2013-02-02 21:55:04

by Larry Finger

[permalink] [raw]
Subject: [PATCH] rtlwifi: Fix scheduling while atomic bug

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 <[email protected]>
Reported-and-tested-by: Nathaniel Doherty <[email protected]>
Cc: Nathaniel Doherty <[email protected]>
Cc: Stanislaw Gruszka <[email protected]>
Cc: Stable <[email protected]>
---

John,

If DaveM will still accept bug fixes for 3.8, please push this one. It
is unlikely to have any side effects.

Thanks,

Larry
---

base.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

Index: wireless-testing-new/drivers/net/wireless/rtlwifi/base.c
===================================================================
--- wireless-testing-new.orig/drivers/net/wireless/rtlwifi/base.c
+++ wireless-testing-new/drivers/net/wireless/rtlwifi/base.c
@@ -1004,7 +1004,8 @@ 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;
}
@@ -1014,7 +1015,7 @@ 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;
}

@@ -1024,7 +1025,7 @@ 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;
}