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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2020-11-23 15:28:57 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2020-11-25 10:40:59 -0300
commit9e92278ffad441daf588ff1ff5bd8094aa33fbfd (patch)
tree82fde8252c3b0bd9927a7da6f81e241d07353984
parent2e39f65b5ef11647beb4980c4244bac8af192c14 (diff)
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nptl: Remove clockwait_tid
It can be replaced with a __futex_abstimed_wait_cancelable64 call, with the advantage that there is no need to further clock adjustments to create a absolute timeout. It allows to remove the now ununsed futex_timed_wait_cancel64 internal function. Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Lukasz Majewski <lukma@denx.de>
-rw-r--r--nptl/pthread_join_common.c76
-rw-r--r--sysdeps/nptl/futex-internal.h49
2 files changed, 18 insertions, 107 deletions
diff --git a/nptl/pthread_join_common.c b/nptl/pthread_join_common.c
index 67d8e2b..4293b07 100644
--- a/nptl/pthread_join_common.c
+++ b/nptl/pthread_join_common.c
@@ -32,55 +32,6 @@ cleanup (void *arg)
atomic_compare_exchange_weak_acquire (&arg, &self, NULL);
}
-/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
- wake-up when the clone terminates. The memory location contains the
- thread ID while the clone is running and is reset to zero by the kernel
- afterwards. The kernel up to version 3.16.3 does not use the private futex
- operations for futex wake-up when the clone terminates. */
-static int
-clockwait_tid (pid_t *tidp, clockid_t clockid,
- const struct __timespec64 *abstime)
-{
- pid_t tid;
- int ret;
-
- if (! valid_nanoseconds (abstime->tv_nsec))
- return EINVAL;
-
- /* Repeat until thread terminated. */
- while ((tid = *tidp) != 0)
- {
- struct __timespec64 rt;
-
- /* Get the current time. This can only fail if clockid is
- invalid. */
- if (__glibc_unlikely (__clock_gettime64 (clockid, &rt)))
- return EINVAL;
-
- /* Compute relative timeout. */
- rt.tv_sec = abstime->tv_sec - rt.tv_sec;
- rt.tv_nsec = abstime->tv_nsec - rt.tv_nsec;
- if (rt.tv_nsec < 0)
- {
- rt.tv_nsec += 1000000000;
- --rt.tv_sec;
- }
-
- /* Already timed out? */
- if (rt.tv_sec < 0)
- return ETIMEDOUT;
-
- /* If *tidp == tid, wait until thread terminates or the wait times out.
- The kernel up to version 3.16.3 does not use the private futex
- operations for futex wake-up when the clone terminates. */
- ret = futex_timed_wait_cancel64 (tidp, tid, &rt, LLL_SHARED);
- if (ret == -ETIMEDOUT || ret == -EOVERFLOW)
- return -ret;
- }
-
- return 0;
-}
-
int
__pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
clockid_t clockid,
@@ -137,15 +88,24 @@ __pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
un-wait-ed for again. */
pthread_cleanup_push (cleanup, &pd->joinid);
- if (abstime != NULL)
- result = clockwait_tid (&pd->tid, clockid, abstime);
- else
- {
- pid_t tid;
- /* We need acquire MO here so that we synchronize with the
- kernel's store to 0 when the clone terminates. (see above) */
- while ((tid = atomic_load_acquire (&pd->tid)) != 0)
- lll_futex_wait_cancel (&pd->tid, tid, LLL_SHARED);
+ /* We need acquire MO here so that we synchronize with the
+ kernel's store to 0 when the clone terminates. (see above) */
+ pid_t tid;
+ while ((tid = atomic_load_acquire (&pd->tid)) != 0)
+ {
+ /* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via
+ futex wake-up when the clone terminates. The memory location
+ contains the thread ID while the clone is running and is reset to
+ zero by the kernel afterwards. The kernel up to version 3.16.3
+ does not use the private futex operations for futex wake-up when
+ the clone terminates. */
+ int ret = __futex_abstimed_wait_cancelable64 (
+ (unsigned int *) &pd->tid, tid, clockid, abstime, LLL_SHARED);
+ if (ret == ETIMEDOUT || ret == EOVERFLOW)
+ {
+ result = ret;
+ break;
+ }
}
pthread_cleanup_pop (0);
diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
index 96d1318..d5f13d1 100644
--- a/sysdeps/nptl/futex-internal.h
+++ b/sysdeps/nptl/futex-internal.h
@@ -390,55 +390,6 @@ futex_unlock_pi (unsigned int *futex_word, int private)
}
}
-static __always_inline int
-futex_timed_wait_cancel64 (pid_t *tidp, pid_t tid,
- const struct __timespec64 *timeout, int private)
-{
- int err = INTERNAL_SYSCALL_CANCEL (futex_time64, tidp,
- __lll_private_flag (FUTEX_WAIT, private),
- tid, timeout);
-#ifndef __ASSUME_TIME64_SYSCALLS
- if (err == -ENOSYS)
- {
- if (in_time_t_range (timeout->tv_sec))
- {
- struct timespec ts32 = valid_timespec64_to_timespec (*timeout);
-
- err = INTERNAL_SYSCALL_CANCEL (futex, tidp,
- __lll_private_flag (FUTEX_WAIT,
- private),
- tid, &ts32);
- }
- else
- err = -EOVERFLOW;
- }
-#endif
- switch (err)
- {
- case 0:
- case -EAGAIN:
- case -EINTR:
- case -ETIMEDOUT:
- case -EDEADLK:
- case -ENOSYS:
- case -EOVERFLOW: /* Passed absolute timeout uses 64 bit time_t type, but
- underlying kernel does not support 64 bit time_t futex
- syscalls. */
- case -EPERM: /* The caller is not allowed to attach itself to the futex.
- Used to check if PI futexes are supported by the
- kernel. */
- return -err;
-
- 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 -EFAULT: /* Must have been caused by a glibc or application bug. */
- /* No other errors are documented at this time. */
- default:
- futex_fatal_error ();
- }
-}
-
/* The futex_abstimed_wait_cancelable64 has been moved to a separate file
to avoid problems with exhausting available registers on some architectures
- e.g. on m68k architecture. */