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Date: Tue, 15 May 2012 13:25:32 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: Peter Zijlstra <peterz@...radead.org> Cc: LKML <linux-kernel@...r.kernel.org>, RT <linux-rt-users@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>, Clark Williams <williams@...hat.com> Subject: Re: [RFC][PATCH RT] rwsem_rt: Another (more sane) approach to mulit reader rt locks On Tue, 2012-05-15 at 11:42 -0400, Steven Rostedt wrote: > On Tue, 2012-05-15 at 17:06 +0200, Peter Zijlstra wrote: > > On Tue, 2012-05-15 at 10:03 -0400, Steven Rostedt wrote: > > > > > > where readers may nest (the same task may grab the same rwsem for > > > read multiple times), but only one task may hold the rwsem at any > > > given > > > time (for read or write). > > > > Humm, that sounds iffy, rwsem isn't a recursive read lock only rwlock_t > > is. > > In that case, current -rt is broken. As it has it being a recursive lock > (without my patch). > Why wouldn't it be recursive. If two different tasks are allowed to grab a read lock at the same time, why can't the same task grab a read lock twice? As long as it releases it the same amount of times. Now you can't grab a read lock if you have the write lock. -- Steve -- 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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