[PATCH 23/35] monitor: handle restart of pending discoveries

[mwilck@suse.com]

From: Martin Wilck <mwilck@suse.com>

If a new discovery event is received while a discovery task is
running, no new task should be started in parallel to the previous
one. Rather, we should note that another event has happened,
and restart the discovery after the current task has finished.

There is no need to remember more than one pending discovery.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 monitor.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 9 deletions(-)

diff --git a/monitor.c b/monitor.c
index 419c5f5..b44ff7a 100644
--- a/monitor.c
+++ b/monitor.c
@@ -36,6 +36,7 @@
 #include "util/argconfig.h"
 #include "fabrics.h"
 #include "monitor.h"
+#include "conn-db.h"
 #define LOG_FUNCNAME 1
 #include "log.h"
 
@@ -199,12 +200,22 @@ static int monitor_get_fc_uev_props(struct udev_device *ud,
 	return 0;
 }
 
-static int monitor_discovery(char *transport, char *traddr, char *trsvcid,
-			     char *host_traddr)
+static int monitor_discovery(const char *transport, const char *traddr,
+			     const char *trsvcid, const char *host_traddr)
 {
 	char argstr[BUF_SIZE];
 	pid_t pid;
-	int rc;
+	int rc, db_rc;
+	struct nvme_connection *co = NULL;
+
+	db_rc = conndb_add(transport, traddr, trsvcid, host_traddr, &co);
+	if (db_rc != 0 && db_rc != -EEXIST)
+		return db_rc;
+
+	if (co->status == CS_DISC_RUNNING) {
+		co->discovery_pending = 1;
+		return -EAGAIN;
+	}
 
 	pid = fork();
 	if (pid == -1) {
@@ -212,17 +223,26 @@ static int monitor_discovery(char *transport, char *traddr, char *trsvcid,
 		return -errno;
 	} else if (pid > 0) {
 		log(LOG_DEBUG, "started discovery task %ld\n", (long)pid);
+
+		co->discovery_pending = 0;
+		co->status = CS_DISC_RUNNING;
+		co->discovery_task = pid;
+
 		return 0;
 	}
 
 	child_reset_signals();
 
-	log(LOG_NOTICE, "starting %s discovery for %s==>%s(%s)\n",
-	    transport, host_traddr, traddr, trsvcid ? trsvcid : "none");
+	log(LOG_NOTICE, "starting discovery for <%s>: %s ==> %s(%s) in state %s\n",
+	    transport, host_traddr, traddr,
+	    trsvcid && *trsvcid ? trsvcid : "none",
+	    conn_status_str(co->status));
+
+
 	cfg.nqn = NVME_DISC_SUBSYS_NAME;
 	cfg.transport = transport;
 	cfg.traddr = traddr;
-	cfg.trsvcid = trsvcid;
+	cfg.trsvcid = trsvcid && *trsvcid ? trsvcid : NULL;
 	cfg.host_traddr = host_traddr;
 	/* Without the following, the kernel returns EINVAL */
 	cfg.tos = -1;
@@ -351,6 +371,7 @@ static void monitor_handle_uevents(struct udev_monitor *monitor)
 static void handle_sigchld(void)
 {
 	while (true) {
+	struct nvme_connection *co;
 		int wstatus;
 		pid_t pid;
 
@@ -365,14 +386,33 @@ static void handle_sigchld(void)
 		default:
 			break;
 		}
-		if (!WIFEXITED(wstatus))
+		co = conndb_find_by_pid(pid);
+		if (!co) {
+			log(LOG_ERR, "no connection found for discovery task %ld\n",
+			    (long)pid);
+			continue;
+		}
+		if (!WIFEXITED(wstatus)) {
 			log(LOG_WARNING, "child %ld didn't exit normally\n",
 			    (long)pid);
-		else if (WEXITSTATUS(wstatus) != 0)
+			co->status = CS_FAILED;
+		} else if (WEXITSTATUS(wstatus) != 0) {
 			log(LOG_NOTICE, "child %ld exited with status \"%s\"\n",
 			    (long)pid, strerror(WEXITSTATUS(wstatus)));
-		else
+			co->status = CS_FAILED;
+			co->did_discovery = 1;
+			co->discovery_result = WEXITSTATUS(wstatus);
+		} else {
 			log(LOG_DEBUG, "child %ld exited normally\n", (long)pid);
+			co->status = CS_ONLINE;
+			co->successful_discovery = co->did_discovery = 1;
+			co->discovery_result = 0;
+		}
+		if (co->discovery_pending) {
+			log(LOG_NOTICE, "new discovery pending - restarting\n");
+			monitor_discovery(co->transport, co->traddr,
+					  co->trsvcid, co->host_traddr);
+		}
 	};
 }
 
-- 
2.29.2


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