Re: [PATCH 0/8] patchset focus on MIPS SMP woes

[Sergei Shtylyov]

Hello.

On 05/17/2012 08:13 PM, David Daney wrote:

> > From: Yong Zhang<yong.zhang@xxxxxxxxxxxxx>

> > Since commit 5fbd036b [sched: Cleanup cpu_active madness] and
> > commit 2baab4e9 [sched: Fix select_fallback_rq() vs cpu_active/cpu_online],
> > it's more safe to put notify_cpu_starting() and set_cpu_online() with
> > irq disabled, otherwise we will have a typical race condition which
> > above two commits try to resolve:

> > CPU1 CPU2
> > __cpu_up();
> > mp_ops->boot_secondary();
> > start_secondary();
> > ->init_secondary();
> > local_irq_enable();
> > <IRQ>
> > do something;
> > wake up softirqd;
> > try_to_wake_up();
> > select_fallback_rq();
> > /* select wrong cpu */
> > set_cpu_online();


> > This patchset fix the above issue as well as set_cpu_online is
> > called on the caller cpu.

> > BTW, I'm only running it on Cavium board because of limited source,
> > so if anyone is interested to test it on other board, that's great :)

> > Signed-off-by: Yong Zhang<yong.zhang0@xxxxxxxxx>

> > Yong Zhang (8):
> > MIPS: Octeon: delay enable irq to ->smp_finish()
> > MIPS: BMIPS: delay irq enable to ->smp_finish()
> > MIPS: SMTC: delay irq enable to ->smp_finish()
> > MIPS: Yosemite: delay irq enable to ->smp_finish()
> > MIPS: call ->smp_finish() a little late
> > MIPS: call set_cpu_online() on the uping cpu with irq disabled
> > MIPS: smp: Warn on too early irq enable
> > MIPS: sync-r4k: remove redundant irq operation

> This entire patch set (modulo the change log grammar items noted by Sergei):

   I noted not only change log grammar, also comment grammar. And a missing 
summary in commit reference. :-)

> Acked-by: David Daney <david.daney@xxxxxxxxxx>

WBR, Sergei
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