linux-kernel - Re: wait_even_interruptible_timeout(), signal, spin

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Date:	Sun, 6 Jun 2010 09:25:43 -0500
From:	Shirish Pargaonkar <shirishpargaonkar@...il.com>
To:	maciej.rutecki@...il.com
Cc:	linux-kernel@...r.kernel.org,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: wait_even_interruptible_timeout(), signal, spin_lock() = system 
	hang

On Sun, Jun 6, 2010 at 3:00 AM, Maciej Rutecki <maciej.rutecki@...il.com> wrote:
> I created a Bugzilla entry at
> https://bugzilla.kernel.org/show_bug.cgi?id=16139
> for your bug report, please add your address to the CC list in there, thanks!
>
> On piątek, 28 maja 2010 o 18:44:46 Shirish Pargaonkar wrote:
>> After this sequence of calls, system hangs (smp, x86 box based with
>> .34 kernel), can ping only.
>> I have not been able to break in with Alt Sysrq t, working on that
>>
>>         rc = wait_event_interruptible_timeout(ses->server->response_q,
>>                         (midQ->midState != MID_REQUEST_SUBMITTED),
>>  timeout); if (rc < 0) {
>>                 cFYI(1, ("command 0x%x interrupted", midQ->command));
>>                 return -1;
>>         }
>>
>> and when function that invoking function after coming out with ERESTARTSYS
>> (I kill the command with Ctrl C) calls
>>  spin_lock(&GlobalMid_Lock);
>>
>> system hangs.  If I sleep before return -1 (e.g. msleep(1), no hang)
>>
>> I do not have to use wait_event_interruptible_timeout and no such problems
>>  with wait_event_timeout, it is only when signal/interrupt is involved, I
>>  run into this problem
>>
>> Any pointers/ideas what could be happening, would be really really
>>  appreciated.
>>
>> Regards,
>>
>> Shirish
>> --
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>
> --
> Maciej Rutecki
> http://www.maciek.unixy.pl
>

Thanks. Shaggy told me what I think is happening should not be for
following reasons.

"The process doesn't receive the signal in the
kernel unless it specifically checks for it, or it exits a system call.
There shouldn't be a spinlock held in either situation.
"

I will update the bug as well.

Regards,

Shirish
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