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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <266eae62-bef2-6c51-415f-cbacc1669e30@redhat.com>
Date:   Wed, 14 Mar 2018 13:27:41 -0400
From:   Jonathan Toppins <jtoppins@...hat.com>
To:     Michael Chan <michael.chan@...adcom.com>
Cc:     Netdev <netdev@...r.kernel.org>,
        Andy Gospodarek <andy@...yhouse.net>,
        Siva Reddy Kallam <siva.kallam@...adcom.com>,
        Prashant Sreedharan <prashant@...adcom.com>,
        Michael Chan <mchan@...adcom.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] tg3: prevent scheduling while atomic splat

On 03/14/2018 01:22 PM, Michael Chan wrote:
> On Wed, Mar 14, 2018 at 9:36 AM, Jonathan Toppins <jtoppins@...hat.com> 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@...hat.com>
>> ---
>>
>> 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. :-)