From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Mon, 23 Feb 2004 20:12:59 +0000 Subject: Re: [patch] 2.4.25 sync unwind code with 2.6.3 Message-Id: <16442.24267.353386.287861@napali.hpl.hp.com> List-Id: References: <3792.1077504388@kao2.melbourne.sgi.com> In-Reply-To: <3792.1077504388@kao2.melbourne.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Keith> I am not happy with the kludge that avoids the deadlock on Keith> script-> lock, anybody got a better solution? The kludge Keith> assumes script-> that the first field in an ia64 rwsem is a Keith> spinlock. I have hit this unwind deadlock a couple of times Keith> during processing of asynchronous MCA events, so I want it Keith> fixed. What I did for libunwind is to avoid deadlock by falling back to uncached unwinding if necessary. That is, if a lock is taken, it just creates an unwind script on the local stack. It would be good to replace the built-in kernel unwinder with something based on libunwind. That would make it much easier to keep the code in sync (and libunwind is much better tested). I have been toying with the idea of doing this for 2.7, but it hasn't been very high priority to me because, for the most part, the kernel unwinder is good enough. --david