Re: [PATCH v3 01/10] mtd: powernv_flash: Use WARN_ON_ONCE() rather than BUG_ON()

On Mon, 2017-07-17 at 13:33 +0200, Frans Klaver wrote:

On Wed, Jul 12, 2017 at 6:22 AM, Cyril Bur [off-list ref] wrote:

quoted

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 <redacted>
---
 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