linux-kernel - [PATCH V2] net: qrtr: Do not do DEL_SERVER broadcast after DEL

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Message-ID: <1680248937-16617-1-git-send-email-quic_srichara@quicinc.com>
Date:   Fri, 31 Mar 2023 13:18:57 +0530
From:   Sricharan Ramabadhran <quic_srichara@...cinc.com>
To:     <mani@...nel.org>, <manivannan.sadhasivam@...aro.org>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <linux-arm-msm@...r.kernel.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH V2] net: qrtr: Do not do DEL_SERVER broadcast after DEL_CLIENT

On the remote side, when QRTR socket is removed, af_qrtr will call
qrtr_port_remove() which broadcasts the DEL_CLIENT packet to all neighbours
including local NS. NS upon receiving the DEL_CLIENT packet, will remove
the lookups associated with the node:port and broadcasts the DEL_SERVER
packet.

But on the host side, due to the arrival of the DEL_CLIENT packet, the NS
would've already deleted the server belonging to that port. So when the
remote's NS again broadcasts the DEL_SERVER for that port, it throws below
error message on the host:

"failed while handling packet from 2:-2"

So fix this error by not broadcasting the DEL_SERVER packet when the
DEL_CLIENT packet gets processed."

Fixes: 0c2204a4ad71 ("net: qrtr: Migrate nameservice to kernel from userspace")
Signed-off-by: Sricharan Ramabadhran <quic_srichara@...cinc.com>
Signed-off-by: Ram Kumar Dharuman <quic_ramd@...cinc.com>
---
[v2] Fixed comments from Manivannan and Jakub Kicinski
Note: Functionally tested on 5.4 and compile tested on 6.3 TOT

 net/qrtr/ns.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
index 722936f..0f25a38 100644
--- a/net/qrtr/ns.c
+++ b/net/qrtr/ns.c
@@ -274,7 +274,7 @@ static struct qrtr_server *server_add(unsigned int service,
 	return NULL;
 }
 
-static int server_del(struct qrtr_node *node, unsigned int port)
+static int server_del(struct qrtr_node *node, unsigned int port, bool bcast)
 {
 	struct qrtr_lookup *lookup;
 	struct qrtr_server *srv;
@@ -287,7 +287,7 @@ static int server_del(struct qrtr_node *node, unsigned int port)
 	radix_tree_delete(&node->servers, port);
 
 	/* Broadcast the removal of local servers */
-	if (srv->node == qrtr_ns.local_node)
+	if (srv->node == qrtr_ns.local_node && bcast)
 		service_announce_del(&qrtr_ns.bcast_sq, srv);
 
 	/* Announce the service's disappearance to observers */
@@ -373,7 +373,7 @@ static int ctrl_cmd_bye(struct sockaddr_qrtr *from)
 		}
 		slot = radix_tree_iter_resume(slot, &iter);
 		rcu_read_unlock();
-		server_del(node, srv->port);
+		server_del(node, srv->port, true);
 		rcu_read_lock();
 	}
 	rcu_read_unlock();
@@ -459,10 +459,13 @@ static int ctrl_cmd_del_client(struct sockaddr_qrtr *from,
 		kfree(lookup);
 	}
 
-	/* Remove the server belonging to this port */
+	/* Remove the server belonging to this port but don't broadcast
+	 * DEL_SERVER. Neighbours would've already removed the server belonging
+	 * to this port due to the DEL_CLIENT broadcast from qrtr_port_remove().
+	 */
 	node = node_get(node_id);
 	if (node)
-		server_del(node, port);
+		server_del(node, port, false);
 
 	/* Advertise the removal of this client to all local servers */
 	local_node = node_get(qrtr_ns.local_node);
@@ -567,7 +570,7 @@ static int ctrl_cmd_del_server(struct sockaddr_qrtr *from,
 	if (!node)
 		return -ENOENT;
 
-	return server_del(node, port);
+	return server_del(node, port, true);
 }
 
 static int ctrl_cmd_new_lookup(struct sockaddr_qrtr *from,
-- 
2.7.4