futex: add FUTEX_HAS_TIMEOUT flag to restart.futex.flags
Currently restart is only used if there is a timeout. The requeue_pi
functionality requires restarting to futex_lock_pi() on signal after
wakeup in futex_wait_requeue_pi() regardless of if there was a timeout
or not. Using 0 for the timeout value is confusing as that could
indicate an expired timer. The flag makes this explicit. While the
check is not technically needed in futex_wait_restart(), doing so
makes the code consistent with and will avoid confusion should the
need arise to restart wait without a timeout.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/futex.c b/kernel/futex.c
index af831fb..6b597cf 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1252,6 +1252,7 @@
*/
#define FLAGS_SHARED 0x01
#define FLAGS_CLOCKRT 0x02
+#define FLAGS_HAS_TIMEOUT 0x04
static long futex_wait_restart(struct restart_block *restart);
@@ -1486,7 +1487,7 @@
restart->futex.val = val;
restart->futex.time = abs_time->tv64;
restart->futex.bitset = bitset;
- restart->futex.flags = 0;
+ restart->futex.flags = FLAGS_HAS_TIMEOUT;
if (fshared)
restart->futex.flags |= FLAGS_SHARED;
@@ -1510,13 +1511,16 @@
{
u32 __user *uaddr = (u32 __user *)restart->futex.uaddr;
int fshared = 0;
- ktime_t t;
+ ktime_t t, *tp = NULL;
- t.tv64 = restart->futex.time;
+ if (restart->futex.flags & FLAGS_HAS_TIMEOUT) {
+ t.tv64 = restart->futex.time;
+ tp = &t;
+ }
restart->fn = do_no_restart_syscall;
if (restart->futex.flags & FLAGS_SHARED)
fshared = 1;
- return (long)futex_wait(uaddr, fshared, restart->futex.val, &t,
+ return (long)futex_wait(uaddr, fshared, restart->futex.val, tp,
restart->futex.bitset,
restart->futex.flags & FLAGS_CLOCKRT);
}
