On Tue, Sep 08, 2020 at 08:58:53AM +0000, Dai, Lang wrote: > Hi, > > This patch is for uio to fix an error of "Failed to register UIO devices". We encountered this uio error when we tried to attached and disconnected devices to a VM many times for pressure test. > > Could you please help to review this patch and give some advices? > Thanks a lot. > > > commit 5c005f479e61a523f473b38361d2b241a24538ca > Author: Lang Dai <lang.dai@xxxxxxxxx<mailto:lang.dai@xxxxxxxxx>> > Date: Mon Sep 7 13:21:39 2020 +0800 > > UBUNTU: uio: free uio id after uio file node is freed > > 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@xxxxxxxxx<mailto:lang.dai@xxxxxxxxx>> This isn't the right way to format patches, use git format-patch and git send-email. > diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c > index 73efb80..6dca744 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); The patch itself makes sense since cleanup should be in the reverse order of initialization. However, pls fix error path in __uio_register_device to also be in the same order. Thanks! > (END) > > Best Regards, > Dai, Lang
