gigaset: fix Oops on module unload regression

The card state mutex was only initialized when a device was connected,
but used during unload unconditionally, leading to an Oops if a driver
was loaded and unloaded again without ever connecting a device.

Fix this by initializing the mutex as soon as the structure is allocated.
Also add a missing mutex unlock revealed in the same execution path.

This fixes a possible Oops in 2.6.25-rc that was introduced by commit
e468c04894f36045cf93d1384183a461014b6840 ("Gigaset: permit module
unload").

Thanks to Roland Kletzing for reporting this problem.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Tested-by: Roland Kletzing <devzero@web.de>
Cc: Hansjoerg Lipp <hjlipp@web.de>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/isdn/gigaset/common.c b/drivers/isdn/gigaset/common.c
index aacedec..827c32c 100644 (file)
--- a/drivers/isdn/gigaset/common.c
+++ b/drivers/isdn/gigaset/common.c
@@ -637,7 +637,6 @@ struct cardstate *gigaset_initcs(struct gigaset_driver *drv, int channels,
                err("maximum number of devices exceeded");
                return NULL;
        }
-       mutex_init(&cs->mutex);
 
        gig_dbg(DEBUG_INIT, "allocating bcs[0..%d]", channels - 1);
        cs->bcs = kmalloc(channels * sizeof(struct bc_state), GFP_KERNEL);
@@ -898,8 +897,10 @@ int gigaset_shutdown(struct cardstate *cs)
 {
        mutex_lock(&cs->mutex);
 
-       if (!(cs->flags & VALID_MINOR))
+       if (!(cs->flags & VALID_MINOR)) {
+               mutex_unlock(&cs->mutex);
                return -1;
+       }
 
        cs->waiting = 1;
 
@@ -1086,6 +1087,7 @@ struct gigaset_driver *gigaset_initdriver(unsigned minor, unsigned minors,
                drv->cs[i].driver = drv;
                drv->cs[i].ops = drv->ops;
                drv->cs[i].minor_index = i;
+               mutex_init(&drv->cs[i].mutex);
        }
 
        gigaset_if_initdriver(drv, procname, devname);