netdev - Re: [PATCH net] bridge: stp: when using userspace stp stop kernel hello and hold timers

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Message-ID: <20150723101311.5e15b970@urahara>
Date:	Thu, 23 Jul 2015 10:13:11 -0700
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Cc:	netdev@...r.kernel.org, bridge@...ts.linux-foundation.org,
	davem@...emloft.net, Satish Ashok <sashok@...ulusnetworks.com>
Subject: Re: [PATCH net] bridge: stp: when using userspace stp stop kernel
 hello and hold timers

On Thu, 23 Jul 2015 19:05:56 +0200
Nikolay Aleksandrov <nikolay@...ulusnetworks.com> wrote:

> On 07/23/2015 06:59 PM, Stephen Hemminger wrote:
> > On Thu, 23 Jul 2015 09:07:37 -0700
> > Nikolay Aleksandrov <nikolay@...ulusnetworks.com> wrote:
> >   
> >> +		/* Stop hello and hold timer */
> >> +		spin_lock_bh(&br->lock);
> >> +		del_timer(&br->hello_timer);
> >> +		list_for_each_entry(p, &br->port_list, list)
> >> +			del_timer(&p->hold_timer);
> >> +		spin_unlock_bh(&br->lock);  
> > 
> > Wouldn't it be easier to use del_timer_sync here?
> >   
> I think it should work. Also I have an error in the commit message
> about the kernel BPDU sending which I need to correct. I'll prepare
> a v2 with your suggestion and fixed commit message.

The one thing to watch out for with del_timer_sync is that
the timer routine and the caller can't be using the same lock
otherwise timer will be spinning waiting to get lock that
is held by caller who is waiting for timer.
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