![]() | ||||||||||
Messages in this thread |
Junio C Hamano <gitster@pobox.com> wrote: > Is it just me who feels this comment that says "in_atomic() is not a way > to tell if we are in atomic reliably and cannot be used for such and such" > very reader-unfriendly? Ok, maybe the macro is not reliable and is not > meant to be used for the purpose its name seems to suggest (at least to a > non-kernel person). An inevitable question is, then what is it good for? > What's the right situation to use this macro? The "right situation" would appear to be "you're deep in the mm code and really know what you're doing." It is not a useful way for code to determine whether it's running in atomic context - as was discussed elsewhere in the thread, that information really needs to be passed in by the caller. Look for more detail on LWN, probably later today :) > I guess an additional comment "even if this says no, you could still be in > atomic, but if this says yes, then you definitely are in atomic and cannot > sleep" may help unconfuse a clueless reader like myself. The point being that "you just *might* be in atomic context, where sleeping would be a bad idea, but I can't tell you" really isn't all that useful. It's a trap which can only lead to incorrect code. What really needs to happen, IMHO, is that this macro should be ripped out of hardirq.h entirely and cleverly hidden somewhere. That can't be done, though, until the drivers which use it are fixed. But while that is happening, we can at least put up a skull-and-crossbones sign to discourage others from making the same mistake. jon -- 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/ | |||||||||
| Last update: 2008-03-25 13:47 [from the cache] ©2003-2008 | ||||||||||