netdev - Re: [PATCH] d80211: Fix inconsistent sta

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Message-ID: <a32f33a40701020730n773d7ed8pe99d98ecc7b96a0e@mail.gmail.com>
Date:	Tue, 2 Jan 2007 16:30:41 +0100
From:	"Ivo Van Doorn" <ivdoorn@...il.com>
To:	"Jan Kiszka" <jan.kiszka@....de>
Cc:	"Jiri Benc" <jbenc@...e.cz>, netdev@...r.kernel.org,
	rt2400-devel@...ts.sourceforge.net
Subject: Re: [PATCH] d80211: Fix inconsistent sta_lock usage

On 1/1/07, Jan Kiszka <jan.kiszka@....de> wrote:
> Hacking a bit on rt2x00 to make it work in master and ad-hoc mode, lockdep
> popped up on some hostapd ioctls, pointing out remaining inconsistencies
> related to sta_lock:
>
> 1. sta_lock holders must always be protected against softirq
> 2. bss_tim_set/clear must not be called with sta_lock held, rather an
>    unprotected variant
> 3. ieee80211_ioctl_remove_sta is not already holding the lock when calling
>    sta_info_free
>
> As I was not sure if sta_info_remove_aid_ptr needs lock protection or
> not, I played safe and moved it always under the lock. Please correct me
> if this is overkill.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@....de>
>
> [Sorry, patch is against rt2x00 CVS. I'm lacking time and bandwidth to pull
> the d80211 git repos and rebase.]

To make it easier for everybody, here is the same patch
only this time applied to the dscape git tree. ;)

Signed-off-by: Jan Kiszka <jan.kiszka@....de>
Signed-off-by: Ivo van Doorn <IvDoorn@...il.com>

---

diff --git a/net/d80211/ieee80211_i.h b/net/d80211/ieee80211_i.h
index ef303da..b132ae0 100644
--- a/net/d80211/ieee80211_i.h
+++ b/net/d80211/ieee80211_i.h
@@ -558,20 +558,32 @@ struct sta_attribute {
 	ssize_t (*store)(struct sta_info *, const char *buf, size_t count);
 };

+static inline void __bss_tim_set(struct ieee80211_local *local,
+				 struct ieee80211_if_ap *bss, int aid)
+{
+	bss->tim[(aid)/8] |= 1<<((aid) % 8);
+}
+
 static inline void bss_tim_set(struct ieee80211_local *local,
 			       struct ieee80211_if_ap *bss, int aid)
 {
-	spin_lock(&local->sta_lock);
-	bss->tim[(aid)/8] |= 1<<((aid) % 8);
-	spin_unlock(&local->sta_lock);
+	spin_lock_bh(&local->sta_lock);
+	__bss_tim_set(local, bss, aid);
+	spin_unlock_bh(&local->sta_lock);
+}
+
+static inline void __bss_tim_clear(struct ieee80211_local *local,
+				   struct ieee80211_if_ap *bss, int aid)
+{
+	bss->tim[(aid)/8] &= !(1<<((aid) % 8));
 }

 static inline void bss_tim_clear(struct ieee80211_local *local,
 				 struct ieee80211_if_ap *bss, int aid)
 {
-	spin_lock(&local->sta_lock);
-	bss->tim[(aid)/8] &= !(1<<((aid) % 8));
-	spin_unlock(&local->sta_lock);
+	spin_lock_bh(&local->sta_lock);
+	__bss_tim_clear(local, bss, aid);
+	spin_unlock_bh(&local->sta_lock);
 }

 /* ieee80211.c */
diff --git a/net/d80211/ieee80211_ioctl.c b/net/d80211/ieee80211_ioctl.c
index c74b431..1363a01 100644
--- a/net/d80211/ieee80211_ioctl.c
+++ b/net/d80211/ieee80211_ioctl.c
@@ -285,7 +285,9 @@ static int ieee80211_ioctl_add_sta(struct net_device *dev,
 	if (sta->dev != dev) {
 		/* Binding STA to a new interface, so remove all references to
 		 * the old BSS. */
+		spin_lock_bh(&local->sta_lock);
 		sta_info_remove_aid_ptr(sta);
+		spin_unlock_bh(&local->sta_lock);
 	}

         /* TODO
@@ -359,7 +361,7 @@ static int ieee80211_ioctl_remove_sta(struct
net_device *dev,
 	sta = sta_info_get(local, param->sta_addr);
 	if (sta) {
 		sta_info_put(sta);
-		sta_info_free(sta, 1);
+		sta_info_free(sta, 0);
 	}

 	return sta ? 0 : -ENOENT;
diff --git a/net/d80211/sta_info.c b/net/d80211/sta_info.c
index 0c42ae8..e120a4f 100644
--- a/net/d80211/sta_info.c
+++ b/net/d80211/sta_info.c
@@ -439,7 +439,7 @@ void sta_info_remove_aid_ptr(struct sta_info *sta)
 		sdata->local->ops->set_tim(local_to_hw(sdata->local),
 					  sta->aid, 0);
 	if (sdata->bss)
-		bss_tim_clear(sdata->local, sdata->bss, sta->aid);
+		__bss_tim_clear(sdata->local, sdata->bss, sta->aid);
 }
-
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