device-mapper-multipath/0152-multipathd-remove-thread-from-mpath_pr_event_handle.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Benjamin Marzinski <bmarzins@redhat.com>
Date: Mon, 16 Jun 2025 19:25:50 -0400
Subject: [PATCH] multipathd: remove thread from mpath_pr_event_handle

mpath_pr_event_handle() creates a separate thread to do the persistent
reservation work, but it doesn't take any advantage of the work being
done in another thread. Merge mpath_pr_event_handle() and
mpath_pr_event_handler_fn() into a single function with no separate
thread.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 multipathd/main.c | 49 ++++++++++++-----------------------------------
 multipathd/main.h |  3 ---
 2 files changed, 12 insertions(+), 40 deletions(-)

diff --git a/multipathd/main.c b/multipathd/main.c
index 4119ad79..3f4b8ff6 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -90,6 +90,8 @@
 #define CMDSIZE 160
 #define MSG_SIZE 32
 
+static void mpath_pr_event_handle(struct path *pp);
+
 #define LOG_MSG(lvl, pp)					\
 do {								\
 	if (pp->mpp && checker_selected(&pp->checker) &&	\
@@ -3722,17 +3724,24 @@ main (int argc, char *argv[])
 		return (child(NULL));
 }
 
-void *  mpath_pr_event_handler_fn (void * pathp )
+static void mpath_pr_event_handle(struct path *pp)
 {
 	struct multipath * mpp;
 	unsigned int i;
 	int ret, isFound;
-	struct path * pp = (struct path *)pathp;
 	struct prout_param_descriptor *param;
 	struct prin_resp *resp;
 
-	rcu_register_thread();
 	mpp = pp->mpp;
+	if (pp->bus != SYSFS_BUS_SCSI) {
+		mpp->prflag = PRFLAG_UNSET;
+		return;
+	}
+
+	if (!get_be64(mpp->reservation_key)) {
+		mpp->prflag = PRFLAG_UNSET;
+		return;
+	}
 
 	resp = mpath_alloc_prin_response(MPATH_PRIN_RKEY_SA);
 	if (!resp){
@@ -3799,38 +3808,4 @@ void *  mpath_pr_event_handler_fn (void * pathp )
 out:
 	if (resp)
 		free(resp);
-	rcu_unregister_thread();
-	return NULL;
-}
-
-int mpath_pr_event_handle(struct path *pp)
-{
-	pthread_t thread;
-	int rc;
-	pthread_attr_t attr;
-	struct multipath * mpp;
-
-	if (pp->bus != SYSFS_BUS_SCSI)
-		goto no_pr;
-
-	mpp = pp->mpp;
-
-	if (!get_be64(mpp->reservation_key))
-		goto no_pr;
-
-	pthread_attr_init(&attr);
-	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
-
-	rc = pthread_create(&thread, NULL , mpath_pr_event_handler_fn, pp);
-	if (rc) {
-		condlog(0, "%s: ERROR; return code from pthread_create() is %d", pp->dev, rc);
-		return -1;
-	}
-	pthread_attr_destroy(&attr);
-	rc = pthread_join(thread, NULL);
-	return 0;
-
-no_pr:
-	pp->mpp->prflag = PRFLAG_UNSET;
-	return 0;
 }
diff --git a/multipathd/main.h b/multipathd/main.h
index 4138faa4..897051e0 100644
--- a/multipathd/main.h
+++ b/multipathd/main.h
@@ -52,10 +52,7 @@ void dumpHex(const char * , int len, int no_ascii);
 int prout_do_scsi_ioctl(char * , int rq_servact, int rq_scope,
 			unsigned int rq_type,
 			struct prout_param_descriptor *param, int noisy);
-int mpath_pr_event_handle(struct path *pp);
-void * mpath_pr_event_handler_fn (void * );
 int update_map_pr(struct multipath *mpp);
-void * mpath_pr_event_handler_fn (void * pathp );
 void handle_signals(bool);
 int __setup_multipath (struct vectors * vecs, struct multipath * mpp,
 		       int reset);