usb stack deadlocks after plugging in card reader

[monni]

How to reproduce:

1. Open terminal with tail -f /var/log/syslog
2. Plug usb card reader without any cards

Experienced behavior: Terminal deadlocks Expected behavior: Terminal continues to respond to mouse events

Concerning threads: 35 usb explore, holds "legacy driver", waits for "devfs lock" 158 sh, holds "devfs lock", waits for "legacy driver" 198 Terminal, waits for "devfs lock", blocks "usb explore"

First significant entries for thread 35 are: <usb>:RescanDrivers5StackP11rescan_item + 0x001b <usb>:ExploreThread5StackPv + 0x0101

Last significant entry for thread 35 is: <kernel>:publish_deviceFP5devfsPCcP10BaseDevice + 0x007a

First significant entry for thread 158 is: <kernel>:vfs_free_io_context + 0x0078

Last significant entry for thread 158 is: <kernel>:UninitDevice12LegacyDevice + 0x0028

First significant entry for thread 198 is: <kernel>:_user_open + 0x00a1

Last significant entry for thread 198 is: <kernel>:devfs_open_FP9fs_volumeP8fs_vnodeiPPv + 0x0072

I omitted functions between those because I don't think they're relevant to finding the cause and I would have to hand-copy them because I don't have serial cable here.

[mmlr]

This is a deadlock between the devfs and the legacy driver system. USB is only the trigger, not the problem itself. This was introduced with the new device manager, assigning to Axel.

[axeld]

Does this still happen?

[monni]

Hasn't happened for me lately...

[axeld]

Thanks for the quick update! There have been quite some changes in that area, so I assume it to be fixed. Please reopen if it happens again.