From 3f45ed2467270fccd8f76729a23c19243502b8d7 Mon Sep 17 00:00:00 2001
From: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Date: Tue, 27 Apr 2021 00:20:54 +0900
Subject: [PATCH] thread: Change if-else_if to switch-case blocks of
 thread_execute_poller()

Change if - else if - else blocks of thread_execute_poller() and
thread_execute_timed_poller() to switch - cases blocks and specify
possible states explicitly in these switch - cases blocks.

The code will be simpler and clarified, and then the following patches
will be easier.

Signed-off-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Change-Id: I2e283894f5d69e1bd67466ae070c5b8bb9014616
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/7664
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>
---
 lib/thread/thread.c | 44 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 36 insertions(+), 8 deletions(-)

diff --git a/lib/thread/thread.c b/lib/thread/thread.c
index ea8fe9c60..231a205d1 100644
--- a/lib/thread/thread.c
+++ b/lib/thread/thread.c
@@ -608,15 +608,21 @@ thread_execute_poller(struct spdk_thread *thread, struct spdk_poller *poller)
 {
 	int rc;
 
-	if (poller->state == SPDK_POLLER_STATE_UNREGISTERED) {
+	switch (poller->state) {
+	case SPDK_POLLER_STATE_UNREGISTERED:
 		TAILQ_REMOVE(&thread->active_pollers, poller, tailq);
 		free(poller);
 		return 0;
-	} else if (poller->state == SPDK_POLLER_STATE_PAUSING) {
+	case SPDK_POLLER_STATE_PAUSING:
 		TAILQ_REMOVE(&thread->active_pollers, poller, tailq);
 		TAILQ_INSERT_TAIL(&thread->paused_pollers, poller, tailq);
 		poller->state = SPDK_POLLER_STATE_PAUSED;
 		return 0;
+	case SPDK_POLLER_STATE_WAITING:
+		break;
+	default:
+		assert(false);
+		break;
 	}
 
 	poller->state = SPDK_POLLER_STATE_RUNNING;
@@ -633,11 +639,19 @@ thread_execute_poller(struct spdk_thread *thread, struct spdk_poller *poller)
 	}
 #endif
 
-	if (poller->state == SPDK_POLLER_STATE_UNREGISTERED) {
+	switch (poller->state) {
+	case SPDK_POLLER_STATE_UNREGISTERED:
 		TAILQ_REMOVE(&thread->active_pollers, poller, tailq);
 		free(poller);
-	} else if (poller->state != SPDK_POLLER_STATE_PAUSED) {
+		break;
+	case SPDK_POLLER_STATE_PAUSED:
+		break;
+	case SPDK_POLLER_STATE_RUNNING:
 		poller->state = SPDK_POLLER_STATE_WAITING;
+		break;
+	default:
+		assert(false);
+		break;
 	}
 
 	return rc;
@@ -649,15 +663,21 @@ thread_execute_timed_poller(struct spdk_thread *thread, struct spdk_poller *poll
 {
 	int rc;
 
-	if (poller->state == SPDK_POLLER_STATE_UNREGISTERED) {
+	switch (poller->state) {
+	case SPDK_POLLER_STATE_UNREGISTERED:
 		TAILQ_REMOVE(&thread->timed_pollers, poller, tailq);
 		free(poller);
 		return 0;
-	} else if (poller->state == SPDK_POLLER_STATE_PAUSING) {
+	case SPDK_POLLER_STATE_PAUSING:
 		TAILQ_REMOVE(&thread->timed_pollers, poller, tailq);
 		TAILQ_INSERT_TAIL(&thread->paused_pollers, poller, tailq);
 		poller->state = SPDK_POLLER_STATE_PAUSED;
 		return 0;
+	case SPDK_POLLER_STATE_WAITING:
+		break;
+	default:
+		assert(false);
+		break;
 	}
 
 	poller->state = SPDK_POLLER_STATE_RUNNING;
@@ -674,13 +694,21 @@ thread_execute_timed_poller(struct spdk_thread *thread, struct spdk_poller *poll
 	}
 #endif
 
-	if (poller->state == SPDK_POLLER_STATE_UNREGISTERED) {
+	switch (poller->state) {
+	case SPDK_POLLER_STATE_UNREGISTERED:
 		TAILQ_REMOVE(&thread->timed_pollers, poller, tailq);
 		free(poller);
-	} else if (poller->state != SPDK_POLLER_STATE_PAUSED) {
+		break;
+	case SPDK_POLLER_STATE_PAUSED:
+		break;
+	case SPDK_POLLER_STATE_RUNNING:
 		poller->state = SPDK_POLLER_STATE_WAITING;
 		TAILQ_REMOVE(&thread->timed_pollers, poller, tailq);
 		poller_insert_timer(thread, poller, now);
+		break;
+	default:
+		assert(false);
+		break;
 	}
 
 	return rc;