net: add a new @alloc parameter to napi_skb_cache_get()

We want to be able in the series last patch to get an skb from
napi_skb_cache from process context, if there is one available.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251116202717.1542829-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f34372666e67cee5329d3ba1d3c86f8622facac3..88b5530f9c460d86e12c98e410774444367e0404 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -280,17 +280,18 @@ EXPORT_SYMBOL(__netdev_alloc_frag_align);
  */
 static u32 skbuff_cache_size __read_mostly;
 
-static struct sk_buff *napi_skb_cache_get(void)
+static struct sk_buff *napi_skb_cache_get(bool alloc)
 {
        struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
        struct sk_buff *skb;
 
        local_lock_nested_bh(&napi_alloc_cache.bh_lock);
        if (unlikely(!nc->skb_count)) {
-               nc->skb_count = kmem_cache_alloc_bulk(net_hotdata.skbuff_cache,
-                                                     GFP_ATOMIC | __GFP_NOWARN,
-                                                     NAPI_SKB_CACHE_BULK,
-                                                     nc->skb_cache);
+               if (alloc)
+                       nc->skb_count = kmem_cache_alloc_bulk(net_hotdata.skbuff_cache,
+                                               GFP_ATOMIC | __GFP_NOWARN,
+                                               NAPI_SKB_CACHE_BULK,
+                                               nc->skb_cache);
                if (unlikely(!nc->skb_count)) {
                        local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
                        return NULL;
@@ -530,7 +531,7 @@ static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
 {
        struct sk_buff *skb;
 
-       skb = napi_skb_cache_get();
+       skb = napi_skb_cache_get(true);
        if (unlikely(!skb))
                return NULL;
 
@@ -659,7 +660,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
        /* Get the HEAD */
        if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
            likely(node == NUMA_NO_NODE || node == numa_mem_id()))
-               skb = napi_skb_cache_get();
+               skb = napi_skb_cache_get(true);
        else
                skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
        if (unlikely(!skb))