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

[Bruce Ashfield]

On 12-11-21 10:46 AM, Bruce Ashfield wrote:
> 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 ?

Cancel this. I *knew* the patch looked familiar .. I already have
this fix .. from Darren :)

Cheers,

Bruce

>
> 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)