From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x242.google.com (mail-pf0-x242.google.com [IPv6:2607:f8b0:400e:c00::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xBLb44hV3zDrDF for ; Tue, 18 Jul 2017 10:27:28 +1000 (AEST) Received: by mail-pf0-x242.google.com with SMTP id a11so589641pfj.3 for ; Mon, 17 Jul 2017 17:27:28 -0700 (PDT) Message-ID: <1500337639.2475.1.camel@gmail.com> Subject: Re: [PATCH v3 01/10] mtd: powernv_flash: Use WARN_ON_ONCE() rather than BUG_ON() From: Cyril Bur To: Frans Klaver Cc: linuxppc-dev@lists.ozlabs.org, linux-mtd@lists.infradead.org, stewart@linux.vnet.ibm.com, benh@kernel.crashing.org, alistair@popple.id.au, David Woodhouse , rlippert@google.com Date: Tue, 18 Jul 2017 10:27:19 +1000 In-Reply-To: References: <20170712042304.19745-1-cyrilbur@gmail.com> <20170712042304.19745-2-cyrilbur@gmail.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2017-07-17 at 13:33 +0200, Frans Klaver wrote: > On Wed, Jul 12, 2017 at 6:22 AM, Cyril Bur wrote: > > BUG_ON() should be reserved in situations where we can not longer > > guarantee the integrity of the system. In the case where > > powernv_flash_async_op() receives an impossible op, we can still > > guarantee the integrity of the system. > > > > Signed-off-by: Cyril Bur > > --- > > drivers/mtd/devices/powernv_flash.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/mtd/devices/powernv_flash.c b/drivers/mtd/devices/powernv_flash.c > > index f5396f26ddb4..a9a20c00687c 100644 > > --- a/drivers/mtd/devices/powernv_flash.c > > +++ b/drivers/mtd/devices/powernv_flash.c > > @@ -78,7 +78,8 @@ static int powernv_flash_async_op(struct mtd_info *mtd, enum flash_op op, > > rc = opal_flash_erase(info->id, offset, len, token); > > break; > > default: > > - BUG_ON(1); > > + WARN_ON_ONCE(1); > > + return -EIO; > > Based on the fact that all three values in enum flash_op are handled, > I would go as far as stating that the default lemma adds no value and > can be removed. > The way I see it is that it isn't doing any harm being there and in cases of future programmer error or during corruption events, that WARN_ON might prove useful. > Frans