Messages in this thread | | | Date | Fri, 2 Jul 2004 14:35:24 +1000 | From | Nathan Scott <> | Subject | Re: [BUGS] [CHECKER] 99 synchronization bugs and a lock summary database |
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On Thu, Jul 01, 2004 at 06:01:00PM -0700, Yichen Xie wrote: > Hi all,
Hi there,
> We are a group of researchers at Stanford working on program analysis > algorithms. We have been building a precision enhanced program analysis > engine at Stanford, and our first application was to derive mutex/lock > behavior in the linux kernel. In the process, we found 99 likely > synchronization errors in linux kernel version 2.6.5: > > http://glide.stanford.edu/linux-lock/err1.html (69 errors) > http://glide.stanford.edu/linux-lock/err2.html (30 errors) > > ... > > As always, feedbacks and confirmations will be greatly appreciated!
From looking through the XFS reports, I suspect your tools aren't following the sv_wait semantics correctly (or else I'm misreading the code). Many of the reported XFS items stem from this - e.g. this one... [NOTE] BUG forgot to unlock before "goto try_again" (line 2293) ERROR: fs/xfs/xfs_log.c:2948: lock check failed! ERROR: fs/xfs/xfs_log.c:xlog_state_sync
the code in question does this:
try_again: s = LOG_LOCK(log); /* spin_lock(&log->l_icloglock); */ ... sv_wait(&iclog->ic_prev->ic_writesema, PSWP, &log->l_icloglock, s); already_slept = 1; goto try_again;
and the tools seem to be missing that the log->l_icloglock is unlocked by the sv_wait routine. Well, that or I've overlooked something that the tools have not. :)
A couple of the others were definately missed unlocks on error paths though (fixed now) - thanks!
cheers.
-- Nathan - 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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