Re: [rfc] "fair" rw spinlocks

From: Eric W. Biederman
Date: Mon Dec 07 2009 - 18:20:18 EST


Andi Kleen <andi@xxxxxxxxxxxxxx> writes:

> ebiederm@xxxxxxxxxxxx (Eric W. Biederman) writes:
>
>> "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> writes:
>>>
>>> Is it required that all of the processes see the signal before the
>>> corresponding interrupt handler returns? (My guess is "no", which
>>> enables a trick or two, but thought I should ask.)
>>
>> Not that I recall. I think it is just an I/O completed signal.
>
> Wasn't there the sysrq SAK too? That one definitely would need
> to be careful about synchronicity.

SAK from sysrq is done through schedule work, I seem to recall the
locking being impossible otherwise. There is also send_sig_all and a
few others from sysrq. I expect we could legitimately make them
schedule_work as well if needed.

Eric
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