| From b4f37168f2d6523b0465f0f943ebb307b3ea64d1 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 14 Sep 2020 11:26:41 +0800 |
| Subject: uio: free uio id after uio file node is freed |
| |
| 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.com |
| 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 73efb80815db8..6dca744e39e95 100644 |
| --- a/drivers/uio/uio.c |
| +++ b/drivers/uio/uio.c |
| @@ -1048,8 +1048,6 @@ 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); |
| |
| @@ -1064,6 +1062,8 @@ void uio_unregister_device(struct uio_info *info) |
| |
| device_unregister(&idev->dev); |
| |
| + uio_free_minor(idev); |
| + |
| return; |
| } |
| EXPORT_SYMBOL_GPL(uio_unregister_device); |
| -- |
| 2.27.0 |
| |