[PATCH net-next] tcp: remove unused hash_size from struct tcp_out_options

hash_size is declared but never read. The MD5 path always uses a
fixed size of 16, and the TCP-AO path uses tcp_ao_maclen().

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Keita Morisaki <redacted>
---
 net/ipv4/tcp_output.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 63ee037f46e50..f0e04ebd8b723 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c

@@ -441,7 +441,6 @@ struct tcp_out_options {
 	u8 ws;			/* window scale, 0 to disable */
 	u8 num_accecn_fields:7,	/* number of AccECN fields needed */
 	   use_synack_ecn_bytes:1; /* Use synack_ecn_bytes or not */
-	u8 hash_size;		/* bytes in hash_location */
 	__u8 *hash_location;	/* temporary pointer, overloaded */
 	__u32 tsval, tsecr;	/* need to include OPTION_TS */
 	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */

base-commit: 21fc6b53f12379f3f9b29830be3597a322261df8
-- 
2.34.1

On Wed, Mar 4, 2026 at 6:27 PM Keita Morisaki [off-list ref] wrote:

hash_size is declared but never read. The MD5 path always uses a
fixed size of 16, and the TCP-AO path uses tcp_ao_maclen().

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Keita Morisaki <redacted>

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

On Wed, Mar 4, 2026 at 8:37 PM Kuniyuki Iwashima [off-list ref] wrote:

On Wed, Mar 4, 2026 at 6:27 PM Keita Morisaki [off-list ref] wrote:

quoted

hash_size is declared but never read. The MD5 path always uses a
fixed size of 16, and the TCP-AO path uses tcp_ao_maclen().

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Keita Morisaki <redacted>

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

btw, AFAIU, patchwork does not use git am -3, and this does
not cleanly apply after your another patch and you'll need to respin.

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

Thank you so much for the quick review!

btw, AFAIU, patchwork does not use git am -3, and this does
not cleanly apply after your another patch and you'll need to respin.

You're right. Since the first patch (https://lore.kernel.org/netdev/20260304111517.2088694-1-kmta1236@gmail.com/) seems to be close to being merged,
maybe I should rebase this patch on top of the first one after the first one is merged?

On Wed, Mar 4, 2026 at 8:53 PM Keita Morisaki [off-list ref] wrote:

quoted

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

Thank you so much for the quick review!

quoted

btw, AFAIU, patchwork does not use git am -3, and this does
not cleanly apply after your another patch and you'll need to respin.

You're right. Since the first patch (https://lore.kernel.org/netdev/20260304111517.2088694-1-kmta1236@gmail.com/) seems to be close to being merged,
maybe I should rebase this patch on top of the first one after the first one is merged?

Yes, please rebase and send v2 after the patch is merged
(and 24h passes from v1).