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From: Bruce Richardson <bruce.richardson@intel.com>
To: dev@dpdk.org
Cc: Ciara Power <ciara.power@intel.com>,
 David Marchand <david.marchand@redhat.com>,
 Anatoly Burakov <anatoly.burakov@intel.com>,
 Kevin Traynor <ktraynor@redhat.com>,
 Bruce Richardson <bruce.richardson@intel.com>
Date: Fri,  1 Oct 2021 17:22:32 +0100
Message-Id: <20211001162235.389781-3-bruce.richardson@intel.com>
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 <20211001162235.389781-1-bruce.richardson@intel.com>
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Subject: [dpdk-dev] [PATCH v5 2/5] telemetry: fix deletion of active sockets
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When DPDK is run with --in-memory mode, multiple processes can run
simultaneously using the same runtime dir. This leads to each process,
as it starts up, removing the telemetry socket of another process,
giving unexpected behaviour.

This patch changes that behaviour to first check if the existing socket
is active. If not, it's an old socket to be cleaned up and can be
removed. If it is active, telemetry initialization fails and an error
message is printed out giving instructions on how to remove the error;
either by using file-prefix to have a different runtime dir (and
therefore socket path) or by disabling telemetry if it not needed.

Fixes: 6dd571fd07c3 ("telemetry: introduce new functionality")

Reported-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Ciara Power <ciara.power@intel.com>
---
 lib/telemetry/telemetry.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/lib/telemetry/telemetry.c b/lib/telemetry/telemetry.c
index 48f4c7ba46..6676322991 100644
--- a/lib/telemetry/telemetry.c
+++ b/lib/telemetry/telemetry.c
@@ -457,15 +457,30 @@ create_socket(char *path)
 
 	struct sockaddr_un sun = {.sun_family = AF_UNIX};
 	strlcpy(sun.sun_path, path, sizeof(sun.sun_path));
-	unlink(sun.sun_path);
+
 	if (bind(sock, (void *) &sun, sizeof(sun)) < 0) {
 		struct stat st;
 
-		TMTY_LOG(ERR, "Error binding socket: %s\n", strerror(errno));
-		if (stat(socket_dir, &st) < 0 || !S_ISDIR(st.st_mode))
+		/* first check if we have a runtime dir */
+		if (stat(socket_dir, &st) < 0 || !S_ISDIR(st.st_mode)) {
 			TMTY_LOG(ERR, "Cannot access DPDK runtime directory: %s\n", socket_dir);
-		sun.sun_path[0] = 0;
-		goto error;
+			goto error;
+		}
+
+		/* check if current socket is active */
+		if (connect(sock, (void *)&sun, sizeof(sun)) == 0) {
+			TMTY_LOG(ERR, "Error binding telemetry socket, path already in use\n");
+			TMTY_LOG(ERR, "Use '--file-prefix' to select a different socket path, or '--no-telemetry' to disable\n");
+			path[0] = 0;
+			goto error;
+		}
+
+		/* socket is not active, delete and attempt rebind */
+		unlink(sun.sun_path);
+		if (bind(sock, (void *) &sun, sizeof(sun)) < 0) {
+			TMTY_LOG(ERR, "Error binding socket: %s\n", strerror(errno));
+			goto error;
+		}
 	}
 
 	if (listen(sock, 1) < 0) {
-- 
2.30.2