On 2020-09-17 16:16, Shuah Khan wrote:
While looking at this file for an unrelated issue, I happen to notice
there is a double locking on mhi_cntrl->pm_lock in the mhi_device_put()
when it gets called from mhi_driver_remove()
The other two calls from mhi_driver_probe() don't hold the pm_lock.
In addition, lock holding while dev_wake updates is inconsistent.
dev_wake gets incremented and decremented without holding pm_lock in
mhi_device_get(), mhi_device_get_sync() and mhi_device_put().
Exception are when mhi_device_put() is called from mhi_driver_remove().
The following commit is where all this code is added.
bus: mhi: core: Add support for data transfer
https://github.com/torvalds/linux/commit/189ff97cca53e3fe2d8b38d64105040ce17fc62d
It appears to be real problem. I don't have a way to test this driver,
hence reaching out to let you know about my findings.
thanks,
-- Shuah
Thank you for inputs.
Hemant and I discussed this and we agree that there are inconsistencies
we need to fix.
We will be uploading a patch to remove the read_lock_bh/read_unlock_bh
calls from the
mhi_driver_remove().
Thanks,
Bhaumik
'The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum, a Linux Foundation Collaborative Project'
