On Sun, Mar 11, 2012 at 8:06 PM, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> wrote: > On Sun, Mar 11, 2012 at 07:47:27PM +0530, santosh prasad nayak wrote: >> Not to use in_atomic() in driver code. >> >> Following article inspired me to do the change. >> http://lwn.net/Articles/274695/ >> >> "in_atomic() is for core kernel use only. Because in special >> circumstances (ie: kmap_atomic()) we run inc_preempt_count() even on >> non-preemptible kernels to tell the per-arch fault handler that it was >> invoked by copy_*_user() inside kmap_atomic(), and it must fail. >> In other words, in_atomic() works in a specific low-level situation, >> but it was never meant to be used in a wider context. Its placement in >> hardirq.h next to macros which can be used elsewhere was, thus, almost >> certainly a mistake. As Alan Stern pointed out, the fact that Linux >> Device Drivers recommends the use of in_atomic() will not have helped >> the situation. Your editor recommends that the authors of that book be >> immediately sacked. " >> >> In the present case, we just check whether its an IRQ context or user >> context. So for that >> we can use "in_interrupt()". >> >> Greg also mentions the same in the following mail. >> http://www.spinics.net/lists/newbies/msg43402.html > > In which case, we'll just have to do mdelay() and forget about allowing > anything else to run for the 20ms that we need to sleep. Sucky but > that's the way things are. mdelay() or msleep() are there before. I did not change that. my point is : in_atomic() vs "in_interrupt()". We should avoid to use "in_atomic()" in driver code. In the present case to check IRQ context "in_interrupt()" should be preferred. regards Santosh regards Santosh -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
