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authorThomas Gleixner <tglx@linutronix.de>2008-11-20 10:02:53 -0800
committerThomas Gleixner <tglx@linutronix.de>2008-11-24 20:00:40 +0100
commit1acdac104668a0834cfa267de9946fac7764d486 (patch)
treebae8ffeb2425412c0bffbdf728b45104fe3178f2
parent3e1d7a6219ab64e13b10b1a77c0625db9a8bd8db (diff)
downloadop-kernel-dev-1acdac104668a0834cfa267de9946fac7764d486.zip
op-kernel-dev-1acdac104668a0834cfa267de9946fac7764d486.tar.gz
futex: make clock selectable for FUTEX_WAIT_BITSET
FUTEX_WAIT_BITSET could be used instead of FUTEX_WAIT by setting the bit set to FUTEX_BITSET_MATCH_ANY, but FUTEX_WAIT uses CLOCK_REALTIME while FUTEX_WAIT_BITSET uses CLOCK_MONOTONIC. Add a flag to select CLOCK_REALTIME for FUTEX_WAIT_BITSET so glibc can replace the FUTEX_WAIT logic which needs to do gettimeofday() calls before and after the syscall to convert the absolute timeout to a relative timeout for FUTEX_WAIT. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Ulrich Drepper <drepper@redhat.com>
-rw-r--r--include/linux/futex.h3
-rw-r--r--kernel/futex.c24
2 files changed, 19 insertions, 8 deletions
diff --git a/include/linux/futex.h b/include/linux/futex.h
index 8f627b9..3bf5bb5 100644
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -25,7 +25,8 @@ union ktime;
#define FUTEX_WAKE_BITSET 10
#define FUTEX_PRIVATE_FLAG 128
-#define FUTEX_CMD_MASK ~FUTEX_PRIVATE_FLAG
+#define FUTEX_CLOCK_REALTIME 256
+#define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)
#define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
#define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
diff --git a/kernel/futex.c b/kernel/futex.c
index e10c5c8..ba0d3b8 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1142,12 +1142,13 @@ handle_fault:
* In case we must use restart_block to restart a futex_wait,
* we encode in the 'flags' shared capability
*/
-#define FLAGS_SHARED 1
+#define FLAGS_SHARED 0x01
+#define FLAGS_CLOCKRT 0x02
static long futex_wait_restart(struct restart_block *restart);
static int futex_wait(u32 __user *uaddr, int fshared,
- u32 val, ktime_t *abs_time, u32 bitset)
+ u32 val, ktime_t *abs_time, u32 bitset, int clockrt)
{
struct task_struct *curr = current;
DECLARE_WAITQUEUE(wait, curr);
@@ -1233,8 +1234,10 @@ static int futex_wait(u32 __user *uaddr, int fshared,
slack = current->timer_slack_ns;
if (rt_task(current))
slack = 0;
- hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC,
- HRTIMER_MODE_ABS);
+ hrtimer_init_on_stack(&t.timer,
+ clockrt ? CLOCK_REALTIME :
+ CLOCK_MONOTONIC,
+ HRTIMER_MODE_ABS);
hrtimer_init_sleeper(&t, current);
hrtimer_set_expires_range_ns(&t.timer, *abs_time, slack);
@@ -1289,6 +1292,8 @@ static int futex_wait(u32 __user *uaddr, int fshared,
if (fshared)
restart->futex.flags |= FLAGS_SHARED;
+ if (clockrt)
+ restart->futex.flags |= FLAGS_CLOCKRT;
return -ERESTART_RESTARTBLOCK;
}
@@ -1312,7 +1317,8 @@ static long futex_wait_restart(struct restart_block *restart)
if (restart->futex.flags & FLAGS_SHARED)
fshared = 1;
return (long)futex_wait(uaddr, fshared, restart->futex.val, &t,
- restart->futex.bitset);
+ restart->futex.bitset,
+ restart->futex.flags & FLAGS_CLOCKRT);
}
@@ -1905,18 +1911,22 @@ void exit_robust_list(struct task_struct *curr)
long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
u32 __user *uaddr2, u32 val2, u32 val3)
{
- int ret = -ENOSYS;
+ int clockrt, ret = -ENOSYS;
int cmd = op & FUTEX_CMD_MASK;
int fshared = 0;
if (!(op & FUTEX_PRIVATE_FLAG))
fshared = 1;
+ clockrt = op & FUTEX_CLOCK_REALTIME;
+ if (clockrt && cmd != FUTEX_WAIT_BITSET)
+ return -ENOSYS;
+
switch (cmd) {
case FUTEX_WAIT:
val3 = FUTEX_BITSET_MATCH_ANY;
case FUTEX_WAIT_BITSET:
- ret = futex_wait(uaddr, fshared, val, timeout, val3);
+ ret = futex_wait(uaddr, fshared, val, timeout, val3, clockrt);
break;
case FUTEX_WAKE:
val3 = FUTEX_BITSET_MATCH_ANY;
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