[PATCH hotfix 6.11 v2 2/3] minmax: reduce min/max macro expansion in skbuff

From: Lorenzo Stoakes
Date: Wed Sep 11 2024 - 13:52:18 EST


Avoid unnecessary nested min()/max() which reults in egregious macro
expansion.

The nesting occurs when NET_SKB_PAD is used in a min() or max() invocation,
for instance, various ethernet drivers wrap it in a max().

Not doing so results in an impact on build times.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 867046cc7027 ("minmax: relax check to allow comparison between unsigned arguments and signed constants")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
---
include/linux/skbuff.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 29c3ea5b6e93..d53b296df504 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3164,7 +3164,11 @@ static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
* NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
*/
#ifndef NET_SKB_PAD
-#define NET_SKB_PAD max(32, L1_CACHE_BYTES)
+#if L1_CACHE_BYTES < 32
+#define NET_SKB_PAD 32
+#else
+#define NET_SKB_PAD L1_CACHE_BYTES
+#endif
#endif

int ___pskb_trim(struct sk_buff *skb, unsigned int len);
--
2.46.0