linux-kernel - Re: [PATCH v3 2/2] staging: android: Remove BUG from ion_system

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Message-ID: <20200821133210.GV1793@kadam>
Date:   Fri, 21 Aug 2020 16:32:10 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Tomer Samara <tomersamara98@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        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 v3 2/2] staging: android: Remove BUG from
 ion_system_heap.c

On Wed, Aug 19, 2020 at 10:39:34PM +0300, Tomer Samara wrote:
> Remove BUG()  at ion_sytem_heap.c and error handling to:
>  - free_buffer_page
>  - alloc_buffer_page
> this fix the following checkpatch issue:
> Avoid crashing the kernel - try using WARN_ON &
> recovery code ratherthan BUG() or BUG_ON().
> 
> Signed-off-by: Tomer Samara <tomersamara98@...il.com>
> ---
>  drivers/staging/android/ion/ion_system_heap.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
> index eac0632ab4e8..56d53268b82c 100644
> --- a/drivers/staging/android/ion/ion_system_heap.c
> +++ b/drivers/staging/android/ion/ion_system_heap.c
> @@ -30,7 +30,7 @@ static int order_to_index(unsigned int order)
>  	for (i = 0; i < NUM_ORDERS; i++)
>  		if (order == orders[i])
>  			return i;
> -	BUG();
> +
>  	return -1;
>  }

Just delete the BUG() and put a comment that /* This is impossible. */
so that reviewers know that we never return -1.

I suspect that there are some static analysis tools which might complain
about this -1 return.  But those tools are pretty crap.  Never change
code just to make the tools happy.

regards,
dan carpenter