linux-kernel - Re: [PATCH v4 2/2] staging: android: Remove BUG from ion_system

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Message-ID: <20200824114332.GN5493@kadam>
Date:   Mon, 24 Aug 2020 14:43:32 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Tomer Samara <tomersamara98@...il.com>,
        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 v4 2/2] staging: android: Remove BUG from
 ion_system_heap.c

On Mon, Aug 24, 2020 at 02:27:08PM +0300, Dan Carpenter wrote:
> On Mon, Aug 24, 2020 at 02:24:57PM +0300, Dan Carpenter wrote:
> > On Fri, Aug 21, 2020 at 09:25:26AM -0700, Randy Dunlap wrote:
> > > On 8/21/20 8:28 AM, Tomer Samara wrote:
> > > > Remove BUG() from ion_sytem_heap.c
> > > > 
> > > > 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 | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
> > > > index eac0632ab4e8..00d6154aec34 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();
> > > > +	/* This is impossible. */
> > > >  	return -1;
> > > >  }
> > > 
> > > Hi,
> > > Please explain why this is impossible.
> > > 
> > > If some caller calls order_to_index(5), it will return -1, yes?
> > > 
> > 
> > I was happy enough with the comment as-is given that I suggested it.
> > But an alternative comment could be "/* This is impossible.
> > We always pass valid values to this function. */
> 
> Another option is to just change the BUG_ON() to a WARN_ON().  I feel
> like that communicates the same thing but makes checkpatch happy.

Actually earlier Greg pointed out that some systems have panic on warn
so WARN_ON() doesn't work.  Just add the comment.

regards,
dan carpenter