From: Florian Westphal <fw@strlen.de>
Date: Tue, 25 Aug 2020 23:31:05 +0000 (+0200)
Subject: mptcp: free acked data before waiting for more memory
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1cec170d458b1d18f6f1654ca84c0804a701c5ef;p=linux.git

mptcp: free acked data before waiting for more memory

After subflow lock is dropped, more wmem might have been made available.

This fixes a deadlock in mptcp_connect.sh 'mmap' mode: wmem is exhausted.
But as the mptcp socket holds on to already-acked data (for retransmit)
no wakeup will occur.

Using 'goto restart' calls mptcp_clean_una(sk) which will free pages
that have been acked completely in the mean time.

Fixes: fb529e62d3f3 ("mptcp: break and restart in case mptcp sndbuf is full")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 1aad411a0e461..8ccd4a151dcb7 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -892,7 +892,6 @@ restart:
 		goto out;
 	}
 
-wait_for_sndbuf:
 	__mptcp_flush_join_list(msk);
 	ssk = mptcp_subflow_get_send(msk);
 	while (!sk_stream_memory_free(sk) ||
@@ -982,7 +981,7 @@ wait_for_sndbuf:
 				 */
 				mptcp_set_timeout(sk, ssk);
 				release_sock(ssk);
-				goto wait_for_sndbuf;
+				goto restart;
 			}
 		}
 	}