[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/cio.c b/drivers/s390/cio/cio.c
index 6fec90eab00e82031b9634897c148080b62f5fd1..f27b2b866f5a07181eb07cb19fdce64d42f712da 100644 (file)
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -519,6 +519,7 @@ cio_validate_subchannel (struct subchannel *sch, struct subchannel_id schid)
        memset(sch, 0, sizeof(struct subchannel));
 
        spin_lock_init(&sch->lock);
+       mutex_init(&sch->reg_mutex);
 
        /* Set a name for the subchannel */
        snprintf (sch->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x", schid.ssid,

diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 0ca987344e07183f6b1d9bbbae5c040dc924bed9..4541c1af4b666aac7152bcbf9ef593a46074a0ef 100644 (file)
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -2,6 +2,7 @@
 #define S390_CIO_H
 
 #include "schid.h"
+#include <linux/mutex.h>
 
 /*
  * where we put the ssd info
@@ -87,7 +88,7 @@ struct orb {
 struct subchannel {
        struct subchannel_id schid;
        spinlock_t lock;        /* subchannel lock */
-
+       struct mutex reg_mutex;
        enum {
                SUBCHANNEL_TYPE_IO = 0,
                SUBCHANNEL_TYPE_CHSC = 1,

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 1d3be80797f81e1ed119a08394f872cc20700236..a09deea5d687f26ec4ce464e2cc608540ad6606f 100644 (file)
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -108,6 +108,24 @@ css_subchannel_release(struct device *dev)
 
 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 @@ css_register_subchannel(struct subchannel *sch)
        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 @@ css_evaluate_subchannel(struct subchannel_id schid, int slow)
                 * 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 @@ css_evaluate_subchannel(struct subchannel_id schid, int slow)
                 * 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);

diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h
index e210f89a24499c65f9bedea44df54d3e299c96d4..15f7f7cb0ec2c1a700d1410019aa4aea7d2d862d 100644 (file)
--- a/drivers/s390/cio/css.h
+++ b/drivers/s390/cio/css.h
@@ -136,6 +136,8 @@ extern struct bus_type css_bus_type;
 extern struct css_driver io_subchannel_driver;
 
 extern int css_probe_device(struct subchannel_id);
+extern int css_sch_device_register(struct subchannel *);
+extern void css_sch_device_unregister(struct subchannel *);
 extern struct subchannel * get_subchannel_by_schid(struct subchannel_id);
 extern int css_init_done;
 extern int for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *);

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 67f0de6aed33942ba078887e272287cdfca9ae7d..9db09870b2ae1dadd1e281301829673a687c3c1c 100644 (file)
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -280,7 +280,7 @@ ccw_device_remove_disconnected(struct ccw_device *cdev)
         * 'throw away device'.
         */
        sch = to_subchannel(cdev->dev.parent);
-       device_unregister(&sch->dev);
+       css_sch_device_unregister(sch);
        /* Reset intparm to zeroes. */
        sch->schib.pmcw.intparm = 0;
        cio_modify(sch);
@@ -625,7 +625,7 @@ ccw_device_do_unreg_rereg(void *data)
                                        other_sch->schib.pmcw.intparm = 0;
                                        cio_modify(other_sch);
                                }
-                               device_unregister(&other_sch->dev);
+                               css_sch_device_unregister(other_sch);
                        }
                }
                /* Update ssd info here. */
@@ -709,7 +709,7 @@ ccw_device_call_sch_unregister(void *data)
        struct subchannel *sch;
 
        sch = to_subchannel(cdev->dev.parent);
-       device_unregister(&sch->dev);
+       css_sch_device_unregister(sch);
        /* Reset intparm to zeroes. */
        sch->schib.pmcw.intparm = 0;
        cio_modify(sch);