[PATCH] md: fix unchecked interruptible mutex locks

[Alexey Khoroshilov <khoroshilov@ispras.ru>]

mddev_lock() is an alias for mutex_lock_interruptible() at the moment,
but there are places where returned value of mddev_lock() is not checked.

The patch proposed introduces mddev_lock_interruptible(),
which is an equivalent for old mddev_lock(), while mddev_lock()
becomes an alias for uninterruptible mutex_lock(). 
Calls of mddev_lock(), where the result is being checked, 
are replaced by mddev_lock_interruptible().
All the other calls become uninterruptible.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
---
 drivers/md/md.c |   21 +++++++++++++--------
 1 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index b12b377..cc6d183 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -623,7 +623,12 @@ static mddev_t * mddev_find(dev_t unit)
 	goto retry;
 }

-static inline int mddev_lock(mddev_t * mddev)
+static inline void mddev_lock(mddev_t *mddev)
+{
+	return mutex_lock(&mddev->reconfig_mutex);
+}
+
+static inline int __must_check mddev_lock_interruptible(mddev_t *mddev)
 {
 	return mutex_lock_interruptible(&mddev->reconfig_mutex);
 }
@@ -2706,7 +2711,7 @@ rdev_attr_show(struct kobject *kobj, struct
attribute *attr, char *page)
 	if (!entry->show)
 		return -EIO;

-	rv = mddev ? mddev_lock(mddev) : -EBUSY;
+	rv = mddev ? mddev_lock_interruptible(mddev) : -EBUSY;
 	if (!rv) {
 		if (rdev->mddev == NULL)
 			rv = -EBUSY;
@@ -2730,7 +2735,7 @@ rdev_attr_store(struct kobject *kobj, struct
attribute *attr,
 		return -EIO;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
-	rv = mddev ? mddev_lock(mddev): -EBUSY;
+	rv = mddev ? mddev_lock_interruptible(mddev) : -EBUSY;
 	if (!rv) {
 		if (rdev->mddev == NULL)
 			rv = -EBUSY;
@@ -4199,7 +4204,7 @@ md_attr_show(struct kobject *kobj, struct
attribute *attr, char *page)

 	if (!entry->show)
 		return -EIO;
-	rv = mddev_lock(mddev);
+	rv = mddev_lock_interruptible(mddev);
 	if (!rv) {
 		rv = entry->show(mddev, page);
 		mddev_unlock(mddev);
@@ -4219,7 +4224,7 @@ md_attr_store(struct kobject *kobj, struct
attribute *attr,
 		return -EIO;
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
-	rv = mddev_lock(mddev);
+	rv = mddev_lock_interruptible(mddev);
 	if (mddev->hold_active == UNTIL_IOCTL)
 		mddev->hold_active = 0;
 	if (!rv) {
@@ -4951,7 +4956,7 @@ static void autorun_devices(int part)
 				"md: cannot allocate memory for md drive.\n");
 			break;
 		}
-		if (mddev_lock(mddev))
+		if (mddev_lock_interruptible(mddev))
 			printk(KERN_WARNING "md: %s locked, cannot run\n",
 			       mdname(mddev));
 		else if (mddev->raid_disks || mddev->major_version
@@ -5771,7 +5776,7 @@ static int md_ioctl(struct block_device *bdev,
fmode_t mode,
 		goto abort;
 	}

-	err = mddev_lock(mddev);
+	err = mddev_lock_interruptible(mddev);
 	if (err) {
 		printk(KERN_INFO
 			"md: ioctl lock interrupted, reason %d, cmd %d\n",
@@ -6379,7 +6384,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
 		return 0;
 	}

-	if (mddev_lock(mddev) < 0)
+	if (mddev_lock_interruptible(mddev) < 0)
 		return -EINTR;

 	if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
-- 1.7.1