xsk: Bump xsk_queue::queue_empty_descs in xp_can_alloc()

We have STAT_FILL_EMPTY test case in xskxceiver that tries to process
traffic with fill queue being empty which currently fails for zero copy
ice driver after it started to use xsk_buff_can_alloc() API. That is
because xsk_queue::queue_empty_descs is currently only increased from
alloc APIs and right now if driver sees that xsk_buff_pool will be
unable to provide the requested count of buffers, it bails out early,
skipping calls to xsk_buff_alloc{_batch}().

Mentioned statistic should be handled in xsk_buff_can_alloc() from the
very beginning, so let's add this logic now. Do it by open coding
xskq_cons_has_entries() and bumping queue_empty_descs in the middle when
fill queue currently has no entries.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240904162808.249160-1-maciej.fijalkowski@intel.com

diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index c0e0204b9630450534f0c32527d40ff02d8175cf..dad7849c1b7547c886d7aedb0330731f02f74f47 100644 (file)
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -656,9 +656,17 @@ EXPORT_SYMBOL(xp_alloc_batch);
 
 bool xp_can_alloc(struct xsk_buff_pool *pool, u32 count)
 {
+       u32 req_count, avail_count;
+
        if (pool->free_list_cnt >= count)
                return true;
-       return xskq_cons_has_entries(pool->fq, count - pool->free_list_cnt);
+
+       req_count = count - pool->free_list_cnt;
+       avail_count = xskq_cons_nb_entries(pool->fq, req_count);
+       if (!avail_count)
+               pool->fq->queue_empty_descs++;
+
+       return avail_count >= req_count;
 }
 EXPORT_SYMBOL(xp_can_alloc);
 

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 6f2d1621c9922181c3ea8bd44dfc4c49a110fb02..406b20dfee8d4783a28bba3e03b7c7553301b087 100644 (file)
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -306,11 +306,6 @@ static inline u32 xskq_cons_nb_entries(struct xsk_queue *q, u32 max)
        return entries >= max ? max : entries;
 }
 
-static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
-{
-       return xskq_cons_nb_entries(q, cnt) >= cnt;
-}
-
 static inline bool xskq_cons_peek_addr_unchecked(struct xsk_queue *q, u64 *addr)
 {
        if (q->cached_prod == q->cached_cons)