linux-kernel - [PATCH bpf-next] xsk: Simplify xp_aligned_validate

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Message-Id: <20230410121841.643254-1-kal.conley@dectris.com>
Date:   Mon, 10 Apr 2023 14:18:41 +0200
From:   Kal Conley <kal.conley@...tris.com>
To:     Björn Töpel <bjorn@...nel.org>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>
Cc:     Kal Conley <kal.conley@...tris.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next] xsk: Simplify xp_aligned_validate_desc implementation

Perform the chunk boundary check like the page boundary check in
xp_desc_crosses_non_contig_pg(). This simplifies the implementation and
reduces the number of branches.

Signed-off-by: Kal Conley <kal.conley@...tris.com>
---
 net/xdp/xsk_queue.h | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index dea4f378327d..6d40a77fccbe 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -133,16 +133,12 @@ static inline bool xskq_cons_read_addr_unchecked(struct xsk_queue *q, u64 *addr)
 static inline bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
 					    struct xdp_desc *desc)
 {
-	u64 chunk, chunk_end;
+	u64 offset = desc->addr & (pool->chunk_size - 1);
 
-	chunk = xp_aligned_extract_addr(pool, desc->addr);
-	if (likely(desc->len)) {
-		chunk_end = xp_aligned_extract_addr(pool, desc->addr + desc->len - 1);
-		if (chunk != chunk_end)
-			return false;
-	}
+	if (offset + desc->len > pool->chunk_size)
+		return false;
 
-	if (chunk >= pool->addrs_cnt)
+	if (desc->addr >= pool->addrs_cnt)
 		return false;
 
 	if (desc->options)
-- 
2.39.2