From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Cc: Mike Crowe <mac@mcrowe.com>, Michael Kerrisk <mtk.manpages@gmail.com>
Subject: [PATCH 03/13] nptl: Remove clockwait_tid
Date: Mon, 23 Nov 2020 16:52:46 -0300 [thread overview]
Message-ID: <20201123195256.3336217-3-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20201123195256.3336217-1-adhemerval.zanella@linaro.org>
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.
---
nptl/pthread_join_common.c | 70 ++++++-----------------------------
sysdeps/nptl/futex-internal.h | 49 ------------------------
2 files changed, 12 insertions(+), 107 deletions(-)
diff --git a/nptl/pthread_join_common.c b/nptl/pthread_join_common.c
index 67d8e2b780..8a95c58ff3 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 +88,18 @@ __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)
+ {
+ 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 96d1318091..d5f13d15fb 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. */
--
2.25.1
next prev parent reply other threads:[~2020-11-23 19:53 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-23 19:52 [PATCH 01/13] linux: Remove unused internal futex functions Adhemerval Zanella
2020-11-23 19:52 ` [PATCH 02/13] nptl: Remove futex_wait_cancelable Adhemerval Zanella
2020-11-24 18:01 ` Lukasz Majewski
2020-11-23 19:52 ` Adhemerval Zanella [this message]
2020-11-24 18:13 ` [PATCH 03/13] nptl: Remove clockwait_tid Lukasz Majewski
2020-12-14 12:16 ` Florian Weimer
2020-12-14 12:47 ` Andreas Schwab
2020-12-14 13:11 ` Florian Weimer
2020-12-14 14:02 ` Florian Weimer
2020-12-14 12:52 ` Adhemerval Zanella
2020-11-23 19:52 ` [PATCH 04/13] linux: Extend __futex_abstimed_wait_cancelable64 comment Adhemerval Zanella
2020-11-24 18:16 ` Lukasz Majewski
2020-11-23 19:52 ` [PATCH 05/13] linux: nptl: Consolidate __futex_abstimed_wait_{cancelable}64 Adhemerval Zanella
2020-11-24 18:19 ` Lukasz Majewski
2020-11-23 19:52 ` [PATCH 06/13] linux: nptl: Remove _futex_clock_wait_bitset64 Adhemerval Zanella
2020-11-24 18:26 ` Lukasz Majewski
2020-11-23 19:52 ` [PATCH 07/13] linux: nptl: Replace __futex_clocklock_wait64 with __futex_abstimed_wait64 Adhemerval Zanella
2020-11-24 21:28 ` Lukasz Majewski
2020-11-23 19:52 ` [PATCH 08/13] linux: nptl: Replace lll_timedwait " Adhemerval Zanella
2020-11-24 21:29 ` Lukasz Majewski
2020-11-23 19:52 ` [PATCH 09/13] linux: nptl: Replace lll_futex_{timed_}wait by futex-internal.h Adhemerval Zanella
2020-11-24 21:35 ` Lukasz Majewski
2020-11-25 15:32 ` Mike Crowe
2020-11-25 15:40 ` Adhemerval Zanella
2020-11-25 15:46 ` Mike Crowe
2020-11-25 17:19 ` Adhemerval Zanella
2020-11-25 17:37 ` Mike Crowe
2020-11-25 17:56 ` Adhemerval Zanella
2020-11-23 19:52 ` [PATCH 10/13] linux: nptl: Replace lll_futex_supported_clockid with futex-internal.h Adhemerval Zanella
2020-11-24 21:36 ` Lukasz Majewski
2020-11-23 19:52 ` [PATCH 11/13] nptl: Replace lll_futex_wake " Adhemerval Zanella
2020-11-24 21:38 ` Lukasz Majewski
2020-11-23 19:52 ` [PATCH v2 12/13] nptl: Return EINVAL for pthread_mutex_clocklock/PI with CLOCK_MONOTONIC [BZ #26801] Adhemerval Zanella
2020-11-24 21:43 ` Lukasz Majewski
2020-11-24 21:49 ` Lukasz Majewski
2020-11-27 17:39 ` Adhemerval Zanella
2020-11-23 19:52 ` [PATCH 13/13] linux: Return EINVAL for invalid clock for pthread_clockjoin_np Adhemerval Zanella
2020-11-24 21:48 ` Lukasz Majewski
2020-11-24 22:58 ` Lukasz Majewski
2020-11-24 17:51 ` [PATCH 01/13] linux: Remove unused internal futex functions Lukasz Majewski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201123195256.3336217-3-adhemerval.zanella@linaro.org \
--to=adhemerval.zanella@linaro.org \
--cc=libc-alpha@sourceware.org \
--cc=mac@mcrowe.com \
--cc=mtk.manpages@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).