mptcp: pr_debug: add missing \n at the end

pr_debug() have been added in various places in MPTCP code to help
developers to debug some situations. With the dynamic debug feature, it
is easy to enable all or some of them, and asks users to reproduce
issues with extra debug.

Many of these pr_debug() don't end with a new line, while no 'pr_cont()'
are used in MPTCP code. So the goal was not to display multiple debug
messages on one line: they were then not missing the '\n' on purpose.
Not having the new line at the end causes these messages to be printed
with a delay, when something else needs to be printed. This issue is not
visible when many messages need to be printed, but it is annoying and
confusing when only specific messages are expected, e.g.

  # echo "func mptcp_pm_add_addr_echoed +fmp" \
        > /sys/kernel/debug/dynamic_debug/control
  # ./mptcp_join.sh "signal address"; \
        echo "$(awk '{print $1}' /proc/uptime) - end"; \
        sleep 5s; \
        echo "$(awk '{print $1}' /proc/uptime) - restart"; \
        ./mptcp_join.sh "signal address"
  013 signal address
      (...)
  10.75 - end
  15.76 - restart
  013 signal address
  [  10.367935] mptcp:mptcp_pm_add_addr_echoed: MPTCP: msk=(...)
      (...)

  => a delay of 5 seconds: printed with a 10.36 ts, but after 'restart'
     which was printed at the 15.76 ts.

The 'Fixes' tag here below points to the first pr_debug() used without
'\n' in net/mptcp. This patch could be split in many small ones, with
different Fixes tag, but it doesn't seem worth it, because it is easy to
re-generate this patch with this simple 'sed' command:

  git grep -l pr_debug -- net/mptcp |
    xargs sed -i "s/\(pr_debug(\".*[^n]\)\(\"[,)]\)/\1\\\n\2/g"

So in case of conflicts, simply drop the modifications, and launch this
command.

Fixes: f870fa0b5768 ("mptcp: Add MPTCP socket stubs")
Cc: stable@vger.kernel.org
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240826-net-mptcp-close-extra-sf-fin-v1-4-905199fe1172@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index a1c1b0ff1ce1..240d7c2ea551 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1177,7 +1177,7 @@ static inline bool mptcp_check_fallback(const struct sock *sk)
 static inline void __mptcp_do_fallback(struct mptcp_sock *msk)
 {
 	if (__mptcp_check_fallback(msk)) {
-		pr_debug("TCP fallback already done (msk=%p)", msk);
+		pr_debug("TCP fallback already done (msk=%p)\n", msk);
 		return;
 	}
 	set_bit(MPTCP_FALLBACK_DONE, &msk->flags);
@@ -1213,7 +1213,7 @@ static inline void mptcp_do_fallback(struct sock *ssk)
 	}
 }
 
-#define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=%p)", __func__, a)
+#define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=%p)\n", __func__, a)
 
 static inline bool mptcp_check_infinite_map(struct sk_buff *skb)
 {