Messages in this thread | | | Date | Fri, 18 Sep 2020 19:34:10 -0700 | From | bbhatt@codeauro ... | Subject | Re: bus/mhi/core: Double lock in mhi_device_put() and dev_wake inc/dec |
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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'
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