Date: Fri, 14 Dec 2018 14:45:16 -0500 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Subject: Re: sem_wait and EINTR On Wed, Dec 12, 2018 at 06:15:59AM +0100, Markus Wichmann wrote: > On Tue, Dec 11, 2018 at 07:32:38PM -0500, Rich Felker wrote: > > One other thought: would it be preferable for the EINTR suppression in > > the absence of interruptible signal handlers to be in __timedwait > > rather than sem_timedwait? Then any code using __timedwait would > > benefit from it. I'm not sure if there are other callers where it > > would help but it wouldn't hurt either. > > Nope, that would not help. I had a look at all users of SYS_futex that Perhaps help was the wrong word; I think you're right that there's nowhere else it matters and that all other callers already ignore EINTR unconditionally because they're supposed to. The only plausible improvement is avoiding spurious dec/inc cycle on the waiter count in some places. On the other hand it might be a nicer factorization (less ugly and linux-bug-specific logic in high level code, i.e. sem_timedwait) if the workaround were buried in low-level stuff (__timedwait). x> might be impacted by the kernel bug you mentioned (and followed them > back to the public interfaces that use them). Only __timedwait does > anything with the return value at all, and of all the users of > __timedwait(), sem_timedwait() is the only function even specified to > return EINTR. All others are specified to *never* return EINTR. At least > according to the manpages I have here (manpages-posix). > > So only sem_timedwait() needs this patch. For the other users it would > hurt conformance. I don't see how it could hurt conformance. Rich
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