FAILED: patch "[PATCH] mptcp: fix missing wakeup" failed to apply to 5.11-stable tree

The patch below does not apply to the 5.11-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 417789df4a03bc820b082bcc503f0d4c5e4704b9 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <[email protected]>
Date: Thu, 4 Mar 2021 13:32:15 -0800
Subject: [PATCH] mptcp: fix missing wakeup

__mptcp_clean_una() can free write memory and should wake-up user-space processes when needed.

When such function is invoked by the MPTCP receive path, the wakeup is not needed, as the TCP stack will later trigger subflow_write_space which will do the wakeup as needed.

Other __mptcp_clean_una() call sites need an additional wakeup check Let's bundle the relevant code in a new helper and use it.

index d2a2169e6d9e..76958570ae7f 100644
@@ -1061,6 +1061,12 @@ static void __mptcp_clean_una(struct sock *sk)
 	}
 }
 
+static void __mptcp_clean_una_wakeup(struct sock *sk)
+{
+	__mptcp_clean_una(sk);
+	mptcp_write_space(sk);
+}
+
 static void mptcp_enter_memory_pressure(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow;

@@ -2270,7 +2276,7 @@ static void __mptcp_retrans(struct sock *sk)
 	struct sock *ssk;
 	int ret;
 
-	__mptcp_clean_una(sk);
+	__mptcp_clean_una_wakeup(sk);
 	dfrag = mptcp_rtx_head(sk);
 	if (!dfrag)
 		return;

@@ -2983,7 +2989,7 @@ static void mptcp_release_cb(struct sock *sk)
 	}
 
 	if (test_and_clear_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags))
-		__mptcp_clean_una(sk);
+		__mptcp_clean_una_wakeup(sk);
 	if (test_and_clear_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->flags))
 		__mptcp_error_report(sk);