diff mbox series

[net-next] tcp: fix tcp_grow_skb() vs tstamps

Message ID 20240425193450.411640-1-edumazet@google.com (mailing list archive)
State Accepted
Commit 1bede0a12d3a45bd366d3cf9e1c7611d86f1bc1f
Delegated to: Netdev Maintainers
Headers show
Series [net-next] tcp: fix tcp_grow_skb() vs tstamps | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 928 this patch: 928
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 1 maintainers not CCed: dsahern@kernel.org
netdev/build_clang success Errors and warnings before: 940 this patch: 940
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 939 this patch: 939
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 52 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 1 this patch: 1
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-04-26--09-00 (tests: 993)

Commit Message

Eric Dumazet April 25, 2024, 7:34 p.m. UTC 
I forgot to call tcp_skb_collapse_tstamp() in the
case we consume the second skb in write queue.

Neal suggested to create a common helper used by tcp_mtu_probe()
and tcp_grow_skb().

Fixes: 8ee602c63520 ("tcp: try to send bigger TSO packets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
---
 net/ipv4/tcp_output.c | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

Comments

Neal Cardwell April 25, 2024, 8:34 p.m. UTC | #1 
On Thu, Apr 25, 2024 at 3:34 PM Eric Dumazet <edumazet@google.com> wrote:
>
> I forgot to call tcp_skb_collapse_tstamp() in the
> case we consume the second skb in write queue.
>
> Neal suggested to create a common helper used by tcp_mtu_probe()
> and tcp_grow_skb().
>
> Fixes: 8ee602c63520 ("tcp: try to send bigger TSO packets")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Neal Cardwell <ncardwell@google.com>
> ---

Acked-by: Neal Cardwell <ncardwell@google.com>

Great. Thanks, Eric!

neal
patchwork-bot+netdevbpf@kernel.org April 26, 2024, 9:33 p.m. UTC | #2 
Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 25 Apr 2024 19:34:50 +0000 you wrote:
> I forgot to call tcp_skb_collapse_tstamp() in the
> case we consume the second skb in write queue.
> 
> Neal suggested to create a common helper used by tcp_mtu_probe()
> and tcp_grow_skb().
> 
> Fixes: 8ee602c63520 ("tcp: try to send bigger TSO packets")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Neal Cardwell <ncardwell@google.com>
> 
> [...]

Here is the summary with links:
  - [net-next] tcp: fix tcp_grow_skb() vs tstamps
    https://git.kernel.org/netdev/net-next/c/1bede0a12d3a

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index ce59e4499b66dfd2fe00c255c11187e3c08c5806..ef25556c48139c1904ac3fe6e484676ba10ba1bf 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2403,6 +2403,21 @@  static int tcp_clone_payload(struct sock *sk, struct sk_buff *to,
 	return 0;
 }
 
+/* tcp_mtu_probe() and tcp_grow_skb() can both eat an skb (src) if
+ * all its payload was moved to another one (dst).
+ * Make sure to transfer tcp_flags, eor, and tstamp.
+ */
+static void tcp_eat_one_skb(struct sock *sk,
+			    struct sk_buff *dst,
+			    struct sk_buff *src)
+{
+	TCP_SKB_CB(dst)->tcp_flags |= TCP_SKB_CB(src)->tcp_flags;
+	TCP_SKB_CB(dst)->eor = TCP_SKB_CB(src)->eor;
+	tcp_skb_collapse_tstamp(dst, src);
+	tcp_unlink_write_queue(src, sk);
+	tcp_wmem_free_skb(sk, src);
+}
+
 /* Create a new MTU probe if we are ready.
  * MTU probe is regularly attempting to increase the path MTU by
  * deliberately sending larger packets.  This discovers routing
@@ -2508,16 +2523,7 @@  static int tcp_mtu_probe(struct sock *sk)
 		copy = min_t(int, skb->len, probe_size - len);
 
 		if (skb->len <= copy) {
-			/* We've eaten all the data from this skb.
-			 * Throw it away. */
-			TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags;
-			/* If this is the last SKB we copy and eor is set
-			 * we need to propagate it to the new skb.
-			 */
-			TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor;
-			tcp_skb_collapse_tstamp(nskb, skb);
-			tcp_unlink_write_queue(skb, sk);
-			tcp_wmem_free_skb(sk, skb);
+			tcp_eat_one_skb(sk, nskb, skb);
 		} else {
 			TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags &
 						   ~(TCPHDR_FIN|TCPHDR_PSH);
@@ -2705,11 +2711,10 @@  static void tcp_grow_skb(struct sock *sk, struct sk_buff *skb, int amount)
 	TCP_SKB_CB(next_skb)->seq += nlen;
 
 	if (!next_skb->len) {
+		/* In case FIN is set, we need to update end_seq */
 		TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq;
-		TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor;
-		TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags;
-		tcp_unlink_write_queue(next_skb, sk);
-		tcp_wmem_free_skb(sk, next_skb);
+
+		tcp_eat_one_skb(sk, skb, next_skb);
 	}
 }