From: bbhatt@codeaurora.org
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: manivannan.sadhasivam@linaro.org, hemantk@codeaurora.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
jhugo@codeaurora.org, sdias@codeaurora.org,
linux-arm-msm@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: bus/mhi/core: Double lock in mhi_device_put() and dev_wake inc/dec
Date: Fri, 18 Sep 2020 19:34:10 -0700 [thread overview]
Message-ID: <05ea5c258f0b3b2bf9a8fdc54500259f@codeaurora.org> (raw)
In-Reply-To: <5029d4b5-d614-eef3-5a7a-9c8e1c3e7ddb@linuxfoundation.org>
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'
prev parent reply other threads:[~2020-09-19 2:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-17 23:16 bus/mhi/core: Double lock in mhi_device_put() and dev_wake inc/dec Shuah Khan
2020-09-19 2:34 ` bbhatt [this message]
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