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Subject[patch 12/38] atl1c: Fix work event interrupt/task races
2.6.38-stable review patch.  If anyone has any objections, please let us know.

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

From: Tim Gardner <timg@tpi.com>

commit cb771838715b1c470bc5735bdae709b33b18e0ad upstream.

The mechanism used to initiate work events from the interrupt
handler has a classic read/modify/write race between the interrupt
handler that sets the condition, and the worker task that reads and
clears the condition. Close these races by using atomic
bit fields.

Cc: Jie Yang <jie.yang@atheros.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/net/atl1c/atl1c.h | 6 +++---
drivers/net/atl1c/atl1c_main.c | 14 +++++---------
2 files changed, 8 insertions(+), 12 deletions(-)

--- a/drivers/net/atl1c/atl1c.h
+++ b/drivers/net/atl1c/atl1c.h
@@ -566,9 +566,9 @@ struct atl1c_adapter {
#define __AT_TESTING 0x0001
#define __AT_RESETTING 0x0002
#define __AT_DOWN 0x0003
- u8 work_event;
-#define ATL1C_WORK_EVENT_RESET 0x01
-#define ATL1C_WORK_EVENT_LINK_CHANGE 0x02
+ unsigned long work_event;
+#define ATL1C_WORK_EVENT_RESET 0
+#define ATL1C_WORK_EVENT_LINK_CHANGE 1
u32 msg_enable;

bool have_msi;
--- a/drivers/net/atl1c/atl1c_main.c
+++ b/drivers/net/atl1c/atl1c_main.c
@@ -325,7 +325,7 @@ static void atl1c_link_chg_event(struct
}
}

- adapter->work_event |= ATL1C_WORK_EVENT_LINK_CHANGE;
+ set_bit(ATL1C_WORK_EVENT_LINK_CHANGE, &adapter->work_event);
schedule_work(&adapter->common_task);
}

@@ -337,20 +337,16 @@ static void atl1c_common_task(struct wor
adapter = container_of(work, struct atl1c_adapter, common_task);
netdev = adapter->netdev;

- if (adapter->work_event & ATL1C_WORK_EVENT_RESET) {
- adapter->work_event &= ~ATL1C_WORK_EVENT_RESET;
+ if (test_and_clear_bit(ATL1C_WORK_EVENT_RESET, &adapter->work_event)) {
netif_device_detach(netdev);
atl1c_down(adapter);
atl1c_up(adapter);
netif_device_attach(netdev);
- return;
}

- if (adapter->work_event & ATL1C_WORK_EVENT_LINK_CHANGE) {
- adapter->work_event &= ~ATL1C_WORK_EVENT_LINK_CHANGE;
+ if (test_and_clear_bit(ATL1C_WORK_EVENT_LINK_CHANGE,
+ &adapter->work_event))
atl1c_check_link_status(adapter);
- }
- return;
}


@@ -369,7 +365,7 @@ static void atl1c_tx_timeout(struct net_
struct atl1c_adapter *adapter = netdev_priv(netdev);

/* Do the reset outside of interrupt context */
- adapter->work_event |= ATL1C_WORK_EVENT_RESET;
+ set_bit(ATL1C_WORK_EVENT_RESET, &adapter->work_event);
schedule_work(&adapter->common_task);
}




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