Messages in this thread | | | Date | Thu, 19 Jul 2007 17:46:48 +0530 | From | "Satyam Sharma" <> | Subject | Re: [PATCH] [19/58] x86_64: Don't use softirq save locks in smp_call_function |
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On 7/19/07, Andi Kleen <ak@suse.de> wrote: > > It is not fully softirq safe anyways.
Ack
[ sorry, I remember having promised to send such a patch myself some time ago, but just forgot about it ... ]
> Can't do a WARN_ON unfortunately because it could trigger in the > panic case.
But this is not true at all. This function doesn't come anywhere on the panic codepath.
> +++ linux/arch/x86_64/kernel/smp.c > @@ -386,9 +386,9 @@ int smp_call_function_single (int cpu, v > return 0; > }
So I'd say we do need a:
WARN_ON(irqs_disabled() || in_interrupt());
or something right about here ...
> - spin_lock_bh(&call_lock); > + spin_lock(&call_lock); > __smp_call_function_single(cpu, func, info, nonatomic, wait); > - spin_unlock_bh(&call_lock); > + spin_unlock(&call_lock); > put_cpu(); > return 0; > }
And oh, by the way, you can safely go ahead and put that warning in smp_call_function() *also*.
Note that panic() -> smp_send_stop() -> calls into the lower-level __smp_call_function() directly.
So neither smp_call_function() nor smp_call_function_single() come in the panic codepath -- the warnings there would be okay.
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