[patch] drivers/char/esp.c: fix bootup lockup (was: Re: Linux2.6.25-rc4)

[Ingo Molnar]

randconfig testing found a bootup lockup in drivers/char/esp.c - find 
the fix below. Not sure why it became more prominent in 2.6.25-rc4, the 
bug seems rather old and i've been doing allyesconfig bootups for ages 
with CONFIG_ESP enabled.

------------->
Subject: drivers/char/esp.c: fix bootup lockup
From: Ingo Molnar <mingo@xxxxxxx>
Date: Fri Mar 07 10:47:43 CET 2008

fix this bootup lockup:

 PM: Adding info for No Bus:ttyP63
 ttyP32 at 0x0240 (irq = 0) is an ESP primary port
 BUG: spinlock lockup on CPU#0, swapper/1, f56dd004
 Pid: 1, comm: swapper Not tainted 2.6.25-rc4-sched-devel.git-x86-latest.git #402 [<c03ac6f4>] _raw_spin_lock+0x134/0x140
  [<c08649be>] _spin_lock_irqsave+0x5e/0x80
  [<c0b9fbfe>] ? espserial_init+0x2be/0x6e0
  [<c0b9fbfe>] espserial_init+0x2be/0x6e0
  [<c0b877a3>] kernel_init+0x83/0x260
  [<c0b9f940>] ? espserial_init+0x0/0x6e0
  [<c010416a>] ? restore_nocheck_notrace+0x0/0xe
  [<c0b87720>] ? kernel_init+0x0/0x260
  [<c0b87720>] ? kernel_init+0x0/0x260
  [<c0104507>] kernel_thread_helper+0x7/0x10
  =======================

kzalloc() is not the way to initialize spinlocks anymore.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 drivers/char/esp.c |    1 +
 1 file changed, 1 insertion(+)

Index: linux/drivers/char/esp.c
===================================================================
--- linux.orig/drivers/char/esp.c
+++ linux/drivers/char/esp.c
@@ -2484,6 +2484,7 @@ static int __init espserial_init(void)
 			return 0;
 		}
 
+		spin_lock_init(&info->lock);
 		/* rx_trigger, tx_trigger are needed by autoconfig */
 		info->config.rx_trigger = rx_trigger;
 		info->config.tx_trigger = tx_trigger;
--
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