Re: [PATCH 1/1] net: fec: fix miss init spinlock

2013/2/5 Dmitry Eremin-Solenikov [off-list ref]:

On Fri, 01 Feb 2013 16:56:26 +0800, Frank Li wrote:

quoted

BUG: spinlock bad magic on CPU#1, swapper/0/1 lock: 0xbfae0f8c, .magic:
00000000, .owner: <none>/-1, .owner_cpu: 0 Backtrace:
 [<80011d54>] (dump_backtrace+0x0/0x10c) from [<804e7800>]
 (dump_stack+0x18/0x1c)
 r6:bfae0000 r5:bfae0f8c r4:00000000 r3:806c1310 [<804e77e8>]
 (dump_stack+0x0/0x1c) from [<804e9f20>] (spin_dump+0x80/0x94)
 [<804e9ea0>] (spin_dump+0x0/0x94) from [<804e9f60>]
 (spin_bug+0x2c/0x30)
 r5:805f6f8c r4:bfae0f8c [<804e9f34>] (spin_bug+0x0/0x30) from
 [<80257984>] (do_raw_spin_lock+0x170/0x1b0
            )
 r5:806b4950 r4:bfae0f8c [<80257814>] (do_raw_spin_lock+0x0/0x1b0) from
 [<804ed15c>] (_raw_spin_lock_irqs
   ave+0x18/0x20) [<804ed144>] (_raw_spin_lock_irqsave+0x0/0x20) from
 [<8033c694>] (fec_ptp_start_
 cyclecounter+0x3c/0x120)
 r4:bfae0f8c r3:00000002 [<8033c658>]
 (fec_ptp_start_cyclecounter+0x0/0x120) from [<80339e08>] (fec_resta
                                     rt+0x56c/0x5f8) r8:00000000
 r7:806e6f48 r6:00000112 r5:806b4950 r4:bfae0000 [<8033989c>]
 (fec_restart+0x0/0x5f8) from [<8033b9e4>] (fec_probe+0x508/0xa48)

Signed-off-by: Frank Li <redacted>
---
 drivers/net/ethernet/freescale/fec.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.c

b/drivers/net/ethernet/freescale/fec.c index 69b16b9..f900ae4 100644 ---
a/drivers/net/ethernet/freescale/fec.c +++
b/drivers/net/ethernet/freescale/fec.c @@ -1607,6 +1607,7 @@ static int
fec_enet_init(struct net_device *ndev)
      }

      spin_lock_init(&fep->hw_lock);
+     spin_lock_init(&fep->tmreg_lock);

      fep->netdev = ndev;

Please excuse me, if I'm wrong. I would consider this as a very wrong
solution:

First, then the spin lock is initialised twice (first time in
fec_enet_init(), second time in fec_ptp_init()).

Then this patch actually hides the fact that PTP part of fec
is accessed from fec_ptp_start_cyclecounter() way before
than fec_ptp_init() is called to initialize PTP).

In my opinion the right patch should either move fec_ptp_init() call
before fec_restart(), or make fec_restart intelelctual about calling
fec_ptp_init()/fec_ptp_startcyclecounter() at proper time.

Yes, you are right.

--
With best wishes
Dmitry


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