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Date: Wed, 18 Jun 2014 18:43:59 +0200 From: Oleg Nesterov <oleg@...hat.com> To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Steven Rostedt <rostedt@...dmis.org>, Linus Torvalds <torvalds@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>, Andrew Morton <akpm@...ux-foundation.org>, Ingo Molnar <mingo@...nel.org>, Clark Williams <williams@...hat.com> Subject: Re: safety of *mutex_unlock() (Was: [BUG] signal: sighand unprotected when accessed by /proc) On 06/17, Paul E. McKenney wrote: > > + if (drop_boost_mutex) { > + rt_mutex_unlock(&rnp->boost_mtx); > complete(&rnp->boost_completion); Well, I still do not understand this ->boost_completion... > - /* Wait until boostee is done accessing mtx before reinitializing. */ > + /* Wait for boostee to be done w/boost_mtx before reinitializing. */ > wait_for_completion(&rnp->boost_completion); OK, at least we have a comment. But let me repeat. Thomas has already fixed rt_mutex, unlock is atomic. It doesn't touch this memory after it makes another lock() possible. And (contrary to what I said initially) we can rely on this because -rt converts spinlock_t into rt_mutex ? Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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