From: Lang Dai lang.dai@intel.com
[ Upstream commit 8fd0e2a6df262539eaa28b0a2364cca10d1dc662 ]
uio_register_device() do two things. 1) get an uio id from a global pool, e.g. the id is <A> 2) create file nodes like /sys/class/uio/uio<A>
uio_unregister_device() do two things. 1) free the uio id <A> and return it to the global pool 2) free the file node /sys/class/uio/uio<A>
There is a situation is that one worker is calling uio_unregister_device(), and another worker is calling uio_register_device(). If the two workers are X and Y, they go as below sequence, 1) X free the uio id <AAA> 2) Y get an uio id <AAA> 3) Y create file node /sys/class/uio/uio<AAA> 4) X free the file note /sys/class/uio/uio<AAA> Then it will failed at the 3rd step and cause the phenomenon we saw as it is creating a duplicated file node.
Failure reports as follows: sysfs: cannot create duplicate filename '/class/uio/uio10' Call Trace: sysfs_do_create_link_sd.isra.2+0x9e/0xb0 sysfs_create_link+0x25/0x40 device_add+0x2c4/0x640 __uio_register_device+0x1c5/0x576 [uio] adf_uio_init_bundle_dev+0x231/0x280 [intel_qat] adf_uio_register+0x1c0/0x340 [intel_qat] adf_dev_start+0x202/0x370 [intel_qat] adf_dev_start_async+0x40/0xa0 [intel_qat] process_one_work+0x14d/0x410 worker_thread+0x4b/0x460 kthread+0x105/0x140 ? process_one_work+0x410/0x410 ? kthread_bind+0x40/0x40 ret_from_fork+0x1f/0x40 Code: 85 c0 48 89 c3 74 12 b9 00 10 00 00 48 89 c2 31 f6 4c 89 ef e8 ec c4 ff ff 4c 89 e2 48 89 de 48 c7 c7 e8 b4 ee b4 e8 6a d4 d7 ff <0f> 0b 48 89 df e8 20 fa f3 ff 5b 41 5c 41 5d 5d c3 66 0f 1f 84 ---[ end trace a7531c1ed5269e84 ]--- c6xxvf b002:00:00.0: Failed to register UIO devices c6xxvf b002:00:00.0: Failed to register UIO devices
Signed-off-by: Lang Dai lang.dai@intel.com
Link: https://lore.kernel.org/r/1600054002-17722-1-git-send-email-lang.dai@intel.c... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/uio/uio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index a57698985f9c4..8313f81968d51 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -1010,8 +1010,6 @@ void uio_unregister_device(struct uio_info *info)
idev = info->uio_dev;
- uio_free_minor(idev); - mutex_lock(&idev->info_lock); uio_dev_del_attributes(idev);
@@ -1026,6 +1024,8 @@ void uio_unregister_device(struct uio_info *info)
device_unregister(&idev->dev);
+ uio_free_minor(idev); + return; } EXPORT_SYMBOL_GPL(uio_unregister_device);