On 04/25/2012 03:36 AM, Philipp Ittershagen wrote:
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.
Yes, that's right. Also, in general, sleeping inside atomic sections (eg., sections with interrupts disabled or preempt disabled) is wrong. There is a config option in the kernel that you can use to enable sleep-inside-atomic-section-checking (CONFIG_DEBUG_ATOMIC_SLEEP I believe), which can help you pin-point such bugs easily. Regards, Srivatsa S. Bhat