Message-ID: <426EDE19.3030600@mvista.com>
Date: Tue, 26 Apr 2005 17:34:33 -0700
From: George Anzinger <george@mvista.com>
Reply-To: george@mvista.com
Organization: MontaVista Software
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To: dwalker@mvista.com
CC: ganzinger@mvista.com, Ingo Molnar <mingo@elte.hu>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: del_timer_sync needed for UP  RT systems.
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Daniel Walker wrote:
> On Tue, 2005-04-26 at 17:14, George Anzinger wrote:
> 
> 
>>The problem here is that the reference is to timr, a pointer to something which 
>>has been deleted.  The memory may well be used elsewhere by this time which will 
>>make the test of it_process wrong.  It also means we could mess with someone 
>>elses memory in the memset above.
> 
> 
> Bottom line, you can use sys_timer_delete() on a timer, and trigger the
> same timer your deleting .. Those operations should be serialized, which
> they currently aren't .. 

I agree.  The change to do this is to use the del_timer_sync() or the 
del_singleshot_timer() code.

It is possible and desirable to be able to delete a running timer.  We don't 
want to take it away from the timer call back routine, however, as that leads to 
"bad things".  That is why these two del_* routines were written.
> 
-- 
George Anzinger   george@mvista.com
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
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