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On Fri, 21 Mar 2008, Andrew Morton wrote: > On Fri, 21 Mar 2008 10:53:11 +0100 Jean Delvare <khali@linux-fr.org> wrote: > > > On Thu, 20 Mar 2008 20:17:23 -0700, Andrew Morton wrote: > > > in_atomic() is for core kernel use only. (...) > > > > Then why is it made available to drivers through <linux/hardirq.h>? > > Because we suck. > > > If > > it's such a dangerous macro to call from drivers, it shouldn't be made > > available, or at the very least there should be a big fat warning in > > <linux/hardirq.h> that drivers aren't supposed to use it. This would > > have avoided the 23 uses cases in drivers we have right now. > > True. There's also a section about in_atomic() in the Linux Device Drivers (3rd ed.) book which may have contributed to the confusion. On p. 198: A function related to in_interrupt() is in_atomic(). Its return value is nonzero whenever scheduling is not allowed; this includes hardware and software interrupt contexts as well as any time when a spinlock is held. In the latter case, current may be valid, but access to user space is forbidden, since it can cause scheduling to happen. Whenever you are using in_interrupt(), you should really consider whether in_atomic() is what you actually mean. Both functions are declared in <asm/hardirq.h>. Alan Stern -- 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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