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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>
This commit is contained in:
Darren Hart 2009-04-03 13:40:22 -07:00 committed by Thomas Gleixner
parent 8dac456a68
commit a72188d8a6
1 changed files with 8 additions and 4 deletions
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12
kernel/futex.c
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@ -1252,6 +1252,7 @@ handle_fault:
*/ */
#define FLAGS_SHARED 0x01 #define FLAGS_SHARED 0x01
#define FLAGS_CLOCKRT 0x02 #define FLAGS_CLOCKRT 0x02
#define FLAGS_HAS_TIMEOUT 0x04
static long futex_wait_restart(struct restart_block *restart); static long futex_wait_restart(struct restart_block *restart);
@ -1486,7 +1487,7 @@ retry_private:
restart->futex.val = val; restart->futex.val = val;
restart->futex.time = abs_time->tv64; restart->futex.time = abs_time->tv64;
restart->futex.bitset = bitset; restart->futex.bitset = bitset;
restart->futex.flags = 0; restart->futex.flags = FLAGS_HAS_TIMEOUT;
if (fshared) if (fshared)
restart->futex.flags |= FLAGS_SHARED; restart->futex.flags |= FLAGS_SHARED;
@ -1510,13 +1511,16 @@ static long futex_wait_restart(struct restart_block *restart)
{ {
u32 __user *uaddr = (u32 __user *)restart->futex.uaddr; u32 __user *uaddr = (u32 __user *)restart->futex.uaddr;
int fshared = 0; 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; restart->fn = do_no_restart_syscall;
if (restart->futex.flags & FLAGS_SHARED) if (restart->futex.flags & FLAGS_SHARED)
fshared = 1; 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.bitset,
restart->futex.flags & FLAGS_CLOCKRT); restart->futex.flags & FLAGS_CLOCKRT);
} }