From mboxrd@z Thu Jan  1 00:00:00 1970
From: p.ittershagen@googlemail.com (Philipp Ittershagen)
Date: Wed, 25 Apr 2012 00:06:26 +0200
Subject: side effects of calling interruptible_sleep_on_timeout()
In-Reply-To: <CACsJYqoJBbnV5C8BmmO11k=hEaNiF-D=Yso2RyaPMM86Htw2KA@mail.gmail.com>
References: <CACsJYqoJBbnV5C8BmmO11k=hEaNiF-D=Yso2RyaPMM86Htw2KA@mail.gmail.com>
Message-ID: <20120424220626.GA6655@peter>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hi Devendra,

On Tue, Apr 24, 2012 at 03:24:23PM +0530, devendra rawat wrote:
>    Hi,
>    A switch driver is causing soft lockup on Montavista Linux Kernel
>    2.6.10 system.
>    While browsing through the code of the driver. I came across a snippet
>    where after disabling the interrupts
>    a call is made to interruptible_sleep_on_timeout().
>    The code snippet is like
>    cli();
>    init_waitqueue_head(&queue);
>            interruptible_sleep_on_timeout(&queue, USEC_TO_JIFFIES(usec));
>            thread_check_signals();
>    sti();
>    I need to know the side effect of this sort of code, can it be
>    responsible for the softlockup of the system ? Its a PowerPC based
>    system.

you cannot call sleep functions after disabling interrupts, because no
interrupt will arrive for the scheduler to see the timeout and resume your
task.


Greetings,

  Philipp