Date: Mon, 4 Oct 2004 12:29:43 -0400 From: John Baldwin <jhb@FreeBSD.org> To: David Schultz <das@FreeBSD.org> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern kern_fork.c Message-ID: <200410041229.43350.jhb@FreeBSD.org> In-Reply-To: <20041004153854.GA14022@VARK.MIT.EDU> References: <200410010501.i9151US7086474@repoman.freebsd.org> <200410041034.32221.jhb@FreeBSD.org> <20041004153854.GA14022@VARK.MIT.EDU>
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On Monday 04 October 2004 11:38 am, David Schultz wrote: > On Mon, Oct 04, 2004, John Baldwin wrote: > > On Friday 01 October 2004 01:01 am, David Schultz wrote: > > > das 2004-10-01 05:01:29 UTC > > > > > > FreeBSD src repository > > > > > > Modified files: > > > sys/kern kern_fork.c > > > Log: > > > Avoid calling _PHOLD(p1) with p2's lock held, since _PHOLD() > > > may block to swap in p1. Instead, call _PHOLD earlier, at a > > > point where the only lock held happens to be p1's. > > > > FWIW, I don't think this can actually happen because curthread belonging > > to p1 is executing and it wouldn't be executing unless it was swapped in, > > so I don't think that PHOLD could ever have blocked. > > Yes, you're right. I'll revert this one. Shall I also change the > _PHOLD() into simply p1->p_lock++ (and similarly for _PRELE()) to > avoid the useless test? Nah, I would just leave it as _PHOLD() since it's easier when reading the code to see the matching pair. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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