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nptl: Replace __futex_clocklock_wait64 with __futex_abstimed_wait64

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For non null timeouts, the __futex_clocklock_wait64 creates an a
relative timeout by subtracting the current time from the input
argument.  The same behavior can be obtained with FUTEX_WAIT_BITSET
without the need to calculate the relative timeout.  Besides consolidate
the code it also avoid the possible relative timeout issues [1].

The __futex_abstimed_wait64 needs also to return EINVAL syscall
errors.

Checked on x86_64-linux-gnu and i686-linux-gnu.

[1] https://sourceware.org/pipermail/libc-alpha/2020-November/119881.html

Reviewed-by: Lukasz Majewski <lukma@denx.de>
This commit is contained in:
Adhemerval Zanella 2020-11-21 17:39:44 -03:00
parent a52665818a
commit a3e7aead03
3 changed files with 5 additions and 63 deletions
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4
nptl/pthread_mutex_timedlock.c
View File

@ -391,8 +391,8 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
/* Delay the thread until the timeout is reached. Then return
ETIMEDOUT. */
do
e = __futex_clocklock_wait64 (&(int){0}, 0, clockid, abstime,
private);
e = __futex_abstimed_wait64 (&(unsigned int){0}, 0, clockid,
abstime, private);
while (e != ETIMEDOUT);
return ETIMEDOUT;
}

57
sysdeps/nptl/futex-internal.c
View File

@ -90,15 +90,13 @@ __futex_abstimed_wait_common64 (unsigned int* futex_word,
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
case -EINVAL:
case -EOVERFLOW: /* Passed absolute timeout uses 64 bit time_t type, but
underlying kernel does not support 64 bit time_t futex
syscalls. */
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. 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:
@ -124,56 +122,3 @@ __futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
return __futex_abstimed_wait_common64 (futex_word, expected, clockid,
abstime, private, true);
}
int
__futex_clocklock_wait64 (int *futex, int val, clockid_t clockid,
const struct __timespec64 *abstime, int private)
{
struct __timespec64 ts, *tsp = NULL;
if (abstime != NULL)
{
/* Reject invalid timeouts. */
if (! valid_nanoseconds (abstime->tv_nsec))
return EINVAL;
/* Get the current time. This can only fail if clockid is not valid. */
if (__glibc_unlikely (__clock_gettime64 (clockid, &ts) != 0))
return EINVAL;
/* Compute relative timeout. */
ts.tv_sec = abstime->tv_sec - ts.tv_sec;
ts.tv_nsec = abstime->tv_nsec - ts.tv_nsec;
if (ts.tv_nsec < 0)
{
ts.tv_nsec += 1000000000;
--ts.tv_sec;
}
if (ts.tv_sec < 0)
return ETIMEDOUT;
tsp = &ts;
}
int err = INTERNAL_SYSCALL_CALL (futex_time64, futex,
__lll_private_flag (FUTEX_WAIT, private),
val, tsp);
#ifndef __ASSUME_TIME64_SYSCALLS
if (err == -ENOSYS)
{
if (tsp != NULL && ! in_time_t_range (tsp->tv_sec))
return EOVERFLOW;
struct timespec ts32;
if (tsp != NULL)
ts32 = valid_timespec64_to_timespec (*tsp);
err = INTERNAL_SYSCALL_CALL (futex, futex,
__lll_private_flag (FUTEX_WAIT, private),
val, tsp != NULL ? &ts32 : NULL);
}
#endif
return -err;
}

7
sysdeps/nptl/futex-internal.h
View File

@ -413,10 +413,6 @@ __futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
const struct __timespec64* abstime,
int private) attribute_hidden;
int
__futex_clocklock_wait64 (int *futex, int val, clockid_t clockid,
const struct __timespec64 *abstime,
int private) attribute_hidden;
static __always_inline int
__futex_clocklock64 (int *futex, clockid_t clockid,
@ -428,7 +424,8 @@ __futex_clocklock64 (int *futex, clockid_t clockid,
{
while (atomic_exchange_acq (futex, 2) != 0)
{
err = __futex_clocklock_wait64 (futex, 2, clockid, abstime, private);
err = __futex_abstimed_wait64 ((unsigned int *) futex, 2, clockid,
abstime, private);
if (err == EINVAL || err == ETIMEDOUT || err == EOVERFLOW)
break;
}