Messages in this thread |  | | Date | Wed, 28 Nov 2001 01:00:40 +0530 | From | Dipankar Sarma <> | Subject | Re: smp_call_function & BH handlers |
| |
In article <Pine.LNX.4.33.0111271935520.23151-100000@localhost.localdomain> Ingo Molnar wrote:
> 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 ?
Thanks Dipankar -- Dipankar Sarma <dipankar@in.ibm.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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |