Date: Thu, 03 Mar 2005 12:22:01 -0800 From: Julian Elischer <julian@elischer.org> To: David Schultz <das@FreeBSD.org> Cc: John Baldwin <jhb@FreeBSD.org> Subject: Re: cvs commit: src/sys/kern kern_sig.c Message-ID: <422771E9.6070405@elischer.org> In-Reply-To: <20050303052902.GA14011@VARK.MIT.EDU> References: <200503021343.j22DhpQ3075008@repoman.freebsd.org> <200503020915.28512.jhb@FreeBSD.org> <4226446B.7020406@freebsd.org> <20050303033115.GA13174@VARK.MIT.EDU> <42269DB0.6070107@freebsd.org> <20050303052902.GA14011@VARK.MIT.EDU>
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David Schultz wrote: >On Thu, Mar 03, 2005, David Xu wrote: > > >> >>This only partly resolves the problem, if function A call B, B call C, >>C is unknown to A, >>and C does a msleep(), problem still lhappens. >>However, if there needs a flag, I would like PNOSWAP for msleep just >>like PCATCH >>does. >> >> > >You have to worry about that anyway, though. A and B need to know >that they're not allowed to hold locks across the calls if C calls >msleep(), for instance. Anyway, your proposal if having a flag >for msleep() is basically the same as my proposal of having a >separate function. (The only difference is that adding a separate >function doesn't break the ABI.) So it sounds like we're more or >less in agreement here. > > > >>>The alternative, of course, is to just fix the code that assumes >>>that swapping doesn't exist. >>> >>> >>> >>First find all code written in such way, but it is not that easy. >> >> > >True. If we changed msleep() to disable swapping by default, then >we wouldn't have to worry about correctness problems related to >missing some. > > adding the flag to ENABLE swapping would be ABI compatible.
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