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cuse: do not register multiple devices with identical names 

Sysfs doesn't allow two devices with the same name, but we register a
sysfs entry for each cuse device without checking for name collisions.
This extends the registration to first check whether the name was already
registered.

To avoid race-conditions between the name-check and linking the device, we
need to protect the whole registration with a mutex.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
David Herrmann 2012-11-17 12:45:48 +01:00 committed by Miklos Szeredi
parent 8ce03fd76d
commit 30783587b0
1 changed files with 15 additions and 6 deletions
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21
fs/fuse/cuse.c
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@ -304,14 +304,14 @@ static void cuse_gendev_release(struct device *dev)
*/
static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
{
struct cuse_conn *cc = fc_to_cc(fc);
struct cuse_conn *cc = fc_to_cc(fc), *pos;
struct cuse_init_out *arg = req->out.args[0].value;
struct page *page = req->pages[0];
struct cuse_devinfo devinfo = { };
struct device *dev;
struct cdev *cdev;
dev_t devt;
int rc;
int rc, i;
if (req->out.h.error ||
arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) {
@ -355,15 +355,24 @@ static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
dev_set_drvdata(dev, cc);
dev_set_name(dev, "%s", devinfo.name);
mutex_lock(&cuse_lock);
/* make sure the device-name is unique */
for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {
list_for_each_entry(pos, &cuse_conntbl[i], list)
if (!strcmp(dev_name(pos->dev), dev_name(dev)))
goto err_unlock;
}
rc = device_add(dev);
if (rc)
goto err_device;
goto err_unlock;
/* register cdev */
rc = -ENOMEM;
cdev = cdev_alloc();
if (!cdev)
goto err_device;
goto err_unlock;
cdev->owner = THIS_MODULE;
cdev->ops = &cuse_frontend_fops;
@ -376,7 +385,6 @@ static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
cc->cdev = cdev;
/* make the device available */
mutex_lock(&cuse_lock);
list_add(&cc->list, cuse_conntbl_head(devt));
mutex_unlock(&cuse_lock);
@ -390,7 +398,8 @@ out:
err_cdev:
cdev_del(cdev);
err_device:
err_unlock:
mutex_unlock(&cuse_lock);
put_device(dev);
err_region:
unregister_chrdev_region(devt, 1);