On Mon, 25 Jan 2010 22:26:39 -0600 Jason Wessel <jason.wes...@windriver.com> wrote:
> This is a regression fix against: 0f8e8ef7c204988246da5a42d576b7fa5277a8e4 > > Spin locks were added to the clocksource_resume_watchdog() which cause > the kernel debugger to deadlock on an SMP system frequently. > > The kernel debugger can try for the lock, but if it fails it should > continue to touch the clocksource watchdog anyway, else it will trip > if the general kernel execution has been paused for too long. > > This introduces an possible race condition where the kernel debugger > might not process the list correctly if a clocksource is being added > or removed at the time of this call. This race is sufficiently rare vs > having the kernel debugger hang the kernel > > CC: Thomas Gleixner <t...@linutronix.de> > CC: Martin Schwidefsky <schwidef...@de.ibm.com> > CC: John Stultz <johns...@us.ibm.com> > CC: Andrew Morton <a...@linux-foundation.org> > CC: Magnus Damm <d...@igel.co.jp> > Signed-off-by: Jason Wessel <jason.wes...@windriver.com> The first question I would ask is why does the kernel deadlock? Can we have a backchain of a deadlock please? Hmm, there are all kinds of races if the watchdog code gets interrupted by the kernel debugger. Wouldn't it be better to just disable the watchdog while the kernel debugger is active? -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ Kgdb-bugreport mailing list Kgdb-bugreport@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kgdb-bugreport
