Re: [Xen-devel] [PATCH for v4.9] livepatch: Wrong usage of spinlock on debug console.

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 06/09/2017 10:16 AM, Konrad Rzeszutek Wilk wrote:
> If we have a large amount of livepatches and want to print them
> on the console using 'xl debug-keys x' we eventually hit
> the preemption check:
>
>   if ( i && !(i % 64) )
>   {
>       spin_unlock(&payload_lock);
>       process_pending_softirqs();
>       if ( spin_trylock(&payload_lock) )
>               return
>
> <facepalm> The effect is that we have just effectively
> taken the lock and returned without unlocking!
>
> CC: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> CC: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>


Reviewed-and-tested-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>



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