Hi,
I was looking at the CDC-WDM driver. It uses cancel_work_sync()
in the pre_reset() method. I looked at the work and saw a GFP_KERNEL
there.
Now suppose a device has a wdm interface and a storage interface.
Is the following sequence possible?
kmalloc with GFP_KERNEL in the work
VM layer decides to page to storage interface
task blocks waiting for completion of IO
SCSI layer sees an error
SCSI error handling starts
SCSI layer requests a bus reset
USB layer calls pre_reset() of cdc-wdm
wdm_pre_reset() calls cancel_work_sync()
cancel_work_sync() waits for work to finish
DEADLOCK
What do you think?
Regards
Oliver
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