Date: Wed, 4 Aug 2010 18:46:04 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: current@freebsd.org Subject: Re: Incorrect cv_wait_sig() return values? Message-ID: <20100804154604.GY22295@deviant.kiev.zoral.com.ua> In-Reply-To: <4C597AE8.5090703@cs.duke.edu> References: <4C597AE8.5090703@cs.duke.edu>
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--eci7kgoNre1oTc2t Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Aug 04, 2010 at 10:36:24AM -0400, Andrew Gallatin wrote: > Hi, >=20 > I recently noticed that cv_wait_sig() will return -1 > rather than EINTR when a SIGINT is delivered. This is > in contrast to CONDVAR(9) which states: >=20 > <...> > cv_wait_sig() and cv_timedwait_sig() return prematurely with a > value of EINTR or ERESTART if a signal is caught > <...> >=20 > To demonstrate the problem outside my out-of-tree driver, I > took the skeleton driver from > http://www.captain.at/programming/freebsd/ > and added the following function, invoked at module > load: >=20 > static struct mtx m; > static struct cv c; >=20 > static void > cv_test(void) > { > int rc; >=20 > mtx_init(&m, "skel_m", MTX_DEF, MTX_DEF); > cv_init(&c, "skel_c"); > mtx_lock(&m); > rc =3D cv_wait_sig(&c, &m); > mtx_unlock(&m); > printf("cv_wait_sig returned %d\n", rc); > cv_destroy(&c); > mtx_destroy(&m); > } >=20 >=20 > I load the module, and I ^C kldload after a few seconds > to break out of the cv_wait_sig(), which results in this > output on console: >=20 > Skeleton KLD loaded. > cv_wait_sig returned -1 >=20 > Am I doing something wrong, or are condvars broken? > I've tried to track this down with dtrace, but failed.. What version of the system do you use ? I cannot confirm this on the HEAD from several hours ago with the following test module. On the SIGINT I get `4' printed, which is EINTR. #include <sys/param.h> #include <sys/systm.h> #include <sys/kernel.h> #include <sys/lock.h> #include <sys/module.h> #include <sys/mutex.h> #include <sys/condvar.h> static struct mtx m; static struct cv c; static void cv_test(void) { int rc; mtx_init(&m, "skel_m", MTX_DEF, MTX_DEF); cv_init(&c, "skel_c"); mtx_lock(&m); rc =3D cv_wait_sig(&c, &m); mtx_unlock(&m); printf("cv_wait_sig returned %d\n", rc); cv_destroy(&c); mtx_destroy(&m); } static int test_load(module_t mod, int cmd, void *arg) { switch (cmd) { case MOD_LOAD: cv_test(); break; } return (0); } static moduledata_t test_module =3D { "test", &test_load, NULL }; DECLARE_MODULE(test, test_module, SI_SUB_KLD, SI_ORDER_FIRST); MODULE_VERSION(test, 1); --eci7kgoNre1oTc2t Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkxZizwACgkQC3+MBN1Mb4ikyACgsI1KkPSTDHHUd0frioHhdl+3 esIAn3GHS4Mjla1lJV6daNoqadwgpPps =I/Zp -----END PGP SIGNATURE----- --eci7kgoNre1oTc2t--
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