On Mon, 18 Aug 2008 18:54:57 +0300
"ext Artem Bityutskiy" <Artem.Bityutskiy@xxxxxxxxx> wrote:
> This patch fixes the following annoying warning:
>
> INFO: task twl4030 gpio:283 blocked for more than 120 seconds.
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
> message. twl4030 gpio D c027e9dc 0 283 2
> [<c027e744>] (schedule+0x0/0x314) from [<c00640f0>] (kthread
> +0x3c/0x80) [<c00640b4>] (kthread+0x0/0x80) from [<c0052678>] (do_exit
> +0x0/0x664) r5:00000000 r4:00000000
>
> Which is printed every 120 seconds by the softlockup code (see
> 'check_hung_task()' function, introduced by on Jan 2008 by commit
> 82a1fcb90287052aabfa235e7ffc693ea003fe69).
>
> The reason is that the "twl4030 gpio" kthread is created but is not
> started immediatelly. And in fact it may never start, because TWL3040
> interrupts may never happen and hence, the
> 'twl4030_gpio_unmask_irqchip()' function is never run. This makes the
> softlockup detection code unhappy.
>
> Fix this by running the "twl4030 gpio" kernel thread in at the end of
> the 'gpio_twl4030_init()' initialization function. Since the
> 'gpio_pending_unmask' global variable is 0 at that time, the tread
> ('twl4030_gpio_unmask_thread()') will effectively do nothing and go
> sleep. This makes the softlocup detection code happy.
>
This is good. It fixes also second issue where system load average is
always above 1 since task is in uninterruptible state before this first
wake-up.
Jarkko
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