2011-12-15 05:14:43

by Yogesh Ashok Powar

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

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 to fix the problem.

Cc: Nishant Sarmukadam <[email protected]>
Reported-by: Johannes Berg <[email protected]>
Signed-off-by: Yogesh Ashok Powar <[email protected]>
---
net/mac80211/sta_info.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index c6ca9bd..c2d4810 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -960,9 +960,9 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
* http://thread.gmane.org/gmane.linux.kernel.wireless.general/81936
*/
for (i = 0; i < STA_TID_NUM; i++) {
- if (!sta->ampdu_mlme.tid_tx[i])
+ tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[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 "
--
1.5.4.1

2011-12-15 08:23:48

by Johannes Berg

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

On Thu, 2011-12-15 at 10:43 +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 to fix the problem.

That doesn't fix any problem. It trades the compiler warning for a
runtime warning, so NACK.

You will need something like rcu_dereference_protected() here (although
it's not actually protected, but there's also no need to)

johannes