linux-kernel - [ 02/36] rtlwifi: Fix scheduling while atomic bug

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Message-Id: <20130212203857.595778754@linuxfoundation.org>
Date:	Tue, 12 Feb 2013 12:40:56 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Larry Finger <Larry.Finger@...inger.net>,
	Nathaniel Doherty <ntdoherty@...il.com>,
	Stanislaw Gruszka <sgruszka@...hat.com>,
	"John W. Linville" <linville@...driver.com>
Subject: [ 02/36] rtlwifi: Fix scheduling while atomic bug

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Larry Finger <Larry.Finger@...inger.net>

commit a5ffbe0a1993a27072742ef7db6cf9839956fce9 upstream.

Kernel commits 41affd5 and 6539306 changed the locking in rtl_lps_leave()
from a spinlock to a mutex by doing the calls indirectly from a work queue
to reduce the time that interrupts were disabled. This change was fine for
most systems; however a scheduling while atomic bug was reported in
https://bugzilla.redhat.com/show_bug.cgi?id=903881. The backtrace indicates
that routine rtl_is_special(), which calls rtl_lps_leave() in three places
was entered in atomic context. These direct calls are replaced by putting a
request on the appropriate work queue.

Signed-off-by: Larry Finger <Larry.Finger@...inger.net>
Reported-and-tested-by: Nathaniel Doherty <ntdoherty@...il.com>
Cc: Nathaniel Doherty <ntdoherty@...il.com>
Cc: Stanislaw Gruszka <sgruszka@...hat.com>
Signed-off-by: John W. Linville <linville@...driver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/rtlwifi/base.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/net/wireless/rtlwifi/base.c
+++ b/drivers/net/wireless/rtlwifi/base.c
@@ -980,7 +980,8 @@ u8 rtl_is_special_data(struct ieee80211_
 					 is_tx ? "Tx" : "Rx");

 				if (is_tx) {
-					rtl_lps_leave(hw);
+					schedule_work(&rtlpriv->
+						      works.lps_leave_work);
 					ppsc->last_delaylps_stamp_jiffies =
 					    jiffies;
 				}
@@ -990,7 +991,7 @@ u8 rtl_is_special_data(struct ieee80211_
 		}
 	} else if (ETH_P_ARP == ether_type) {
 		if (is_tx) {
-			rtl_lps_leave(hw);
+			schedule_work(&rtlpriv->works.lps_leave_work);
 			ppsc->last_delaylps_stamp_jiffies = jiffies;
 		}

@@ -1000,7 +1001,7 @@ u8 rtl_is_special_data(struct ieee80211_
 			 "802.1X %s EAPOL pkt!!\n", is_tx ? "Tx" : "Rx");

 		if (is_tx) {
-			rtl_lps_leave(hw);
+			schedule_work(&rtlpriv->works.lps_leave_work);
 			ppsc->last_delaylps_stamp_jiffies = jiffies;
 		}

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