions look fine afaict.
~Maarten
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