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libnbd/SOURCES/0003-generator-Print-a-bett...

49 lines
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From f094472efcf34cea8bf1f02a1c5c9442ffc4ca53 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Thu, 4 Feb 2021 18:02:46 +0000
Subject: [PATCH] generator: Print a better error message if connect(2) returns
EAGAIN.
The new error message is:
nbd_connect_unix: connect: server backlog overflowed, see https://bugzilla.redhat.com/1925045: Resource temporarily unavailable
Fixes: https://bugzilla.redhat.com/1925045
Thanks: Xin Long, Lukas Doktor, Eric Blake
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
(cherry picked from commit 85ed74960a658a82d7b61b0be07f43d1b2dcede9)
---
generator/states-connect.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/generator/states-connect.c b/generator/states-connect.c
index 03b34c7..98c26e5 100644
--- a/generator/states-connect.c
+++ b/generator/states-connect.c
@@ -70,6 +70,22 @@ STATE_MACHINE {
if (r == 0 || (r == -1 && errno == EINPROGRESS))
return 0;
assert (r == -1);
+#ifdef __linux__
+ if (errno == EAGAIN && family == AF_UNIX) {
+ /* This can happen on Linux when connecting to a Unix domain
+ * socket, if the server's backlog is full. Unfortunately there
+ * is nothing good we can do on the client side when this happens
+ * since any solution would involve sleeping or busy-waiting. The
+ * only solution is on the server side, increasing the backlog.
+ * But at least improve the error message.
+ * https://bugzilla.redhat.com/1925045
+ */
+ SET_NEXT_STATE (%.DEAD);
+ set_error (errno, "connect: server backlog overflowed, "
+ "see https://bugzilla.redhat.com/1925045");
+ return 0;
+ }
+#endif
SET_NEXT_STATE (%.DEAD);
set_error (errno, "connect");
return 0;
--
2.31.1