From 471013f7e09635339f8165b3bfd75f1ee6384b61 Mon Sep 17 00:00:00 2001
From: Ivan Grokhotkov <ivan@espressif.com>
Date: Mon, 4 Mar 2019 16:59:09 +0800
Subject: [PATCH] mdns: use binary semaphore instead of mutex when searching

mdns_search_once_t::lock is used to synchronize tasks (taken by one
task and given by the other) so it should not be a mutex.
Convert to semaphore, and rename to indicate its purpose.
---
 components/mdns/mdns.c                         | 14 ++++++--------
 components/mdns/private_include/mdns_private.h |  5 +----
 2 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/components/mdns/mdns.c b/components/mdns/mdns.c
index e524a3130..cf9d0c23a 100644
--- a/components/mdns/mdns.c
+++ b/components/mdns/mdns.c
@@ -3098,7 +3098,7 @@ static void _mdns_search_free(mdns_search_once_t * search)
     free(search->instance);
     free(search->service);
     free(search->proto);
-    vSemaphoreDelete(search->lock);
+    vSemaphoreDelete(search->done_semaphore);
     free(search);
 }
 
@@ -3114,8 +3114,8 @@ static mdns_search_once_t * _mdns_search_init(const char * name, const char * se
     }
     memset(search, 0, sizeof(mdns_search_once_t));
 
-    search->lock = xSemaphoreCreateMutex();
-    if (!search->lock) {
+    search->done_semaphore = xSemaphoreCreateBinary();
+    if (!search->done_semaphore) {
         free(search);
         return NULL;
     }
@@ -3154,8 +3154,6 @@ static mdns_search_once_t * _mdns_search_init(const char * name, const char * se
     search->started_at = xTaskGetTickCount() * portTICK_PERIOD_MS;
     search->next = NULL;
 
-    xSemaphoreTake(search->lock, 0);
-
     return search;
 }
 
@@ -3166,7 +3164,7 @@ static void _mdns_search_finish(mdns_search_once_t * search)
 {
     search->state = SEARCH_OFF;
     queueDetach(mdns_search_once_t, _mdns_server->search_once, search);
-    xSemaphoreGive(search->lock);
+    xSemaphoreGive(search->done_semaphore);
 }
 
 /**
@@ -4192,7 +4190,7 @@ void mdns_free()
         free(h->instance);
         free(h->service);
         free(h->proto);
-        vSemaphoreDelete(h->lock);
+        vSemaphoreDelete(h->done_semaphore);
         if (h->result) {
             mdns_query_results_free(h->result);
         }
@@ -4582,7 +4580,7 @@ esp_err_t mdns_query(const char * name, const char * service, const char * proto
         _mdns_search_free(search);
         return ESP_ERR_NO_MEM;
     }
-    xSemaphoreTake(search->lock, portMAX_DELAY);
+    xSemaphoreTake(search->done_semaphore, portMAX_DELAY);
 
     *results = search->result;
     _mdns_search_free(search);
diff --git a/components/mdns/private_include/mdns_private.h b/components/mdns/private_include/mdns_private.h
index da5162348..269a5695d 100644
--- a/components/mdns/private_include/mdns_private.h
+++ b/components/mdns/private_include/mdns_private.h
@@ -112,9 +112,6 @@
 #define PCB_STATE_IS_ANNOUNCING(s) (s->state > PCB_PROBE_3 && s->state < PCB_RUNNING)
 #define PCB_STATE_IS_RUNNING(s) (s->state == PCB_RUNNING)
 
-#define MDNS_SEARCH_LOCK()      xSemaphoreTake(_mdns_server->search.lock, portMAX_DELAY)
-#define MDNS_SEARCH_UNLOCK()    xSemaphoreGive(_mdns_server->search.lock)
-
 #ifndef HOOK_MALLOC_FAILED
 #define HOOK_MALLOC_FAILED  ESP_LOGE(TAG, "Cannot allocate memory (line: %d, free heap: %d bytes)", __LINE__, esp_get_free_heap_size());
 #endif
@@ -316,7 +313,7 @@ typedef struct mdns_search_once_s {
     uint32_t started_at;
     uint32_t sent_at;
     uint32_t timeout;
-    SemaphoreHandle_t lock;
+    SemaphoreHandle_t done_semaphore;
     uint16_t type;
     uint8_t max_results;
     uint8_t num_results;