[S390] subchannel register/unregister mutex.
Add a reg_mutex to prevent unregistering a subchannel before it has been
registered. Since 2.6.17, we've seen oopses in kslowcrw when a device is
found to be not operational during sense id when doing initial device
recognition; it is not clear yet why that particular problem was not (yet)
observed with earlier kernels...
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 1d3be80..a09deea 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -108,6 +108,24 @@
extern int css_get_ssd_info(struct subchannel *sch);
+
+int css_sch_device_register(struct subchannel *sch)
+{
+ int ret;
+
+ mutex_lock(&sch->reg_mutex);
+ ret = device_register(&sch->dev);
+ mutex_unlock(&sch->reg_mutex);
+ return ret;
+}
+
+void css_sch_device_unregister(struct subchannel *sch)
+{
+ mutex_lock(&sch->reg_mutex);
+ device_unregister(&sch->dev);
+ mutex_unlock(&sch->reg_mutex);
+}
+
static int
css_register_subchannel(struct subchannel *sch)
{
@@ -119,7 +137,7 @@
sch->dev.release = &css_subchannel_release;
/* make it known to the system */
- ret = device_register(&sch->dev);
+ ret = css_sch_device_register(sch);
if (ret)
printk (KERN_WARNING "%s: could not register %s\n",
__func__, sch->dev.bus_id);
@@ -250,7 +268,7 @@
* The device will be killed automatically.
*/
cio_disable_subchannel(sch);
- device_unregister(&sch->dev);
+ css_sch_device_unregister(sch);
/* Reset intparm to zeroes. */
sch->schib.pmcw.intparm = 0;
cio_modify(sch);
@@ -264,7 +282,7 @@
* away in any case.
*/
if (!disc) {
- device_unregister(&sch->dev);
+ css_sch_device_unregister(sch);
/* Reset intparm to zeroes. */
sch->schib.pmcw.intparm = 0;
cio_modify(sch);