Re: [PATCH 1/5] lib/rhashtable: convert param sanitations to WARN_ON

From: Davidlohr Bueso
Date: Fri Jun 01 2018 - 12:54:07 EST


On Sat, 02 Jun 2018, Herbert Xu wrote:

On Fri, Jun 01, 2018 at 09:01:21AM -0700, Davidlohr Bueso wrote:
For the purpose of making rhashtable_init() unable to fail,
we can replace the returning -EINVAL with WARN_ONs whenever
the caller passes bogus parameters during initialization.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
---
lib/rhashtable.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 9427b5766134..05a4b1b8b8ce 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -1024,12 +1024,11 @@ int rhashtable_init(struct rhashtable *ht,

size = HASH_DEFAULT_SIZE;

- if ((!params->key_len && !params->obj_hashfn) ||
- (params->obj_hashfn && !params->obj_cmpfn))
- return -EINVAL;
+ WARN_ON((!params->key_len && !params->obj_hashfn) ||
+ (params->obj_hashfn && !params->obj_cmpfn));

- if (params->nulls_base && params->nulls_base < (1U << RHT_BASE_SHIFT))
- return -EINVAL;
+ WARN_ON(params->nulls_base &&
+ params->nulls_base < (1U << RHT_BASE_SHIFT));

I still don't like this.

Yes for your use-case you will never crash and a WARN_ON is fine.
However, rhashtable is used in all sorts of contexts and returning
an error makes sense for quite a number of them.

Curious, are these users setting up the param structure dynamically
or something that they can pass along bogus values?

If that's the case then yes, I definitely agree.