[PATCH V2] mac80211: Fixing sparse warning at sta_info.c

[PATCH V2] mac80211: Fixing sparse warning at sta_info.c

[Yogesh Ashok Powar]

The commit 42624d4913a00219a8fdbb4bafd634d1d843be85
created following sparse warning
>net/mac80211/sta_info.c:965:24: warning: incorrect type in assignment (different address spaces)
>net/mac80211/sta_info.c:965:24:    expected struct tid_ampdu_tx *tid_tx
>net/mac80211/sta_info.c:965:24:    got struct tid_ampdu_tx [noderef] <asn:4>*<noident>

Making use of rcu_dereference_protected to fix the problem.

V2:
 - Replacing rcu_dereference with rcu_dereference_protected
   as suggested by Johannes.
 - Adding mutex_lock/unlock to satisfy the condition at
   rcu_dereference_protected

Cc: Nishant Sarmukadam <nishants@marvell.com>
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
---
 net/mac80211/sta_info.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index c6ca9bd..e4307b7 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -959,10 +959,13 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
 	 * until the aggregation stop completes. Refer
 	 * http://thread.gmane.org/gmane.linux.kernel.wireless.general/81936
 	 */
+
+	mutex_lock(&sta->ampdu_mlme.mtx);
+
 	for (i = 0; i < STA_TID_NUM; i++) {
-		if (!sta->ampdu_mlme.tid_tx[i])
+		tid_tx = rcu_dereference_protected_tid_tx(sta, i);
+		if (!tid_tx)
 			continue;
-		tid_tx = sta->ampdu_mlme.tid_tx[i];
 		if (skb_queue_len(&tid_tx->pending)) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 			wiphy_debug(local->hw.wiphy, "TX A-MPDU  purging %d "
@@ -974,6 +977,8 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
 		kfree_rcu(tid_tx, rcu_head);
 	}
 
+	mutex_unlock(&sta->ampdu_mlme.mtx);
+
 	__sta_info_free(local, sta);
 
 	return 0;
-- 
1.7.5.4

Re: [PATCH V2] mac80211: Fixing sparse warning at sta_info.c

[John W. Linville]

Applying: mac80211: Fixing sparse warning at sta_info.c
error: patch failed: net/mac80211/sta_info.c:974
error: net/mac80211/sta_info.c: patch does not apply

What tree did you use as a base for your patch?

On Fri, Dec 16, 2011 at 11:47:15AM +0530, Yogesh Ashok Powar wrote:
> The commit 42624d4913a00219a8fdbb4bafd634d1d843be85
> created following sparse warning
> >net/mac80211/sta_info.c:965:24: warning: incorrect type in assignment (different address spaces)
> >net/mac80211/sta_info.c:965:24:    expected struct tid_ampdu_tx *tid_tx
> >net/mac80211/sta_info.c:965:24:    got struct tid_ampdu_tx [noderef] <asn:4>*<noident>
> 
> Making use of rcu_dereference_protected to fix the problem.
> 
> V2:
>  - Replacing rcu_dereference with rcu_dereference_protected
>    as suggested by Johannes.
>  - Adding mutex_lock/unlock to satisfy the condition at
>    rcu_dereference_protected
> 
> Cc: Nishant Sarmukadam <nishants@marvell.com>
> Reported-by: Johannes Berg <johannes@sipsolutions.net>
> Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
> ---
>  net/mac80211/sta_info.c |    9 +++++++--
>  1 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
> index c6ca9bd..e4307b7 100644
> --- a/net/mac80211/sta_info.c
> +++ b/net/mac80211/sta_info.c
> @@ -959,10 +959,13 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
>  	 * until the aggregation stop completes. Refer
>  	 * http://thread.gmane.org/gmane.linux.kernel.wireless.general/81936
>  	 */
> +
> +	mutex_lock(&sta->ampdu_mlme.mtx);
> +
>  	for (i = 0; i < STA_TID_NUM; i++) {
> -		if (!sta->ampdu_mlme.tid_tx[i])
> +		tid_tx = rcu_dereference_protected_tid_tx(sta, i);
> +		if (!tid_tx)
>  			continue;
> -		tid_tx = sta->ampdu_mlme.tid_tx[i];
>  		if (skb_queue_len(&tid_tx->pending)) {
>  #ifdef CONFIG_MAC80211_HT_DEBUG
>  			wiphy_debug(local->hw.wiphy, "TX A-MPDU  purging %d "
> @@ -974,6 +977,8 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
>  		kfree_rcu(tid_tx, rcu_head);
>  	}
>  
> +	mutex_unlock(&sta->ampdu_mlme.mtx);
> +
>  	__sta_info_free(local, sta);
>  
>  	return 0;
> -- 
> 1.7.5.4
> 
> --
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> 

-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

Re: [PATCH V2] mac80211: Fixing sparse warning at sta_info.c

[John W. Linville]

On Mon, Dec 19, 2011 at 02:39:57PM -0500, John W. Linville wrote:
> Applying: mac80211: Fixing sparse warning at sta_info.c
> error: patch failed: net/mac80211/sta_info.c:974
> error: net/mac80211/sta_info.c: patch does not apply
> 
> What tree did you use as a base for your patch?

NM -- it was simple to fix-up, even if 'git apply' couldn't figure
it out...

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.