Re: [PATCH][RFC] preempt_count corruption across H_CEDE call with CONFIG_PREEMPT on pseries
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2010-07-23 05:13:31
On Fri, 2010-07-23 at 10:38 +0530, Vaidyanathan Srinivasan wrote:
Yes. extended_cede_processor() will return with interrupts enabled in the cpu. (This is done by the hypervisor). Under normal cases we cannot be interrupted because no IO interrupts are routed to us after xics_teardown_cpu() and since the CPU is out of the map, nobody will send us IPIs.
What about decrementer ?
Though H_CEDE will return with interrupts enabled, it is unlikely that an interrupt can be delivered in this context.
Well, if interrupts are soft-disabled, even if one occurs, we will just mask and return, so that at least should be ok. Cheers, Ben.