Re: [PATCH net] tg3: prevent scheduling while atomic splat

[Jonathan Toppins]

On 03/14/2018 01:22 PM, Michael Chan wrote:
> On Wed, Mar 14, 2018 at 9:36 AM, Jonathan Toppins <jtoppins@xxxxxxxxxx> wrote:
>> The problem was introduced in commit
>> 506b0a395f26 ("[netdrv] tg3: APE heartbeat changes"). The bug occurs
>> because tp->lock spinlock is held which is obtained in tg3_start
>> by way of tg3_full_lock(), line 11571. The documentation for usleep_range()
>> specifically states it cannot be used inside a spinlock.
>>
>> Fixes: 506b0a395f26 ("[netdrv] tg3: APE heartbeat changes")
>> Signed-off-by: Jonathan Toppins <jtoppins@xxxxxxxxxx>
>> ---
>>
>> Notes:
>>     The thing I need reviewed from Broadcom is if the udelay should be 20
>>     instead of 10, due to any timing changes introduced by the offending
>>     patch.
> 
> Thanks.  10 us is correct.
> 
> As a future improvement, we might want to see if we can release the
> spinlock and go back to usleep_range().  The wait time is potentially
> up to 20 msec which is quite long.

Agreed, glad it is not just me wondering why a lock needs to be held for
reads. :-)