linux-kernel - Re: [PATCH] rts5208: Fix a sleep-in-atomic bug in rtsx_exclusive_enter

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Date:   Mon, 05 Jun 2017 09:05:21 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     wporter82@...il.com, sergio.paracuellos@...il.com,
        aquannie@...il.com, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rts5208: Fix a sleep-in-atomic bug in rtsx_exclusive_enter_ss

On 06/03/2017 04:52 PM, Greg KH wrote:
> On Thu, Jun 01, 2017 at 11:43:35AM +0800, Jia-Ju Bai wrote:
>> The driver may sleep under a spin lock, and the function call path is:
>> rtsx_exclusive_enter_ss (acquire the lock by spin_lock)
>>    rtsx_enter_ss
>>      rtsx_power_off_card
>>        sd_cleanup_work
>>          sd_stop_seq_mode
>>            sd_switch_clock
>>              sd_ddr_tuning
>>                sd_ddr_pre_tuning_tx
>>                  sd_change_phase
>>                    wait_timeout
>>                      schedule_timeout -->  may sleep
>>
>> To fix it, "wait_timeout" is replaced with mdelay in sd_change_phase.
> Nice work, how are you finding these bugs?  What tools gives you this
> kind of analysis?
>
> thanks,
>
> greg k-h
Hi,

I am very glad to get your praise on my work :)
I recently write a static analysis tool for detecting sleep-in-atomic 
bugs, instead of using existing tools. One reason is that I have 
encountered these bugs for some times when I writing drivers.
I am still improving my tool and detecting other similar bugs in Linux 
kernel. If you have suggestions or comments on my work, please feel free 
to contact me :)

Thanks,
Jia-Ju Bai