Re: [PATCH] of/unittest: fix infinite loop in of_unittest_destroy_tracked_overlays()

[Petr Mladek <pmladek@suse.com>]

On Wed 2016-03-02 20:24:49, Sergey Senozhatsky wrote:
> of_overlay_destroy() can return `-ENODEV' error code once it
> failed to find the requested overlay in `ov_idr'. However,
> of_unittest_destroy_tracked_overlays() does not handle this
> error code correctly and continues to call of_overlay_destroy()
> on the 'missing' overlay over and over again. This results in
> a printk flood
> 
> [..]
> [   33.497583] of_overlay_destroy: Could not find overlay #6
> [   33.497583] of_overlay_destroy: Could not find overlay #6
> [   33.497584] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
> [   33.497584] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
> [   33.497586] of_overlay_destroy: Could not find overlay #6
> [   33.497586] of_overlay_destroy: Could not find overlay #6
> [   33.497587] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
> [   33.497587] ### dt-test ### of_unittest_destroy_tracked_overlays: overlay destroy failed for #6
> [..]
> 
> which is not really good due to printk design, and can lead to soft
> lockups, hard lockups, etc. (depending on the context console_unlock()
> is being called from). The problem has bee observed in real life
> and reported by Ying Huang.
> 
> This patch does not address the root cause of missing overlay in
> `ov_idr', it fixes the endless loop only.
> 
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> Reported-by: kernel test robot <ying.huang@linux.intel.com>
> Link: lkml.kernel.org/r/87fuwk1c0o.fsf@yhuang-dev.intel.com

I am not sure why the overlay did not exist but this patch avoids
a possible infinite loop and makes sense on its own.

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr