On Wed, Nov 07, 2018 at 12:39:24PM +0000, Ophir Munk wrote: > > -----Original Message----- > > From: Adrien Mazarguil [mailto:adrien.mazarg...@6wind.com] > > Sent: Wednesday, November 07, 2018 11:31 AM > > To: Ophir Munk <ophi...@mellanox.com> > > Cc: Ferruh Yigit <ferruh.yi...@intel.com>; Andrew Rybchenko > > <arybche...@solarflare.com>; dev@dpdk.org; Thomas Monjalon > > <tho...@monjalon.net>; Asaf Penso <as...@mellanox.com>; Shahaf > > Shuler <shah...@mellanox.com>; Olga Shern <ol...@mellanox.com> > > Subject: Re: [dpdk-dev] [PATCH v2] ethdev: document RSS default key and > > types > > > > On Wed, Nov 07, 2018 at 09:23:42AM +0000, Ophir Munk wrote: > > > struct rte_flow_action_rss include fields 'key' and 'types'. > > > Field 'key' is a pointer to bytes array (uint8_t *) which contains the > > > specific RSS hash key. > > > If an application is only interested in default RSS operation it > > > should not care about the specific hash key. The application can set > > > the hash key to NULL such that any PMD uses its default RSS key. > > > > > > Field 'types' is a uint64_t bits flag used to specify a specific RSS > > > hash type such as ETH_RSS_IP (see ETH_RSS_*). > > > If an application does not care about the specific RSS type it can set > > > this field to 0 such that any PMD uses its default type. > > > > > > Signed-off-by: Ophir Munk <ophi...@mellanox.com> > > > --- > > > lib/librte_ethdev/rte_flow.h | 9 +++++++-- > > > 1 file changed, 7 insertions(+), 2 deletions(-) > > > > > > diff --git a/lib/librte_ethdev/rte_flow.h > > > b/lib/librte_ethdev/rte_flow.h index c0fe879..ca9e135 100644 > > > --- a/lib/librte_ethdev/rte_flow.h > > > +++ b/lib/librte_ethdev/rte_flow.h > > > @@ -1782,10 +1782,15 @@ struct rte_flow_action_rss { > > > * through. > > > */ > > > uint32_t level; > > > - uint64_t types; /**< Specific RSS hash types (see ETH_RSS_*). */ > > > + /** > > > + * Specific RSS hash types (see ETH_RSS_*), > > > + * or 0 for PMD specific default. > > > + */ > > > + uint64_t types; > > > uint32_t key_len; /**< Hash key length in bytes. */ > > > uint32_t queue_num; /**< Number of entries in @p queue. */ > > > - const uint8_t *key; /**< Hash key. */ > > > + /** Hash key, or NULL for PMD specific default key. */ > > > + const uint8_t *key; > > > > I'd suggest to document that on key_len instead. If key_len is nonzero, key > > cannot be NULL anyway. > > The decision if a key/len combination is valid is done in the PMD action > validation API. > For example, in MLX5 key==NULL and key_len==40 is accepted. > The combination key==NULL and key_len==0 should always succeeds, however the > "must" parameter for RSS default is key==NULL and not key_len==0.
I understand this is how the mlx5 PMD implemented it, but my point is that it makes more sense API-wise to define key_len == 0 as the trigger for a default RSS hash key than key == NULL. My suggestion is to follow the same trend as memcpy(), mmap(), snprintf() and other well-known functions that take a size when dealing with NULL/undefined pointers. Only size matters! :) -- Adrien Mazarguil 6WIND
