Date: Tue, 21 Oct 2003 23:45:31 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: mjacob@feral.com Cc: 'Kris Kennaway' <kris@obsecurity.org> Subject: Re: Sleeping on "isp_mboxwaiting" with the following non-sleepablelocks held: Message-ID: <13910.1066772731@critter.freebsd.dk> In-Reply-To: Your message of "Tue, 21 Oct 2003 14:30:21 PDT." <000801c3981a$8abc6540$23a610ac@win2k>
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In message <000801c3981a$8abc6540$23a610ac@win2k>, "Matthew Jacob" writes: >So? How about some details and context? > >I thought was told that being able to use locks in HBAs is fine. I had >them on for a while, and then had them off. I turned them on again over >a month ago. I'm somewhat surprised to see that a problem shows up now. > >*I* do the right thing with locks, IMO. I hold them in my module when I >enter and release them if/when I leave. Seeing a lock held by some >random caller causing me to blow up to me seems to be a hole in the >architecture, but I'd be the first to admit that I hardly am up to date >on what the rules of the road are now so such an opinion is >ill-informed. The lock held in this case, is not "some random caller", that is a mutex held specifically to expose device drivers which try to sleep in their ->strategy() function. You cannot sleep in the strategy() function because that would hold op I/O, and therefore likely lead to deadlock. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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