From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>,
Lukasz Majewski <lukma@denx.de>,
Florian Weimer <fweimer@redhat.com>,
Carlos O'Donell <carlos@redhat.com>,
"Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Ingo Molnar <mingo@kernel.org>,
Kurt Kanzenbach <kurt@linutronix.de>,
Darren Hart <dvhart@infradead.org>,
Andrei Vagin <avagin@gmail.com>
Subject: [patch 5/6] futex: Prepare futex_lock_pi() for runtime clock selection
Date: Thu, 22 Apr 2021 21:44:22 +0200 [thread overview]
Message-ID: <20210422194705.338657741@linutronix.de> (raw)
In-Reply-To: 20210422194417.866740847@linutronix.de
futex_lock_pi() is the only futex operation which cannot select the clock
for timeouts (CLOCK_MONOTONIC/CLOCK_REALTIME). That's inconsistent and
there is no particular reason why this cannot be supported.
This was overlooked when CLOCK_REALTIME_FLAG was introduced and
unfortunately not reported when the inconsistency was discovered in glibc.
Prepare the function and enforce the CLOCK_REALTIME_FLAG on FUTEX_LOCK_PI
so that a new FUTEX_LOCK_PI2 can implement it correctly.
Reported-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/futex.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2786,7 +2786,7 @@ static int futex_lock_pi(u32 __user *uad
if (refill_pi_state_cache())
return -ENOMEM;
- to = futex_setup_timer(time, &timeout, FLAGS_CLOCKRT, 0);
+ to = futex_setup_timer(time, &timeout, flags, 0);
retry:
ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key, FUTEX_WRITE);
@@ -3711,7 +3711,7 @@ long do_futex(u32 __user *uaddr, int op,
if (op & FUTEX_CLOCK_REALTIME) {
flags |= FLAGS_CLOCKRT;
- if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI)
+ if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI)
return -ENOSYS;
}
@@ -3743,6 +3743,7 @@ long do_futex(u32 __user *uaddr, int op,
case FUTEX_WAKE_OP:
return futex_wake_op(uaddr, flags, uaddr2, val, val2, val3);
case FUTEX_LOCK_PI:
+ flags |= FLAGS_CLOCKRT;
return futex_lock_pi(uaddr, flags, timeout, 0);
case FUTEX_UNLOCK_PI:
return futex_unlock_pi(uaddr, flags);
next prev parent reply other threads:[~2021-04-22 20:29 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 19:44 [patch 0/6] futex: Bugfixes and FUTEX_LOCK_PI2 Thomas Gleixner
2021-04-22 19:44 ` [patch 1/6] Revert 337f13046ff0 ("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op") Thomas Gleixner
2021-05-06 18:14 ` [tip: locking/urgent] " tip-bot2 for Thomas Gleixner
2021-04-22 19:44 ` [patch 2/6] futex: Do not apply time namespace adjustment on FUTEX_LOCK_PI Thomas Gleixner
2021-05-06 18:14 ` [tip: locking/urgent] " tip-bot2 for Thomas Gleixner
2021-04-22 19:44 ` [patch 3/6] futex: Get rid of the val2 conditional dance Thomas Gleixner
2021-04-23 21:40 ` André Almeida
2021-04-23 22:34 ` Thomas Gleixner
2021-04-23 23:21 ` André Almeida
2021-05-06 18:20 ` [tip: locking/urgent] " tip-bot2 for Thomas Gleixner
2021-04-22 19:44 ` [patch 4/6] futex: Make syscall entry points less convoluted Thomas Gleixner
2021-05-06 18:20 ` [tip: locking/urgent] " tip-bot2 for Thomas Gleixner
2021-04-22 19:44 ` Thomas Gleixner [this message]
2021-04-23 9:34 ` [patch 5/6] futex: Prepare futex_lock_pi() for runtime clock selection Lukasz Majewski
2021-04-23 10:08 ` Thomas Gleixner
2021-06-23 8:19 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-04-22 19:44 ` [patch 6/6] futex: Provide FUTEX_LOCK_PI2 to support " Thomas Gleixner
2021-04-23 22:20 ` André Almeida
2021-04-23 22:36 ` Thomas Gleixner
2021-06-23 8:19 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-05-05 12:59 ` [patch 0/6] futex: Bugfixes and FUTEX_LOCK_PI2 Peter Zijlstra
2021-05-05 13:51 ` Kurt Kanzenbach
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=20210422194705.338657741@linutronix.de \
--to=tglx@linutronix.de \
--cc=adhemerval.zanella@linaro.org \
--cc=avagin@gmail.com \
--cc=carlos@redhat.com \
--cc=dave@stgolabs.net \
--cc=dvhart@infradead.org \
--cc=fweimer@redhat.com \
--cc=kurt@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=lukma@denx.de \
--cc=mingo@kernel.org \
--cc=mtk.manpages@gmail.com \
--cc=peterz@infradead.org \
/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 NNTP newsgroup(s).