From: Peter Zijlstra <peterz@infradead.org> To: chas williams - CONTRACTOR <chas@cmf.nrl.navy.mil> Cc: Fengguang Wu <fengguang.wu@intel.com>, netdev@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>, lkp@01.org, linux-atm-general@lists.sourceforge.net Subject: Re: [setsockopt] WARNING: CPU: 0 PID: 1444 at kernel/sched/core.c:7088 __might_sleep+0x51/0x16f() Date: Thu, 7 Aug 2014 19:25:14 +0200 [thread overview] Message-ID: <20140807172514.GY9918@twins.programming.kicks-ass.net> (raw) In-Reply-To: <20140807125948.2b7f1472@thirdoffive.cmf.nrl.navy.mil> [-- Attachment #1: Type: text/plain, Size: 2093 bytes --] On Thu, Aug 07, 2014 at 12:59:48PM -0400, chas williams - CONTRACTOR wrote: > On Thu, 7 Aug 2014 17:17:41 +0200 > Peter Zijlstra <peterz@infradead.org> wrote: > > > Subject: atm: Fix blocking in wait loop > > > > One should not call blocking primitives inside a wait loop, since both > > require task_struct::state to sleep, so the inner will destroy the outer > > state. > > > > In this instance sigd_enq() will possible sleep for alloc_skb(), now if > > I understand the code right, we do not actually need to call sigd_enq() > > after the initial prepare_to_wait(), because we test the termination > > condition before schedule() anyhow. > > > > So we can simply move it up a bit and avoid the entire confusion. > > > > Signed-off-by: Peter Zijlstra <peterz@infradead.org> > > --- > > net/atm/svc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/atm/svc.c b/net/atm/svc.c > > index d8e5d0c2ebbc..445ac238b69b 100644 > > --- a/net/atm/svc.c > > +++ b/net/atm/svc.c > > @@ -297,8 +297,8 @@ static int svc_listen(struct socket *sock, int backlog) > > goto out; > > } > > set_bit(ATM_VF_WAITING, &vcc->flags); > > - prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE); > > sigd_enq(vcc, as_listen, NULL, NULL, &vcc->local); > > + prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE); > > while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) { > > schedule(); > > prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE); > > > This isn't the only place that we queue a message for the signalling > daemon after a prepare_to_wait() uninterruptibly so this patch would > be incomplete as is. I'm not sure I follow, this is the only place you do so while then going to sleep. All other sites don't sleep while they're enqueued on the waitqueue. > What bothers me is the TASK_UNINTERRUPTIBLE -- I don't have a good > reason why any of these should be sleeping uninterruptibly. That's a whole different story, there's tons of ugly in there, but its all ancient code. [-- Attachment #2: Type: application/pgp-signature, Size: 836 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: lkp@lists.01.org Subject: Re: [setsockopt] WARNING: CPU: 0 PID: 1444 at kernel/sched/core.c:7088 __might_sleep+0x51/0x16f() Date: Thu, 07 Aug 2014 19:25:14 +0200 [thread overview] Message-ID: <20140807172514.GY9918@twins.programming.kicks-ass.net> (raw) In-Reply-To: <20140807125948.2b7f1472@thirdoffive.cmf.nrl.navy.mil> [-- Attachment #1: Type: text/plain, Size: 2093 bytes --] On Thu, Aug 07, 2014 at 12:59:48PM -0400, chas williams - CONTRACTOR wrote: > On Thu, 7 Aug 2014 17:17:41 +0200 > Peter Zijlstra <peterz@infradead.org> wrote: > > > Subject: atm: Fix blocking in wait loop > > > > One should not call blocking primitives inside a wait loop, since both > > require task_struct::state to sleep, so the inner will destroy the outer > > state. > > > > In this instance sigd_enq() will possible sleep for alloc_skb(), now if > > I understand the code right, we do not actually need to call sigd_enq() > > after the initial prepare_to_wait(), because we test the termination > > condition before schedule() anyhow. > > > > So we can simply move it up a bit and avoid the entire confusion. > > > > Signed-off-by: Peter Zijlstra <peterz@infradead.org> > > --- > > net/atm/svc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/atm/svc.c b/net/atm/svc.c > > index d8e5d0c2ebbc..445ac238b69b 100644 > > --- a/net/atm/svc.c > > +++ b/net/atm/svc.c > > @@ -297,8 +297,8 @@ static int svc_listen(struct socket *sock, int backlog) > > goto out; > > } > > set_bit(ATM_VF_WAITING, &vcc->flags); > > - prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE); > > sigd_enq(vcc, as_listen, NULL, NULL, &vcc->local); > > + prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE); > > while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) { > > schedule(); > > prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE); > > > This isn't the only place that we queue a message for the signalling > daemon after a prepare_to_wait() uninterruptibly so this patch would > be incomplete as is. I'm not sure I follow, this is the only place you do so while then going to sleep. All other sites don't sleep while they're enqueued on the waitqueue. > What bothers me is the TASK_UNINTERRUPTIBLE -- I don't have a good > reason why any of these should be sleeping uninterruptibly. That's a whole different story, there's tons of ugly in there, but its all ancient code. [-- Attachment #2: attachment.sig --] [-- Type: application/pgp-signature, Size: 836 bytes --]
next prev parent reply other threads:[~2014-08-07 17:25 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-08-05 21:46 [setsockopt] WARNING: CPU: 0 PID: 1444 at kernel/sched/core.c:7088 __might_sleep+0x51/0x16f() Fengguang Wu 2014-08-05 21:46 ` Fengguang Wu 2014-08-05 21:54 ` Fengguang Wu 2014-08-05 21:54 ` Fengguang Wu 2014-08-06 13:52 ` Nick Krause 2014-08-07 15:17 ` Peter Zijlstra 2014-08-07 15:17 ` Peter Zijlstra 2014-08-07 16:59 ` chas williams - CONTRACTOR 2014-08-07 16:59 ` chas williams - CONTRACTOR 2014-08-07 17:25 ` Peter Zijlstra [this message] 2014-08-07 17:25 ` Peter Zijlstra 2014-08-07 17:29 ` Peter Zijlstra 2014-08-07 17:29 ` Peter Zijlstra 2014-08-12 12:12 ` [PATCH] atm/svc: Fix blocking in wait loop chas williams - CONTRACTOR 2014-08-12 12:12 ` chas williams - CONTRACTOR 2014-08-12 22:02 ` David Miller 2014-08-12 22:02 ` David Miller
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