net: fec: fix spin_lock dead lock
=========================================================
[ INFO: possible irq lock inversion dependency detected ]
3.8.0-rc5+ #82 Not tainted
---------------------------------------------------------
swapper/0/0 just changed the state of lock:
(&(&fep->hw_lock)->rlock){..-...}, at: [<8034e2f8>] fec_enet_start_xmit+0x48/0x 2cc
but this lock took another, SOFTIRQ-unsafe lock in the past:
(prepare_lock){+.+.+.}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(prepare_lock);
local_irq_disable()
lock(&(&fep->hw_lock)->rlock);
lock(prepare_lock);
<Interrupt>
lock(&(&fep->hw_lock)->rlock);
*** DEADLOCK ***
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
index c40526c..1f17ca0 100644
--- a/drivers/net/ethernet/freescale/fec_ptp.c
+++ b/drivers/net/ethernet/freescale/fec_ptp.c
@@ -104,7 +104,7 @@
unsigned long flags;
int inc;
- inc = 1000000000 / clk_get_rate(fep->clk_ptp);
+ inc = 1000000000 / fep->cycle_speed;
/* grab the ptp lock */
spin_lock_irqsave(&fep->tmreg_lock, flags);
@@ -363,6 +363,8 @@
fep->ptp_caps.settime = fec_ptp_settime;
fep->ptp_caps.enable = fec_ptp_enable;
+ fep->cycle_speed = clk_get_rate(fep->clk_ptp);
+
spin_lock_init(&fep->tmreg_lock);
fec_ptp_start_cyclecounter(ndev);