[CRIU] [PATCH 1/2] futex: Make raw value being s32

[Cyrill Gorcunov]

In case of error we do set futex value to
be negative one, this breaks waiting loops
and allow us to exit from program.

But during the futex conversion futex_wait_while_gt
was occasionally changed to u32 type making
error conditions to yield endless wait loop.

Change futex raw value to s32 to fix this.

Reported-by: Andrey Vagin <avagin at openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 include/lock.h |   22 +++++++++++-----------
 1 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/lock.h b/include/lock.h
index 6f77bfd..9d06da2 100644
--- a/include/lock.h
+++ b/include/lock.h
@@ -12,7 +12,7 @@
 #include "util.h"
 
 typedef struct {
-	u32	raw;
+	s32	raw;
 } futex_t;
 
 /* Get current futex @f value */
@@ -22,7 +22,7 @@ static inline u32 futex_get(futex_t *f)
 }
 
 /* Set futex @f value to @v */
-static inline void futex_set(futex_t *f, u32 v)
+static inline void futex_set(futex_t *f, s32 v)
 {
 	atomic_set(&f->raw, v);
 }
@@ -33,30 +33,30 @@ static inline void futex_set(futex_t *f, u32 v)
 #define futex_wait_if_cond(__f, __v, __cond)			\
 	do {							\
 		int ret;					\
-		u32 tmp;					\
+		s32 tmp;					\
 								\
 		while (1) {					\
 			tmp = (__f)->raw;			\
 			if (tmp __cond (__v))			\
 				break;				\
-			ret = sys_futex(&(__f)->raw, FUTEX_WAIT,\
+			ret = sys_futex((u32 *)&(__f)->raw, FUTEX_WAIT,\
 					tmp, NULL, NULL, 0);	\
 			BUG_ON(ret < 0 && ret != -EWOULDBLOCK);	\
 		}						\
 	} while (0)
 
 /* Set futex @f to @v and wake up all waiters */
-static inline void futex_set_and_wake(futex_t *f, u32 v)
+static inline void futex_set_and_wake(futex_t *f, s32 v)
 {
 	atomic_set(&f->raw, v);
-	BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
+	BUG_ON(sys_futex((u32 *)&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
 }
 
 /* Decrement futex @f value and wake up all waiters */
 static inline void futex_dec_and_wake(futex_t *f)
 {
 	atomic_dec(&f->raw);
-	BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
+	BUG_ON(sys_futex((u32 *)&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
 }
 
 /* Plain increment futex @f value */
@@ -66,18 +66,18 @@ static inline void futex_inc(futex_t *f) { f->raw++; }
 static inline void futex_dec(futex_t *f) { f->raw--; }
 
 /* Wait until futex @f value become @v */
-static inline void futex_wait_until(futex_t *f, u32 v)
+static inline void futex_wait_until(futex_t *f, s32 v)
 { futex_wait_if_cond(f, v, ==); }
 
 /* Wait while futex @f value is greater than @v */
-static inline void futex_wait_while_gt(futex_t *f, u32 v)
+static inline void futex_wait_while_gt(futex_t *f, s32 v)
 { futex_wait_if_cond(f, v, <=); }
 
 /* Wait while futex @f value is @v */
-static inline void futex_wait_while(futex_t *f, u32 v)
+static inline void futex_wait_while(futex_t *f, s32 v)
 {
 	while (f->raw == v) {
-		int ret = sys_futex(&f->raw, FUTEX_WAIT, v, NULL, NULL, 0);
+		int ret = sys_futex((u32 *)&f->raw, FUTEX_WAIT, v, NULL, NULL, 0);
 		BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
 	}
 }
-- 
1.7.7.6