> On Tue, 27 Nov 2001, Maneesh Soni wrote:
>> I am working with Dipankar on Read-Copy Update, and experimenting with
>> smp_call_function(). We believed the comments for this routine and
>> faced this problem. That's why this question came. I have not yet
>> searched kernel sources for such places hence not sure whether there
>> are really such places or not.
> we had similar lockup problems before, eg. TLB flushes initiated from
> IRQ/BH contexts - which is illegal now. Generally it's not safe to assume
> that every CPU is responsive to synchronous events triggered from IRQ/BH
> contexts. Every read_lock user is prone to this problem.
Thanks for the clarification. Should we update the
function header for smp_call_function() to say that it is illegal
to use it from both IRQ and BH contexts ?
Along the same lines, I am wondering if nowait broadcast IPI sender
waiting for IPI handlers to start in all other CPUs is a by-product
of the implementation. I can see the need for two types of
such IPIs - 1. send the broadcast IPI and forget about it and
2. send the broadcast IPI and wait for completion of the handlers.
Is there a need for the linux kernel to have a broadcast IPI
mechanism that waits for the start of the IPI handler elsewhere but
not till the end ?
-- Dipankar Sarma <email@example.com> http://lse.sourceforge.net Linux Technology Center, IBM Software Lab, Bangalore, India. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to firstname.lastname@example.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/