Date: Wed, 24 Aug 2011 22:32:02 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Slawa Olhovchenkov <slw@zxy.spb.ru> Cc: freebsd-stable@freebsd.org Subject: Re: sigwait return 4 Message-ID: <20110824193202.GZ17489@deviant.kiev.zoral.com.ua> In-Reply-To: <20110824192446.GB48394@zxy.spb.ru> References: <20110824181907.GA48394@zxy.spb.ru> <20110824190703.GY17489@deviant.kiev.zoral.com.ua> <20110824192446.GB48394@zxy.spb.ru>
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[-- Attachment #1 --] On Wed, Aug 24, 2011 at 11:24:46PM +0400, Slawa Olhovchenkov wrote: > On Wed, Aug 24, 2011 at 10:07:03PM +0300, Kostik Belousov wrote: > > > On Wed, Aug 24, 2011 at 10:19:07PM +0400, Slawa Olhovchenkov wrote: > > > System is 8.2-RELEASE (GENERIC), amd64. > > > Application -- i386 for freebsd7. > > > > > > In ktrace dump I find some strange result: > > > > > > 22951 100556 kas-milter CALL sigwait(0xffdfdf80,0xffdfdf7c) > > > 22951 100556 kas-milter RET sigwait 4 > > > 22951 100556 kas-milter PSIG SIGUSR2 caught handler=0x804c0f0 mask=0x4003 code=0x0 > > > > > > RET sigwait 4 confused me, and, I think, confused application too. > > > > > > man sigwait: > > > > > > ERRORS > > > The sigwait() system call will fail if: > > > > > > [EINVAL] The set argument specifies one or more invalid signal > > > numbers. > > > > > > [EFAULT] Any arguments point outside the allocated address > > > space or there is a memory protection fault. > > > > > > > > > How sigwait can return '4'? > > > May be EINTR, converted from ERESTART? But kern_sigtimedwait from sigwait must > > > be called with timeout == NULL... > > > > > > > What should the system do for a delivered signal not present in the set ? > > I guess this is the case of your ktrace. > > > > Looking at the SUSv4, I see no mention of the situation, but in Oracle > > SunOS 5.10 man page for sigwait(2), it is said explicitely > > EINTR The wait was interrupted by an unblocked, caught signal. > > I don't think you right in this case. > This is kas-milter and in this thread (this is multi-thread > application) kas-milter wait for USR2 for reload config. > > System return from sigwait only on USR2, but not each return w/ > non-zero return code. > > On freebsd7 this application don't complain about sigwait's return value. Could it be that some other thread has the signal unblocked ? (You can verify this with procstat -j). Can you write the self-contained test case that demonstrates the behaviour ? [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk5VUbIACgkQC3+MBN1Mb4ji3ACfUNBxLk0D8CypSdqePKjYZd/O PKIAoK+vnfxFTMMG+iBPjeOGz2GdGNq1 =IHXv -----END PGP SIGNATURE-----
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