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nptl: Use FUTEX_LOCK_PI2 when available

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This patch uses the new futex PI operation provided by Linux v5.14
when it is required.

The futex_lock_pi64() is moved to futex-internal.c (since it used on
two different places and its code size might be large depending of the
kernel configuration) and clockid is added as an argument.

Co-authored-by: Kurt Kanzenbach <kurt@linutronix.de>
This commit is contained in:
Adhemerval Zanella 2021-06-25 10:11:00 +02:00
parent dd5adb515c
commit 8352b6df37
5 changed files with 72 additions and 56 deletions
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63
nptl/futex-internal.c
View File

@ -140,3 +140,66 @@ __futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
abstime, private, true);
}
libc_hidden_def (__futex_abstimed_wait_cancelable64)
int
__futex_lock_pi64 (int *futex_word, clockid_t clockid,
const struct __timespec64 *abstime, int private)
{
int err;
unsigned int clockbit = clockid == CLOCK_REALTIME
? FUTEX_CLOCK_REALTIME : 0;
int op_pi2 = __lll_private_flag (FUTEX_LOCK_PI2 | clockbit, private);
#if __ASSUME_FUTEX_LOCK_PI2
/* Assume __ASSUME_TIME64_SYSCALLS since FUTEX_LOCK_PI2 was added later. */
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op_pi2, 0, abstime);
#else
/* FUTEX_LOCK_PI does not support clock selection, so for CLOCK_MONOTONIC
the only option is to use FUTEX_LOCK_PI2. */
int op_pi1 = __lll_private_flag (FUTEX_LOCK_PI, private);
int op_pi = abstime != NULL && clockid != CLOCK_REALTIME ? op_pi2 : op_pi1;
# ifdef __ASSUME_TIME64_SYSCALLS
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op_pi, 0, abstime);
# else
bool need_time64 = abstime != NULL && !in_time_t_range (abstime->tv_sec);
if (need_time64)
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op_pi, 0, abstime);
else
{
struct timespec ts32, *pts32 = NULL;
if (abstime != NULL)
{
ts32 = valid_timespec64_to_timespec (*abstime);
pts32 = &ts32;
}
err = INTERNAL_SYSCALL_CALL (futex, futex_word, op_pi, 0, pts32);
}
# endif /* __ASSUME_TIME64_SYSCALLS */
/* FUTEX_LOCK_PI2 is not available on this kernel. */
if (err == -ENOSYS)
err = -EINVAL;
#endif /* __ASSUME_FUTEX_LOCK_PI2 */
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
case -ESRCH:
case -EDEADLK:
case -EINVAL: /* This indicates either state corruption or that the kernel
found a waiter on futex address which is waiting via
FUTEX_WAIT or FUTEX_WAIT_BITSET. This is reported on
some futex_lock_pi usage (pthread_mutex_timedlock for
instance). */
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}

3
nptl/pthread_mutex_lock.c
View File

@ -421,7 +421,8 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex)
int private = (robust
? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
: PTHREAD_MUTEX_PSHARED (mutex));
int e = futex_lock_pi64 (&mutex->__data.__lock, NULL, private);
int e = __futex_lock_pi64 (&mutex->__data.__lock, 0 /* ununsed */,
NULL, private);
if (e == ESRCH || e == EDEADLK)
{
assert (e != EDEADLK

3
nptl/pthread_mutex_timedlock.c
View File

@ -369,7 +369,8 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
int private = (robust
? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
: PTHREAD_MUTEX_PSHARED (mutex));
int e = futex_lock_pi64 (&mutex->__data.__lock, abstime, private);
int e = __futex_lock_pi64 (&mutex->__data.__lock, clockid, abstime,
private);
if (e == ETIMEDOUT)
return ETIMEDOUT;
else if (e == ESRCH || e == EDEADLK)

58
sysdeps/nptl/futex-internal.h
View File

@ -236,8 +236,8 @@ futex_wake (unsigned int* futex_word, int processes_to_wake, int private)
are done in descending priority order.
The ABSTIME arguments provides an absolute timeout (measured against the
CLOCK_REALTIME clock). If TIMEOUT is NULL, the operation will block
indefinitely.
CLOCK_REALTIME or CLOCK_MONOTONIC clock). If TIMEOUT is NULL, the operation
will block indefinitely.
Returns:
@ -250,58 +250,8 @@ futex_wake (unsigned int* futex_word, int processes_to_wake, int private)
futex.
- ETIMEDOUT if the ABSTIME expires.
*/
static __always_inline int
futex_lock_pi64 (int *futex_word, const struct __timespec64 *abstime,
int private)
{
int err;
#ifdef __ASSUME_TIME64_SYSCALLS
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word,
__lll_private_flag (FUTEX_LOCK_PI, private), 0,
abstime);
#else
bool need_time64 = abstime != NULL && !in_time_t_range (abstime->tv_sec);
if (need_time64)
{
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word,
__lll_private_flag (FUTEX_LOCK_PI, private),
0, abstime);
if (err == -ENOSYS)
err = -EOVERFLOW;
}
else
{
struct timespec ts32;
if (abstime != NULL)
ts32 = valid_timespec64_to_timespec (*abstime);
err = INTERNAL_SYSCALL_CALL (futex, futex_word, __lll_private_flag
(FUTEX_LOCK_PI, private), 0,
abstime != NULL ? &ts32 : NULL);
}
#endif
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
case -ESRCH:
case -EDEADLK:
case -EINVAL: /* This indicates either state corruption or that the kernel
found a waiter on futex address which is waiting via
FUTEX_WAIT or FUTEX_WAIT_BITSET. This is reported on
some futex_lock_pi usage (pthread_mutex_timedlock for
instance). */
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
int __futex_lock_pi64 (int *futex_word, clockid_t clockid,
const struct __timespec64 *abstime, int private);
/* Wakes the top priority waiter that called a futex_lock_pi operation on
the futex.

1
sysdeps/nptl/lowlevellock-futex.h
View File

@ -38,6 +38,7 @@
#define FUTEX_WAKE_BITSET 10
#define FUTEX_WAIT_REQUEUE_PI 11
#define FUTEX_CMP_REQUEUE_PI 12
#define FUTEX_LOCK_PI2 13
#define FUTEX_PRIVATE_FLAG 128
#define FUTEX_CLOCK_REALTIME 256