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On Sat, Nov 25, 2006 at 05:00:27PM +0100, Ingo Oeser wrote: > Ok, I will comment it. But I'll NOT comment on the implementation. > I'll prove you instead, that timout based locking is non-sense. Your proof misses a case and is thus invalid. > What should the timout mutex_timeout() prevent? Usually the answer is > "if sombody hangs on a mutex forever ...?" and people tell you "ok, that is > a deadlock -> fix your code not to deadlock instead." > Then they tell you "Ok, but if somebody takes a mutex too long?" > and people will answer "ok, then this is a livelock -> fix your code not to > livelock." > > Another answer is "I like to block until sth. happens wihin a specific time frame" > -> fine, this is accomplished by wait_event_timout (which blocks only you and > not every other user of the mutex). In the qla case, the mutex can be acquired by a thread which then waits for the hardware to do something. If the hardware locks up, it is preferable that the system not hang. > I know why ACPI needs it (API requirement) and I think the qla???-driver > just needs to be fixed to work without it and nobody did it yet. Since Christoph is the one who has his name on it: /* XXX(hch): crude hack to emulate a down_timeout() */ I assumed that he'd spent enough time thinking about it that fixing it really wasn't feasible. - 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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