Commit a72188d8 authored by Darren Hart's avatar Darren Hart Committed by Thomas Gleixner
Browse files

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: default avatarDarren Hart <dvhltc@us.ibm.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8dac456a

kernel/futex.c

+8 −4
Original line number Original line Diff line number Diff line
@@ -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;





	if (restart->futex.flags & FLAGS_HAS_TIMEOUT) {

		t.tv64 = restart->futex.time;

		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);

}

}

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