From: Peter Hurley <peter@hurleysoftware.com>
To: Alexander Aring <alex.aring@gmail.com>
Cc: Jukka Rissanen <jukka.rissanen@linux.intel.com>,
linux-bluetooth@vger.kernel.org
Subject: Re: [PATCH] Bluetooth: Incorrect locking when sending data in softirq
Date: Wed, 15 Oct 2014 17:58:40 -0400 [thread overview]
Message-ID: <543EEE10.2010000@hurleysoftware.com> (raw)
In-Reply-To: <20141015215324.GB17138@omega>
On 10/15/2014 05:53 PM, Alexander Aring wrote:
> Hi Peter,
>
> On Wed, Oct 15, 2014 at 04:46:24PM -0400, Peter Hurley wrote:
> ...
>>
>> That's happening because 6lowpan.c:send_mcast_pkt() is disabling
>> interrupts with the read_lock_irqsave() before calling send_pkt().
>>
>> It's unclear browsing through the lowpan driver why the
>> irqflags save/restore read_lock flavors are being used; is there a
>> place where the bluetooth core is calling the driver in atomic
>> context (ie., where interrupts are disabled)?
>>
>
> In my opinion bt_xmit is called in atomic context. Make the stacktrace
> sense now?
I don't think so.
The network layer is very careful about keeping interrupts enabled
and calling network drivers from softirq, so that spin_lock_bh() is
typically all that's required.
> It's the callback 'ndo_start_xmit' of 'struct net_device_ops' [0].
The send_mcast_pkt() isn't showing in the stack trace because it's
being inlined; and send_mcast_pkt() is definitely disabling interrupts
and calling send_pkt().
Regards,
Peter Hurley
next prev parent reply other threads:[~2014-10-15 21:58 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-15 12:43 [PATCH] Bluetooth: Incorrect locking when sending data in softirq Jukka Rissanen
2014-10-15 13:18 ` Peter Hurley
2014-10-15 13:32 ` Jukka Rissanen
2014-10-15 20:46 ` Peter Hurley
2014-10-15 21:53 ` Alexander Aring
2014-10-15 21:58 ` Peter Hurley [this message]
2014-10-15 22:23 ` Alexander Aring
2014-10-16 1:20 ` Peter Hurley
2014-10-16 7:47 ` Jukka Rissanen
2014-10-15 13:36 ` Alexander Aring
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