Re: Incorrect cv_wait_sig() return values?

On Wed, Aug 04, 2010 at 10:36:24AM -0400, Andrew Gallatin wrote:
> Hi,
> 
> 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:
> 
> <...>
>       cv_wait_sig() and cv_timedwait_sig() return prematurely with a
>       value of EINTR or ERESTART if a signal is caught
> <...>
> 
> 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:
> 
> 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 = cv_wait_sig(&c, &m);
>         mtx_unlock(&m);
>         printf("cv_wait_sig returned %d\n", rc);
>         cv_destroy(&c);
>         mtx_destroy(&m);
> }
> 
> 
> 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:
> 
> 	Skeleton KLD loaded.
> 	cv_wait_sig returned -1
> 
> 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 = 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 = {
	"test",
	&test_load,
	NULL
};
DECLARE_MODULE(test, test_module, SI_SUB_KLD, SI_ORDER_FIRST);
MODULE_VERSION(test, 1);