Messages in this thread | | | Date | Thu, 19 Jan 2006 14:48:11 -0200 | From | Marcelo Tosatti <> | Subject | Re: [PATCH] powerpc: remove useless spinlock from mpc83xx watchdog |
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On Thu, Jan 19, 2006 at 09:49:16AM +0000, Alan Cox wrote: > On Iau, 2006-01-19 at 00:58 -0600, Kumar Gala wrote: > > Since we can only open the watchdog once having a spinlock to protect > > multiple access is pointless. > > > > Signed-off-by: Kumar Gala <galak@kernel.crashing.org> > > NAK > > This is a common mistake. > > open is called on the open() call and is indeed in this case 'single > open', but file handles can be inherited and many users may have access > to a single file handle. > > eg > > f = open("/dev/watchdog", O_RDWR); > fork(); > while(1) { > write(f, "Boing", 5); > }
Oops.
At least 50% of the watchdog drivers rely solely on the "wdt_is_open" atomic variable and are broken with respect to synchronization. - 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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