linux-kernel - Re: [PATCH v2 1/4] staging: android: Replace BUG_ON with WARN

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Date:   Tue, 18 Aug 2020 16:11:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Tomer Samara <tomersamara98@...il.com>
Cc:     devel@...verdev.osuosl.org, Todd Kjos <tkjos@...roid.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Riley Andrews <riandrews@...roid.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Hridya Valsaraju <hridya@...gle.com>,
        Arve Hjønnevåg <arve@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Laura Abbott <labbott@...hat.com>,
        Martijn Coenen <maco@...roid.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian Brauner <christian@...uner.io>
Subject: Re: [PATCH v2 1/4] staging: android: Replace BUG_ON with WARN_ON

On Sun, Aug 16, 2020 at 10:23:25PM +0300, Tomer Samara wrote:
> BUG_ON() is replaced with WARN_ON at ion_page_pool.c

Why?

> Fixes the following issue:
> Avoid crashing the kernel - try using WARN_ON & recovery code ratherthan BUG() or BUG_ON().

Ideally you can get rid of WARN_ON() too, right?

Many systems run in panic-on-warn mode, so this really does not change
anything.  Try fixing this up properly to not crash at all.

> 
> Signed-off-by: Tomer Samara <tomersamara98@...il.com>
> ---
>  drivers/staging/android/ion/ion_page_pool.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
> index 0198b886d906..c1b9eda35c96 100644
> --- a/drivers/staging/android/ion/ion_page_pool.c
> +++ b/drivers/staging/android/ion/ion_page_pool.c
> @@ -46,11 +46,13 @@ static struct page *ion_page_pool_remove(struct ion_page_pool *pool, bool high)
>  	struct page *page;
>  
>  	if (high) {
> -		BUG_ON(!pool->high_count);
> +		if (WARN_ON(!pool->high_count))
> +			return NULL;

And can you test this that it works properly?

thanks,

greg k-h