Messages in this thread | | | Date | Mon, 7 Jun 1999 23:56:23 +0200 (CEST) | From | Ingo Molnar <> | Subject | Re: adding to wait queue |
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On Mon, 7 Jun 1999, Raj, Ashok wrote:
> Have a silly question. > > when i add to wait_queue() should i need a spinlock around it in a MP > system? or > would doing a > > save_flags(); cli() before doing a add_wait_queue() be sufficient.
add_wait_queue()/remove_wait_queue() functions are MP-safe. So for the 'typical' case where the waitqueue is on the local kernel stack you need no locking at all. The generic rule is that typically all kernel services are MP-safe (get_free_pages(), kmalloc(), slab, signal sending, etc.)
[in some cases we use __add_waitqueue which is a non-spinlock version, in that case we have to make sure to hold the spinlock - the majority of uses doesnt have to do this]
-- mingo
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