[linux-yocto] Fwd: [PATCH] serial: pch_uart: no need to disable irq for -rt kernel

[Bruce Ashfield]

Looping this via the linux-yocto mailing list as well, since I plan to
merge this to the 3.4 yocto kernel (with a slightly tweaked header),
which shares the same base and will have the same problem.

Darren: does this look fine to you ?

Cheers,

Bruce


-------- Original Message --------
Subject: [PATCH] serial: pch_uart: no need to disable irq for -rt kernel
Date: Wed, 21 Nov 2012 16:23:30 +0800
From: Liang Li <liang.li at windriver.com>

Fix the following call trace when ttyPCH* is used as serial console:

BUG: sleeping function called from invalid context at
../linux/kernel/rtmutex.c:646

in_atomic(): 0, irqs_disabled(): 1, pid: 12, name: kworker/0:1
Pid: 12, comm: kworker/0:1 Tainted: G W
3.4.16-rt17-preempt-rt #1
Call Trace:
[<c1057236>] __might_sleep+0xd6/0x100
[<c163892c>] rt_spin_lock+0x1c/0x40
[<c1351c18>] pch_console_write+0x58/0x1c0
[<c102a4cb>] __call_console_drivers+0x7b/0xa0
[<c102a653>] _call_console_drivers+0x73/0x120
[<c163c51d>] ? sub_preempt_count+0x7d/0xb0
[<c102a9c1>] console_unlock+0xf1/0x250
[<c1346179>] console_callback+0x79/0x120
[<c1045177>] process_one_work+0x107/0x410
[<c1346100>] ? poke_blanked_console+0xc0/0xc0
[<c1346100>] ? poke_blanked_console+0xc0/0xc0
[<c10459c5>] worker_thread+0x135/0x2e0
[<c1045890>] ? manage_workers.isra.26+0x200/0x200
[<c1045890>] ? manage_workers.isra.26+0x200/0x200
[<c104a5e3>] kthread+0x73/0x80
[<c104a570>] ? __init_kthread_worker+0x40/0x40
[<c163f9fa>] kernel_thread_helper+0x6/0x10
BUG: sleeping function called from invalid context at ...

Signed-off-by: Liang Li <liang.li at windriver.com>
---
  drivers/tty/serial/pch_uart.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 7d47514..604fcc0 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -1551,7 +1551,7 @@ pch_console_write(struct console *co, const char 
*s, unsigned int count)

  	touch_nmi_watchdog();

-	local_irq_save(flags);
+	local_irq_save_nort(flags);
  	if (priv->port.sysrq) {
  		spin_lock(&priv->lock);
  		/* serial8250_handle_port() already took the port lock */
@@ -1584,7 +1584,7 @@ pch_console_write(struct console *co, const char 
*s, unsigned int count)
  		spin_unlock(&priv->port.lock);
  	if (priv_locked)
  		spin_unlock(&priv->lock);
-	local_irq_restore(flags);
+	local_irq_restore_nort(flags);
  }

  static int __init pch_console_setup(struct console *co, char *options)
-- 
1.7.11.4