Date: Mon, 12 Jan 2009 15:10:29 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Alexej Sokolov <bsd.quest@googlemail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: panic by unlocking of mutex in KLD Message-ID: <20090112141029.GA31108@skucha> In-Reply-To: <20090112134726.GA2988@debian.samsung.router> References: <20090112134726.GA2988@debian.samsung.router>
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On Mon, Jan 12, 2009 at 02:47:26PM +0100, Alexej Sokolov wrote: > Hello, > > by unloading of folowing module I have kernel panic. > > I would like to get any explanation about my mistake. > > #include <sys/param.h> > #include <sys/module.h> > #include <sys/kernel.h> > #include <sys/systm.h> > #include <sys/queue.h> > #include <sys/kernel.h> > #include <sys/kobj.h> > #include <sys/malloc.h> > #include <sys/types.h> > #include <sys/lock.h> > #include <sys/mutex.h> > > > struct mtx my_mtx; > > > /* Load handler */ > static int > load(struct module *mod, int cmd, void *arg) > { > int error = 0; > switch(cmd) { > case MOD_LOAD: > printf("Start! Addres of mutex = 0x%X \n", > &my_mtx); > mtx_init(&my_mtx, "My mutex name", "My mutex > type", MTX_DEF); > > mtx_lock(&my_mtx); > break; > case MOD_UNLOAD: > printf("Stop! Addres of mutex = 0x%X \n", > &my_mtx); > mtx_unlock(&my_mtx); > break; > default: > error = EOPNOTSUPP; > break; > } > > return (error); > } > > /* Module structure */ > static moduledata_t mod_data = { > "mymod", > load, > NULL > }; > MODULE_VERSION (kld, 1); > DECLARE_MODULE (kld, mod_data, SI_SUB_DRIVERS, SI_ORDER_MIDDLE); > > Acutally it panics even on loading. :) Mutexes have owners. It panics on loading because processes cannot return to userland with locks held. It panics on unloading (in your case) because curproc != my_mtx's owner. -- Mateusz Guzik <mjguzik at gmail.com>
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