From: Peter Zijlstra <peterz@infradead.org>
To: David Laight <David.Laight@aculab.com>
Cc: 'Waiman Long' <longman@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Jann Horn <jannh@google.com>,
Vasiliy Kulikov <segoon@openwall.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Bernd Edlinger <bernd.edlinger@hotmail.de>,
Oleg Nesterov <oleg@redhat.com>,
Christopher Yeoh <cyeoh@au1.ibm.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Sargun Dhillon <sargun@sargun.me>,
Christian Brauner <christian.brauner@ubuntu.com>,
Arnd Bergmann <arnd@arndb.de>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: [PATCH 2/3] rwsem: Implement down_read_interruptible
Date: Tue, 8 Dec 2020 13:32:04 +0100 [thread overview]
Message-ID: <20201208123204.GW2414@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <71db845efc7d44b5a7d23b0e55b3a496@AcuMS.aculab.com>
On Tue, Dec 08, 2020 at 09:12:36AM +0000, David Laight wrote:
> From: Waiman Long
> > Sent: 07 December 2020 19:02
> ...
> > > How much more difficult would it be to also add a timeout option?
> > > I looked at adding one to the mutex code - and fell into a big pile
> > > of replicated code.
> > >
> > > ISTM that one the initial locked exchange (and spin) fails a few
> > > extra instructions when heading for the sleep don't really matter
> > >
> > Actually, I had tried that before. See
> >
> > https://lore.kernel.org/lkml/20190911150537.19527-1-longman@redhat.com/
> >
> > That is for rwsem, but the same can be done for mutex. However, Peter
> > didn't seem to like the idea of a timeout parameter. Anyway, it is
> > certainly doable if there is a good use case for it.
>
> 'Unfortunately' my use-case if for an out-of-tree driver.
>
> The problem I was solving is a status call blocking because
> some other code is 'stuck' (probably an oops) with a mutex held.
Working around oopses is not a sane use-case. If you oops, you get to
keep all the pieces.
next prev parent reply other threads:[~2020-12-08 12:33 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 20:09 [PATCH 0/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-03 20:10 ` [PATCH 1/3] rwsem: Implement down_read_killable_nested Eric W. Biederman
2020-12-04 1:58 ` Waiman Long
2020-12-09 18:38 ` [tip: locking/core] " tip-bot2 for Eric W. Biederman
2020-12-03 20:11 ` [PATCH 2/3] rwsem: Implement down_read_interruptible Eric W. Biederman
2020-12-04 1:59 ` Waiman Long
2020-12-07 9:02 ` Peter Zijlstra
2020-12-07 15:33 ` Waiman Long
2020-12-07 16:58 ` David Laight
2020-12-07 19:02 ` Waiman Long
2020-12-08 9:12 ` David Laight
2020-12-08 12:32 ` Peter Zijlstra [this message]
2020-12-08 13:13 ` David Laight
2020-12-08 15:34 ` Waiman Long
2020-12-08 16:23 ` David Laight
2020-12-07 15:56 ` Eric W. Biederman
2020-12-08 14:52 ` Peter Zijlstra
2020-12-08 18:27 ` Eric W. Biederman
2020-12-09 18:36 ` Peter Zijlstra
2020-12-10 19:33 ` Eric W. Biederman
2020-12-11 8:16 ` Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] locking/rwsem: Fold __down_{read,write}*() tip-bot2 for Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] locking/rwsem: Introduce rwsem_write_trylock() tip-bot2 for Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] locking/rwsem: Better collate rwsem_read_trylock() tip-bot2 for Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] rwsem: Implement down_read_interruptible tip-bot2 for Eric W. Biederman
2020-12-03 20:12 ` [PATCH 3/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-04 16:08 ` Bernd Edlinger
2020-12-04 17:21 ` Linus Torvalds
2020-12-04 19:34 ` Eric W. Biederman
2020-12-04 20:10 ` Linus Torvalds
2020-12-04 20:30 ` Bernd Edlinger
2020-12-04 20:48 ` Linus Torvalds
2020-12-04 21:48 ` Davidlohr Bueso
2020-12-05 18:05 ` Eric W. Biederman
2020-12-07 9:15 ` Peter Zijlstra
2020-12-07 9:09 ` Peter Zijlstra
2020-12-07 18:40 ` Linus Torvalds
2020-12-08 8:34 ` [PATCH] perf: Break deadlock involving exec_update_mutex Peter Zijlstra
2020-12-08 18:37 ` Linus Torvalds
2020-12-10 18:38 ` Davidlohr Bueso
2020-12-10 19:40 ` Eric W. Biederman
2020-12-05 17:43 ` [PATCH 3/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-04 17:39 ` Eric W. Biederman
2020-12-03 22:42 ` [PATCH 0/3] " Linus Torvalds
2020-12-04 1:56 ` Waiman Long
2020-12-04 4:54 ` Davidlohr Bueso
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