Messages in this thread | | | Date | Wed, 10 Nov 2004 01:45:43 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] Documentation/preempt-locking.txt clarification |
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Thomas Hood <jdthood@yahoo.co.uk> wrote: > > On Wed, 2004-11-10 at 09:57, Andrew Morton wrote: > > I guess it's saying ... > > Thanks for the explanation. I include a new patch which incorporates > your example. I am in no position to judge the _truth_ of the > statements in this document; I am only hoping to _understand_ them. :)
I think the statement is in fact false. Ingo, what's your take on this paragraph, from preempt-locking.txt?
An additional concern is proper usage of local_irq_disable and local_irq_save. These may be used to protect from preemption, however, on exit, if preemption may be enabled, a test to see if preemption is required should be done. If these are called from the spin_lock and read/write lock macros, the right thing is done. They may also be called within a spin-lock protected region, however, if they are ever called outside of this context, a test for preemption should be made. Do note that calls from interrupt context or bottom half/ tasklets are also protected by preemption locks and so may use the versions which do not check preemption. - 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/
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