Re: [PATCH] NTP: remove clock_was_set() call to prevent deadlock

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



* Thomas Gleixner <[email protected]> wrote:

> The clock_was_set() call in seconds_overflow() which happens only when 
> leap seconds are inserted / deleted is wrong in two aspects:
> 
> 1. it results in a call to on_each_cpu() with interrupts disabled
> 2. it is potential deadlock source vs. call_lock in smp_call_function()
> 
> The only possible side effect of the removal might be, that an 
> absolute CLOCK_REALTIME timer fires 1 second too late, in the rare 
> case of leap second deletion and an absolute CLOCK_REALTIME timer 
> which expires in the affected time frame. It will never fire too 
> early.
> 
> This was probably observed by the reporter of a June 30th -> July 1st 
> hang: http://lkml.org/lkml/2007/7/3/
> 
> A similar problem was observed by Dave Jones, who provided a screen 
> shot with a lockdep back trace, which allowed to analyse the problem.
> 
> Signed-off-by: Thomas Gleixner <[email protected]>

looks good to me.

Acked-by: Ingo Molnar <[email protected]>

	Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux