[PATCH]atl1c:Do not call cancel_work_sync from the work itself

[jie.yang]

Do not call cancel_work_sync from the work itself, for it my cause 
recursive locking.
detail info:
events/1/10 is trying to acquire lock:
(&adapter->reset_task){+.+...}, at: [<c043e384>] __cancel_work_timer+0x80/0x187

but task is already holding lock:
(&adapter->reset_task){+.+...}, at: [<c043ed6f>] worker_thread+0x127/0x234
other info that might help us debug this:

2 locks held by events/1/10:
#0:  (events){+.+.+.}, at: [<c043ed6f>] worker_thread+0x127/0x234
#1:  (&adapter->reset_task){+.+...}, at: [<c043ed6f>] worker_thread+0x127/0x234

stack backtrace:
Pid: 10, comm: events/1 Not tainted 2.6.31-rc2 #12
Call Trace:
[<c04519c9>] validate_chain+0x4ae/0xb26
[<c0451e8d>] ? validate_chain+0x972/0xb26
[<c0437f4b>] ? lock_timer_base+0x1f/0x3e
[<c04526f8>] __lock_acquire+0x6b7/0x745
[<c0452816>] lock_acquire+0x90/0xad
[<c043e384>] ? __cancel_work_timer+0x80/0x187
[<c043e3b1>] __cancel_work_timer+0xad/0x187
[<c043e384>] ? __cancel_work_timer+0x80/0x187
[<c044f6b3>] ? mark_held_locks+0x3d/0x58
[<c0690855>] ? _spin_unlock_irqrestore+0x36/0x3c
[<c044f7d5>] ? trace_hardirqs_on_caller+0x107/0x12f
[<c044f808>] ? trace_hardirqs_on+0xb/0xd
[<c0437fb2>] ? try_to_del_timer_sync+0x48/0x4f
[<c043e4a2>] cancel_work_sync+0xa/0xc
[<f8955f95>] atl1c_down+0x1f/0xde [atl1c]
[<f8956955>] atl1c_reset_task+0x1f/0x31 [atl1c]
[<c043edae>] worker_thread+0x166/0x234
[<c043ed6f>] ? worker_thread+0x127/0x234
[<f8956936>] ? atl1c_reset_task+0x0/0x31 [atl1c]
[<c0441ac5>] ? autoremove_wake_function+0x0/0x33
[<c043ec48>] ? worker_thread+0x0/0x234
[<c0441a25>] kthread+0x69/0x70
[<c04419bc>] ? kthread+0x0/0x70
[<c04034b7>] kernel_thread_helper+0x7/0x10

So when atl1c_reset_task be scheduled just set a flag in ctrl_flag, 
to demonstrate it is in reset_task, when atl1c_down is call it will not call 
cancel_work_sync(&adapter->reset_task) if it sees the flag.

Signed-off-by: jie yang <jie.yang@xxxxxxxxxxx>
---
diff --git a/drivers/net/atl1c/atl1c.h b/drivers/net/atl1c/atl1c.h
index 2a1120a..53242dc 100644
--- a/drivers/net/atl1c/atl1c.h
+++ b/drivers/net/atl1c/atl1c.h
@@ -427,6 +427,7 @@ struct atl1c_hw {
 #define ATL1C_ASPM_CTRL_MON        0x0200
 #define ATL1C_HIB_DISABLE      0x0400
 #define ATL1C_LINK_CAP_1000M       0x0800
+#define ATL1C_RESET_IN_WORK        0x1000
 #define ATL1C_FPGA_VERSION     0x8000
    u16 cmb_tpd;
    u16 cmb_rrd;
diff --git a/drivers/net/atl1c/atl1c_main.c b/drivers/net/atl1c/atl1c_main.c
index 1d601ce..dec88fa 100644
--- a/drivers/net/atl1c/atl1c_main.c
+++ b/drivers/net/atl1c/atl1c_main.c
@@ -321,7 +321,10 @@ static void atl1c_del_timer(struct atl1c_adapter *adapter)
 
 static void atl1c_cancel_work(struct atl1c_adapter *adapter)
 {
-   cancel_work_sync(&adapter->reset_task);
+   if (adapter->hw.ctrl_flags & ATL1C_RESET_IN_WORK)
+       adapter->hw.ctrl_flags &= ~ATL1C_RESET_IN_WORK;/* clear the flag */
+   else
+       cancel_work_sync(&adapter->reset_task);
    cancel_work_sync(&adapter->link_chg_task);
 }
 
@@ -1544,6 +1547,7 @@ static irqreturn_t atl1c_intr(int irq, void *data)
            /* reset MAC */
            hw->intr_mask &= ~ISR_ERROR;
            AT_WRITE_REG(hw, REG_IMR, hw->intr_mask);
+           adapter->hw.ctrl_flags |= ATL1C_RESET_IN_WORK;
            schedule_work(&adapter->reset_task);
            break;
        }

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