[PATCH RFC net-next 10/34] xdp: constify read-only arguments of some static inline helpers

[Alexander Lobakin <aleksander.lobakin@intel.com>]

Lots of read-only helpers for &xdp_buff and &xdp_frame, such as getting
the frame length, skb_shared_info etc., don't have their arguments
marked with `const` for no reason. Add the missing annotations to leave
less place for mistakes and more for optimization.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
 include/net/xdp.h | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index e6770dd40c91..197808df1ee1 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -88,7 +88,7 @@ struct xdp_buff {
 	u32 flags; /* supported values defined in xdp_buff_flags */
 };
 
-static __always_inline bool xdp_buff_has_frags(struct xdp_buff *xdp)
+static __always_inline bool xdp_buff_has_frags(const struct xdp_buff *xdp)
 {
 	return !!(xdp->flags & XDP_FLAGS_HAS_FRAGS);
 }
@@ -103,7 +103,8 @@ static __always_inline void xdp_buff_clear_frags_flag(struct xdp_buff *xdp)
 	xdp->flags &= ~XDP_FLAGS_HAS_FRAGS;
 }
 
-static __always_inline bool xdp_buff_is_frag_pfmemalloc(struct xdp_buff *xdp)
+static __always_inline bool
+xdp_buff_is_frag_pfmemalloc(const struct xdp_buff *xdp)
 {
 	return !!(xdp->flags & XDP_FLAGS_FRAGS_PF_MEMALLOC);
 }
@@ -144,15 +145,16 @@ xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,
 	 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 
 static inline struct skb_shared_info *
-xdp_get_shared_info_from_buff(struct xdp_buff *xdp)
+xdp_get_shared_info_from_buff(const struct xdp_buff *xdp)
 {
 	return (struct skb_shared_info *)xdp_data_hard_end(xdp);
 }
 
-static __always_inline unsigned int xdp_get_buff_len(struct xdp_buff *xdp)
+static __always_inline unsigned int
+xdp_get_buff_len(const struct xdp_buff *xdp)
 {
 	unsigned int len = xdp->data_end - xdp->data;
-	struct skb_shared_info *sinfo;
+	const struct skb_shared_info *sinfo;
 
 	if (likely(!xdp_buff_has_frags(xdp)))
 		goto out;
@@ -177,12 +179,13 @@ struct xdp_frame {
 	u32 flags; /* supported values defined in xdp_buff_flags */
 };
 
-static __always_inline bool xdp_frame_has_frags(struct xdp_frame *frame)
+static __always_inline bool xdp_frame_has_frags(const struct xdp_frame *frame)
 {
 	return !!(frame->flags & XDP_FLAGS_HAS_FRAGS);
 }
 
-static __always_inline bool xdp_frame_is_frag_pfmemalloc(struct xdp_frame *frame)
+static __always_inline bool
+xdp_frame_is_frag_pfmemalloc(const struct xdp_frame *frame)
 {
 	return !!(frame->flags & XDP_FLAGS_FRAGS_PF_MEMALLOC);
 }
@@ -201,7 +204,7 @@ static __always_inline void xdp_frame_bulk_init(struct xdp_frame_bulk *bq)
 }
 
 static inline struct skb_shared_info *
-xdp_get_shared_info_from_frame(struct xdp_frame *frame)
+xdp_get_shared_info_from_frame(const struct xdp_frame *frame)
 {
 	void *data_hard_start = frame->data - frame->headroom - sizeof(*frame);
 
@@ -249,7 +252,8 @@ int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp);
 struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf);
 
 static inline
-void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
+void xdp_convert_frame_to_buff(const struct xdp_frame *frame,
+			       struct xdp_buff *xdp)
 {
 	xdp->data_hard_start = frame->data - frame->headroom - sizeof(*frame);
 	xdp->data = frame->data;
@@ -260,7 +264,7 @@ void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
 }
 
 static inline
-int xdp_update_frame_from_buff(struct xdp_buff *xdp,
+int xdp_update_frame_from_buff(const struct xdp_buff *xdp,
 			       struct xdp_frame *xdp_frame)
 {
 	int metasize, headroom;
@@ -317,9 +321,10 @@ void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
 			   struct xdp_frame_bulk *bq);
 
-static __always_inline unsigned int xdp_get_frame_len(struct xdp_frame *xdpf)
+static __always_inline unsigned int
+xdp_get_frame_len(const struct xdp_frame *xdpf)
 {
-	struct skb_shared_info *sinfo;
+	const struct skb_shared_info *sinfo;
 	unsigned int len = xdpf->len;
 
 	if (likely(!xdp_frame_has_frags(xdpf)))
-- 
2.43.0