Re: [PATCH 5/6] fscrypt: cache the HMAC transform for each master key

[Eric Biggers <ebiggers3@gmail.com>]

On Mon, Jul 17, 2017 at 10:45:51AM -0700, Michael Halcrow wrote:
> > +/*
> > + * Get the fscrypt_master_key identified by the specified v2+ encryption
> > + * context, or create it if not found.
> > + *
> > + * Returns the fscrypt_master_key with a reference taken, or an ERR_PTR().
> > + */
> > +static struct fscrypt_master_key *
> > +find_or_create_master_key(const struct inode *inode,
> > +			  const struct fscrypt_context *ctx,
> > +			  unsigned int min_keysize)
> > +{
> > +	struct fscrypt_master_key *master_key;
> > +
> > +	if (WARN_ON(ctx->version < FSCRYPT_CONTEXT_V2))
> > +		return ERR_PTR(-EINVAL);
> 
> Isn't this a programming error?  If so, consider either BUG_ON() or
> omit the check.
> 

Yes, but BUG_ON() is discouraged in cases where there is a straightforward way
to recover from the error.  checkpatch actually warns about using it these days.

Eric