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Date: Wed, 24 Dec 2014 14:29:01 +0100
From: Richard Weinberger <richard@nod.at>
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To: hujianyang <hujianyang@huawei.com>, Artem Bityutskiy <dedekind1@gmail.com>
Subject: Re: ubi_check_volume() hung on a single core system
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Am 24.12.2014 um 13:11 schrieb hujianyang:
> Hi,
> 
> When I was running mtd-utils/tests/ubi-tests/io_basic.c on a
> single core system, watchdog reset the OS and printed:
> 
> ERR:The task of feeding senior watchdog overtimes, system will reset!
> 
> io_basic.c tests the UBI_IOCVOLUP feature of UBI driver. UBI
> will perform ubi_check_volume() after updating operation is
> finished. The used ebs will be scanned for a static volume in
> this function.
> 
> If I run schedule() in the loop of eraseblock scanning, the
> *reset* not happen and the system works in right condition.
> 
> diff --git a/drivers/mtd/ubi/misc.c b/drivers/mtd/ubi/misc.c
> index dbda77e..f4f478c 100644
> --- a/drivers/mtd/ubi/misc.c
> +++ b/drivers/mtd/ubi/misc.c
> @@ -74,6 +74,9 @@ int ubi_check_volume(struct ubi_device *ubi, int vol_id)
>         for (i = 0; i < vol->used_ebs; i++) {
>                 int size;
> 
> +               set_current_state(TASK_UNINTERRUPTIBLE);
> +               schedule_timeout(HZ/10);

cond_resched() please.

>                 if (i == vol->used_ebs - 1)
>                         size = vol->last_eb_bytes;
>                 else
> 
> 
> 
> I think this error can't be re-created on a multi-core system.
> It can only happen on a single core system. This directly
> schedule I modified would hurt the performance of volume check.
> 
> Does anyone interested in this issue?

Of course!

Thanks,
//richard