We do not check whether we already registered a CUSE device with a given name so we might end up with two devices with the same name. Sysfs will then complain as it cannot create suitable directories.
This patch makes the init-command fail if there is already a device with the given name. To avoid race-conditions, we protect the whole registration with a mutex now. Following the sysfs warnings when registering two devices with the same name: ------------[ cut here ]------------ WARNING: at fs/sysfs/dir.c:529 sysfs_add_one+0xc8/0xf0() Hardware name: N150P/N210P/N220P sysfs: cannot create duplicate filename '/devices/virtual/cuse/ttyFseat0' Modules linked in: btusb bluetooth Pid: 14089, comm: lt-kmscon Tainted: G W 3.5.3+ #60 Call Trace: [<ffffffff81136400>] ? sysfs_add_one+0x60/0xf0 [<ffffffff8102f99d>] warn_slowpath_common+0x7d/0xc0 [<ffffffff8102fa83>] warn_slowpath_fmt+0x43/0x50 [<ffffffff81136468>] sysfs_add_one+0xc8/0xf0 [<ffffffff81136686>] create_dir+0x76/0xd0 [<ffffffff81136a14>] sysfs_create_dir+0x84/0xe0 [<ffffffff811fe67b>] kobject_add_internal+0x9b/0x200 [<ffffffff811feb38>] kobject_add+0x68/0xc0 [<ffffffff81310c73>] device_add+0xe3/0x680 [<ffffffff8130f5ae>] ? dev_set_name+0x3e/0x40 [<ffffffff811c6834>] cuse_process_init_reply+0x204/0x410 [<ffffffff811c6630>] ? cuse_open+0xe0/0xe0 [<ffffffff811bb23c>] request_end+0xfc/0x1a0 [<ffffffff811bc6e2>] fuse_dev_do_write+0xa32/0xd10 [<ffffffff811ba435>] ? fuse_copy_one+0x45/0x60 [<ffffffff8109cf06>] ? find_get_page+0x66/0xb0 [<ffffffff811bccc0>] ? fuse_dev_splice_write+0x300/0x300 [<ffffffff811bcd29>] fuse_dev_write+0x69/0x80 [<ffffffff810d569c>] do_sync_readv_writev+0xdc/0x120 [<ffffffff810d57db>] ? rw_copy_check_uvector+0x6b/0x130 [<ffffffff810b9c5e>] ? handle_mm_fault+0x12e/0x1f0 [<ffffffff810d5973>] do_readv_writev+0xd3/0x1e0 [<ffffffff810d5ab0>] vfs_writev+0x30/0x60 [<ffffffff810d5c38>] sys_writev+0x48/0xb0 [<ffffffff815846a2>] system_call_fastpath+0x16/0x1b ---[ end trace 368eb04507b14c94 ]--- Signed-off-by: David Herrmann <[email protected]> --- Hi again I changed the spinlock to a mutex now. This should make it more readable as Tejun suggested. Thanks David fs/fuse/cuse.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index 1326051..3f392e9 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 @@ struct cuse_conn { 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; @@ -117,14 +116,18 @@ static int cuse_open(struct inode *inode, struct file *file) int rc; /* look up and get the connection */ - spin_lock(&cuse_lock); + rc = mutex_lock_interruptible(&cuse_lock); + if (rc) + return rc; + 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) @@ -308,7 +311,7 @@ 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 = { }; @@ -359,15 +362,23 @@ 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 */ + list_for_each_entry(pos, cuse_conntbl_head(devt), 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; @@ -380,9 +391,9 @@ static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req) cc->cdev = cdev; /* make the device available */ - spin_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); @@ -394,7 +405,8 @@ out: err_cdev: cdev_del(cdev); -err_device: +err_unlock: + mutex_unlock(&cuse_lock); put_device(dev); err_region: unregister_chrdev_region(devt, 1); @@ -524,9 +536,9 @@ static int cuse_channel_release(struct inode *inode, struct file *file) 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) -- 1.8.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
