From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Florian Weimer <fweimer@redhat.com>,
Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>,
Lukasz Majewski <lukma@denx.de>
Subject: Re: [PATCH 03/13] nptl: Remove clockwait_tid
Date: Mon, 14 Dec 2020 09:52:12 -0300 [thread overview]
Message-ID: <71325370-edb0-a7ca-4759-bfbaf8518168@linaro.org> (raw)
In-Reply-To: <87v9d4d1m3.fsf@oldenburg2.str.redhat.com>
On 14/12/2020 09:16, Florian Weimer wrote:
> * Adhemerval Zanella via Libc-alpha:
>
>> -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);
>
> This uses FUTEX_WAIT. But the replacement,
> __futex_abstimed_wait_common64, uses FUTEX_WAIT_BITSET. I do not think
> this is correct because the kernel will use FUTEX_WAKE internally for
> the pd->tid wakeup relied upon by pthread_join.
>
> This seems to cause pthread_join regressions on some kernel versions.
>
> We need to audit all callers of __futex_abstimed_wait64 if they are
> actually compatible with FUTEX_WAIT_BITSET.
I don't think it should matter, as Andreas has put FUTEX_WAIT is exactly
as FUTEX_WAIT_BITSET plus FUTEX_BITSET_MATCH_ANY. On a recent kernel:
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
u32, val3)
{
[...]
return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
}
long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
u32 __user *uaddr2, u32 val2, u32 val3)
{
[...]
case FUTEX_WAIT:
val3 = FUTEX_BITSET_MATCH_ANY;
fallthrough;
case FUTEX_WAIT_BITSET:
return futex_wait(uaddr, flags, val, timeout, val3);
[...]
next prev parent reply other threads:[~2020-12-14 12:52 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 ` [PATCH 03/13] nptl: Remove clockwait_tid Adhemerval Zanella
2020-11-24 18:13 ` 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 [this message]
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=71325370-edb0-a7ca-4759-bfbaf8518168@linaro.org \
--to=adhemerval.zanella@linaro.org \
--cc=fweimer@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=lukma@denx.de \
--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).