4.9-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ Upstream commit 69ffaebb90369ce08657b5aea4896777b9d6e8fc ]
rxrpc_get_client_conn() adds a new call to the front of the waiting_calls queue if the connection it's going to use already exists. This is bad as it allows calls to get starved out.
Fix this by adding to the tail instead.
Also change the other enqueue point in the same function to put it on the front (ie. when we have a new connection). This makes the point that in the case of a new connection the new call goes at the front (though it doesn't actually matter since the queue should be unoccupied).
Fixes: 45025bceef17 ("rxrpc: Improve management and caching of client connection objects") Signed-off-by: David Howells dhowells@redhat.com Reviewed-by: Marc Dionne marc.dionne@auristor.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/rxrpc/conn_client.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/rxrpc/conn_client.c +++ b/net/rxrpc/conn_client.c @@ -355,7 +355,7 @@ static int rxrpc_get_client_conn(struct * normally have to take channel_lock but we do this before anyone else * can see the connection. */ - list_add_tail(&call->chan_wait_link, &candidate->waiting_calls); + list_add(&call->chan_wait_link, &candidate->waiting_calls);
if (cp->exclusive) { call->conn = candidate; @@ -430,7 +430,7 @@ found_extant_conn: spin_lock(&conn->channel_lock); call->conn = conn; call->security_ix = conn->security_ix; - list_add(&call->chan_wait_link, &conn->waiting_calls); + list_add_tail(&call->chan_wait_link, &conn->waiting_calls); spin_unlock(&conn->channel_lock); _leave(" = 0 [extant %d]", conn->debug_id); return 0;