Date: Wed, 01 Jun 2011 09:07:38 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: "Kenneth D. Merry" <ken@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r222537 - in head/sys: kern sys Message-ID: <4DE5D72A.1020405@FreeBSD.org> In-Reply-To: <201105311729.p4VHTwrZ033296@svn.freebsd.org> References: <201105311729.p4VHTwrZ033296@svn.freebsd.org>
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on 31/05/2011 20:29 Kenneth D. Merry said the following: > + mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN); Sorry that I didn't gather myself together for a review before this change got actually committed. Do you see any reason not to make this spinlock recursive? I am a little bit worried about "exotic" situations like receiving an NMI in the middle of printing and wanting to print in the NMI context, or similar things that penetrate contexts with disabled interrupts - e.g. Machine Check Exception. Also it's not clear to me if there won't any bigger damage in the situations like those described above. P.S. I have been thinking about fixing the problem in a different fashion, via reserving portions of dmesg buffer for a whole message using CAS: http://lists.freebsd.org/pipermail/freebsd-hackers/2010-April/031535.html -- Andriy Gapon
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