cuse: use mutex as registration lock instead of spinlocks
We need to check for name-collisions during cuse-device registration. To
avoid race-conditions, this needs to be protected during the whole device
registration. Therefore, replace the spinlocks by mutexes first so we can
safely extend the locked regions to include more expensive or sleeping
code paths.
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index ee8d550..048e89f 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -45,7 +45,6 @@
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/slab.h>
-#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/module.h>
@@ -63,7 +62,7 @@
bool unrestricted_ioctl;
};
-static DEFINE_SPINLOCK(cuse_lock); /* protects cuse_conntbl */
+static DEFINE_MUTEX(cuse_lock); /* protects registration */
static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN];
static struct class *cuse_class;
@@ -114,14 +113,14 @@
int rc;
/* look up and get the connection */
- spin_lock(&cuse_lock);
+ mutex_lock(&cuse_lock);
list_for_each_entry(pos, cuse_conntbl_head(devt), list)
if (pos->dev->devt == devt) {
fuse_conn_get(&pos->fc);
cc = pos;
break;
}
- spin_unlock(&cuse_lock);
+ mutex_unlock(&cuse_lock);
/* dead? */
if (!cc)
@@ -377,9 +376,9 @@
cc->cdev = cdev;
/* make the device available */
- spin_lock(&cuse_lock);
+ mutex_lock(&cuse_lock);
list_add(&cc->list, cuse_conntbl_head(devt));
- spin_unlock(&cuse_lock);
+ mutex_unlock(&cuse_lock);
/* announce device availability */
dev_set_uevent_suppress(dev, 0);
@@ -520,9 +519,9 @@
int rc;
/* remove from the conntbl, no more access from this point on */
- spin_lock(&cuse_lock);
+ mutex_lock(&cuse_lock);
list_del_init(&cc->list);
- spin_unlock(&cuse_lock);
+ mutex_unlock(&cuse_lock);
/* remove device */
if (cc->dev)