Re: [PATCH net-next 2/5] tipc: Simplify bearer shutdown logic

[Neil Horman <nhorman@tuxdriver.com>]

On Thu, Oct 14, 2010 at 07:58:26PM -0400, Paul Gortmaker wrote:
> [Re: [PATCH net-next 2/5] tipc: Simplify bearer shutdown logic] On 13/10/2010 (Wed 10:39) Neil Horman wrote:
> 
> > On Tue, Oct 12, 2010 at 08:25:55PM -0400, Paul Gortmaker wrote:
> > > From: Allan Stephens <allan.stephens@windriver.com>
> > > 
> > > Disable all active bearers when TIPC is shut down without having to do
> > > a name-based search to locate each bearer object.
> > > 
> > It seems like you're doing a good deal more in this patch than just disabling
> > all active bearers without doing a name search.  The description is implemented
> > in the for loop of tipc_bearer_stop.  Whats the rest of it for?
> 
> It seems the original needlessly bloated out the patch size by
> swapping the order of tipc_bearer_find_interface & bearer_find
> in the file (now fixed) - and you are right, the locking change
> wasn't properly covered in the commit log.  The extra test you'd
> suggested tossing out is also now gone.
> 
> This change doesn't explicitly depend on any other changes,
> so if it is now OK, the option is there for it to be applied
> independently of the others that haven't been reworked yet.
> 
> Thanks,
> Paul.
> 
> 
> From 1771ad642cb076dbeb71e3533a25cb2f07df9cd8 Mon Sep 17 00:00:00 2001
> From: Allan Stephens <allan.stephens@windriver.com>
> Date: Sat, 4 Sep 2010 09:29:04 -0400
> Subject: [PATCH] tipc: Simplify bearer shutdown logic
> 
> Optimize processing in TIPC's bearer shutdown code, including:
> 
> 1. Remove an unnecessary check to see if TIPC bearer's can exist.
> 2. Don't release spinlocks before calling a media-specific disabling
> routine, since the routine can't sleep.
> 3. Make bearer_disable() operate directly on a struct bearer, instead
> of needlessly taking a name and then mapping that to the struct.
> 
> Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> ---
>  net/tipc/bearer.c |   38 +++++++++++---------------------------
>  1 files changed, 11 insertions(+), 27 deletions(-)
> 
> diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
> index 9c10c6b..fd9c06c 100644
> --- a/net/tipc/bearer.c
> +++ b/net/tipc/bearer.c
> @@ -288,9 +288,6 @@ static struct bearer *bearer_find(const char *name)
>  	struct bearer *b_ptr;
>  	u32 i;
>  
> -	if (tipc_mode != TIPC_NET_MODE)
> -		return NULL;
> -
>  	for (i = 0, b_ptr = tipc_bearers; i < MAX_BEARERS; i++, b_ptr++) {
>  		if (b_ptr->active && (!strcmp(b_ptr->publ.name, name)))
>  			return b_ptr;
> @@ -630,30 +627,17 @@ int tipc_block_bearer(const char *name)
>   * Note: This routine assumes caller holds tipc_net_lock.
>   */
>  
> -static int bearer_disable(const char *name)
> +static int bearer_disable(struct bearer *b_ptr)
>  {
> -	struct bearer *b_ptr;
>  	struct link *l_ptr;
>  	struct link *temp_l_ptr;
>  
> -	b_ptr = bearer_find(name);
> -	if (!b_ptr) {
> -		warn("Attempt to disable unknown bearer <%s>\n", name);
> -		return -EINVAL;
> -	}
> -
> -	info("Disabling bearer <%s>\n", name);
> +	info("Disabling bearer <%s>\n", b_ptr->publ.name);
>  	tipc_disc_stop_link_req(b_ptr->link_req);
>  	spin_lock_bh(&b_ptr->publ.lock);
>  	b_ptr->link_req = NULL;
>  	b_ptr->publ.blocked = 1;
> -	if (b_ptr->media->disable_bearer) {
> -		spin_unlock_bh(&b_ptr->publ.lock);
> -		write_unlock_bh(&tipc_net_lock);
> -		b_ptr->media->disable_bearer(&b_ptr->publ);
> -		write_lock_bh(&tipc_net_lock);
> -		spin_lock_bh(&b_ptr->publ.lock);
> -	}
> +	b_ptr->media->disable_bearer(&b_ptr->publ);
>  	list_for_each_entry_safe(l_ptr, temp_l_ptr, &b_ptr->links, link_list) {
>  		tipc_link_delete(l_ptr);
>  	}
> @@ -664,10 +648,16 @@ static int bearer_disable(const char *name)
>  
>  int tipc_disable_bearer(const char *name)
>  {
> +	struct bearer *b_ptr;
>  	int res;
>  
>  	write_lock_bh(&tipc_net_lock);
> -	res = bearer_disable(name);
> +	b_ptr = bearer_find(name);
> +	if (b_ptr == NULL) {
> +		warn("Attempt to disable unknown bearer <%s>\n", name);
> +		res = -EINVAL;
> +	} else
> +		res = bearer_disable(b_ptr);
>  	write_unlock_bh(&tipc_net_lock);
>  	return res;
>  }
> @@ -680,13 +670,7 @@ void tipc_bearer_stop(void)
>  
>  	for (i = 0; i < MAX_BEARERS; i++) {
>  		if (tipc_bearers[i].active)
> -			tipc_bearers[i].publ.blocked = 1;
> -	}
> -	for (i = 0; i < MAX_BEARERS; i++) {
> -		if (tipc_bearers[i].active)
> -			bearer_disable(tipc_bearers[i].publ.name);
> +			bearer_disable(&tipc_bearers[i]);
>  	}
>  	media_count = 0;
>  }
> -
> -
> -- 
> 1.7.2.1
> 
> 

Yes, this looks much better, thank you.
Reviewed-by: Neil Horman <nhorman@tuxdriver.com>