On Tue, 20 May 2014 20:30:05 +0200 Manfred Spraul <manf...@colorfullife.com> wrote:
> Hi Andrew, > > On 05/20/2014 12:46 AM, Andrew Morton wrote: > > On Sun, 18 May 2014 09:58:37 +0200 Manfred Spraul > > <manf...@colorfullife.com> wrote: > > > >> SUSv4 clearly defines how semncnt and semzcnt must be calculated: > >> A task waits on exactly one semaphore: > >> The semaphore from the first operation in the sop array that cannot > >> proceed. > >> > >> The Linux implementation never followed the standard, it tried to count all > >> semaphores that might be the reason why a task sleeps. > >> > >> This patch fixes that. > > What are the back-compatibility implications of this change? > A really good question: > - there is no application in Fedora that uses GETNCNT or GETZCNT. > - application that use only single-sop semop() are also safe, the > difference only affects complex apps. > - portable application are also safe, the new behavior is standard > compliant. > > But that's it. The old behavior existed in Linux from 0.99.something > until now. OK, thanks - I slurped your thoughts and Michael's into the changelog for posterity. > What about adding a WARN_ON_ONCE() if the case where the behavior > differs happens? > Should I write a patch? That sounds prudent. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
