[PATCH] s390: deadlock in dasd_devmap

Reintroduce a read-only copy of the devmap features in the device struct.
This is necessary to solve a deadlock on the dasd_devmap_lock which is
acquired by dasd_get_features called from the dasd tasklet.  The current
implementation of devmap doesn't allow to call any devmap function from
interrupt or softirq context.

Signed-off-by: Horst Hummel <horst.hummel@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index d5f5398..8fc891a 100644 (file)
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -7,7 +7,7 @@
  * Bugreports.to..: <Linux390@de.ibm.com>
  * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
  *
- * $Revision: 1.165 $
+ * $Revision: 1.167 $
  */
 
 #include <linux/config.h>
@@ -1131,17 +1131,13 @@ __dasd_process_blk_queue(struct dasd_device * device)
        request_queue_t *queue;
        struct request *req;
        struct dasd_ccw_req *cqr;
-       int nr_queued, feature_ro;
+       int nr_queued;
 
        queue = device->request_queue;
        /* No queue ? Then there is nothing to do. */
        if (queue == NULL)
                return;
 
-       feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-       if (feature_ro < 0)     /* no devmap */
-               return;
-
        /*
         * We requeue request from the block device queue to the ccw
         * queue only in two states. In state DASD_STATE_READY the
@@ -1162,7 +1158,8 @@ __dasd_process_blk_queue(struct dasd_device * device)
                nr_queued < DASD_CHANQ_MAX_SIZE) {
                req = elv_next_request(queue);
 
-               if (feature_ro && rq_data_dir(req) == WRITE) {
+               if (device->features & DASD_FEATURE_READONLY &&
+                   rq_data_dir(req) == WRITE) {
                        DBF_DEV_EVENT(DBF_ERR, device,
                                      "Rejecting write request %p",
                                      req);
@@ -1814,17 +1811,13 @@ dasd_generic_set_online (struct ccw_device *cdev,
 
 {
        struct dasd_device *device;
-       int feature_diag, rc;
+       int rc;
 
        device = dasd_create_device(cdev);
        if (IS_ERR(device))
                return PTR_ERR(device);
 
-       feature_diag = dasd_get_feature(cdev, DASD_FEATURE_USEDIAG);
-       if (feature_diag < 0)
-               return feature_diag;
-
-       if (feature_diag) {
+       if (device->features & DASD_FEATURE_USEDIAG) {
                if (!dasd_diag_discipline_pointer) {
                        printk (KERN_WARNING
                                "dasd_generic couldn't online device %s "

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index d948566..bda896d 100644 (file)
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -11,7 +11,7 @@
  * functions may not be called from interrupt context. In particular
  * dasd_get_device is a no-no from interrupt context.
  *
- * $Revision: 1.40 $
+ * $Revision: 1.43 $
  */
 
 #include <linux/config.h>
@@ -513,6 +513,7 @@ dasd_create_device(struct ccw_device *cdev)
        if (!devmap->device) {
                devmap->device = device;
                device->devindex = devmap->devindex;
+               device->features = devmap->features;
                get_device(&cdev->dev);
                device->cdev = cdev;
                rc = 0;
@@ -643,6 +644,8 @@ dasd_ro_store(struct device *dev, struct device_attribute *attr, const char *buf
                devmap->features |= DASD_FEATURE_READONLY;
        else
                devmap->features &= ~DASD_FEATURE_READONLY;
+       if (devmap->device)
+               devmap->device->features = devmap->features;
        if (devmap->device && devmap->device->gdp)
                set_disk_ro(devmap->device->gdp, ro_flag);
        spin_unlock(&dasd_devmap_lock);
@@ -758,7 +761,8 @@ dasd_set_feature(struct ccw_device *cdev, int feature, int flag)
                devmap->features |= feature;
        else
                devmap->features &= ~feature;
-
+       if (devmap->device)
+               devmap->device->features = devmap->features;
        spin_unlock(&dasd_devmap_lock);
        return 0;
 }

diff --git a/drivers/s390/block/dasd_genhd.c b/drivers/s390/block/dasd_genhd.c
index 96c4934..a601c9a 100644 (file)
--- a/drivers/s390/block/dasd_genhd.c
+++ b/drivers/s390/block/dasd_genhd.c
@@ -9,7 +9,7 @@
  *
  * gendisk related functions for the dasd driver.
  *
- * $Revision: 1.50 $
+ * $Revision: 1.51 $
  */
 
 #include <linux/config.h>
@@ -31,16 +31,12 @@ int
 dasd_gendisk_alloc(struct dasd_device *device)
 {
        struct gendisk *gdp;
-       int len, feature_ro;
+       int len;
 
        /* Make sure the minor for this device exists. */
        if (device->devindex >= DASD_PER_MAJOR)
                return -EBUSY;
 
-       feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-       if (feature_ro < 0)
-               return feature_ro;
-
        gdp = alloc_disk(1 << DASD_PARTN_BITS);
        if (!gdp)
                return -ENOMEM;
@@ -75,7 +71,7 @@ dasd_gendisk_alloc(struct dasd_device *device)
 
        sprintf(gdp->devfs_name, "dasd/%s", device->cdev->dev.bus_id);
 
-       if (feature_ro)
+       if (device->features & DASD_FEATURE_READONLY)
                set_disk_ro(gdp, 1);
        gdp->private_data = device;
        gdp->queue = device->request_queue;

diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index a9f38b2..9fab04f 100644 (file)
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -6,7 +6,7 @@
  * Bugreports.to..: <Linux390@de.ibm.com>
  * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999,2000
  *
- * $Revision: 1.64 $
+ * $Revision: 1.65 $
  */
 
 #ifndef DASD_INT_H
@@ -286,6 +286,7 @@ struct dasd_device {
        unsigned int bp_block;          /* bytes per block */
        unsigned int s2b_shift;         /* log2 (bp_block/512) */
        unsigned long flags;            /* per device flags */
+       unsigned short features;        /* copy of devmap-features (read-only!) */
 
        /* Device discipline stuff. */
        struct dasd_discipline *discipline;

diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
index 980c555..789595b 100644 (file)
--- a/drivers/s390/block/dasd_ioctl.c
+++ b/drivers/s390/block/dasd_ioctl.c
@@ -7,7 +7,7 @@
  * Bugreports.to..: <Linux390@de.ibm.com>
  * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
  *
- * $Revision: 1.45 $
+ * $Revision: 1.47 $
  *
  * i/o controls for the dasd driver.
  */
@@ -296,7 +296,6 @@ dasd_ioctl_format(struct block_device *bdev, int no, long args)
 {
        struct dasd_device *device;
        struct format_data_t fdata;
-       int feature_ro;
 
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
@@ -308,10 +307,7 @@ dasd_ioctl_format(struct block_device *bdev, int no, long args)
        if (device == NULL)
                return -ENODEV;
 
-       feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-       if (feature_ro < 0)
-               return feature_ro;
-       if (feature_ro)
+       if (device->features & DASD_FEATURE_READONLY)
                return -EROFS;
        if (copy_from_user(&fdata, (void __user *) args,
                           sizeof (struct format_data_t)))
@@ -384,7 +380,7 @@ dasd_ioctl_information(struct block_device *bdev, int no, long args)
        struct dasd_device *device;
        struct dasd_information2_t *dasd_info;
        unsigned long flags;
-       int rc, feature_ro;
+       int rc;
        struct ccw_device *cdev;
 
        device = bdev->bd_disk->private_data;
@@ -394,10 +390,6 @@ dasd_ioctl_information(struct block_device *bdev, int no, long args)
        if (!device->discipline->fill_info)
                return -EINVAL;
 
-       feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-       if (feature_ro < 0)
-               return feature_ro;
-
        dasd_info = kmalloc(sizeof(struct dasd_information2_t), GFP_KERNEL);
        if (dasd_info == NULL)
                return -ENOMEM;
@@ -427,7 +419,8 @@ dasd_ioctl_information(struct block_device *bdev, int no, long args)
            (dasd_check_blocksize(device->bp_block)))
                dasd_info->format = DASD_FORMAT_NONE;
 
-       dasd_info->features |= feature_ro;
+       dasd_info->features |=
+               ((device->features & DASD_FEATURE_READONLY) != 0);
 
        if (device->discipline)
                memcpy(dasd_info->type, device->discipline->name, 4);

diff --git a/drivers/s390/block/dasd_proc.c b/drivers/s390/block/dasd_proc.c
index 43c34f8..fff9020 100644 (file)
--- a/drivers/s390/block/dasd_proc.c
+++ b/drivers/s390/block/dasd_proc.c
@@ -9,7 +9,7 @@
  *
  * /proc interface for the dasd driver.
  *
- * $Revision: 1.32 $
+ * $Revision: 1.33 $
  */
 
 #include <linux/config.h>
@@ -55,7 +55,6 @@ dasd_devices_show(struct seq_file *m, void *v)
 {
        struct dasd_device *device;
        char *substr;
-       int feature;
 
        device = dasd_device_from_devindex((unsigned long) v - 1);
        if (IS_ERR(device))
@@ -79,10 +78,7 @@ dasd_devices_show(struct seq_file *m, void *v)
        else
                seq_printf(m, " is ????????");
        /* Print devices features. */
-       feature = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
-       if (feature < 0)
-               return 0;
-       substr = feature ? "(ro)" : " ";
+       substr = (device->features & DASD_FEATURE_READONLY) ? "(ro)" : " ";
        seq_printf(m, "%4s: ", substr);
        /* Print device status information. */
        switch ((device != NULL) ? device->state : -1) {