From 1f9e26e221a41542563834222c4ec8399be1908f Mon Sep 17 00:00:00 2001
From: Xadhoom <>
Date: Sun, 7 Mar 2021 14:03:07 +0000
Subject: [PATCH] Use reentrant mutex for core thread

---
 ports/unix/port/sys_arch.c | 12 ++++++++++--
 ports/win32/sys_arch.c     |  6 +++++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/ports/unix/port/sys_arch.c b/ports/unix/port/sys_arch.c
index 3336539..99d2ccf 100644
--- a/ports/unix/port/sys_arch.c
+++ b/ports/unix/port/sys_arch.c
@@ -204,15 +204,19 @@ sys_thread_new(const char *name, lwip_thread_fn function, void *arg, int stacksi
 
 #if LWIP_TCPIP_CORE_LOCKING
 static pthread_t lwip_core_lock_holder_thread_id;
+static int lwip_core_lock_holder_reclevel = 0;
 void sys_lock_tcpip_core(void)
 {
   sys_mutex_lock(&lock_tcpip_core);
   lwip_core_lock_holder_thread_id = pthread_self();
+  lwip_core_lock_holder_reclevel += 1;
 }
 
 void sys_unlock_tcpip_core(void)
 {
-  lwip_core_lock_holder_thread_id = 0;
+  lwip_core_lock_holder_reclevel -= 1;
+  if(!lwip_core_lock_holder_reclevel)
+    lwip_core_lock_holder_thread_id = 0;
   sys_mutex_unlock(&lock_tcpip_core);
 }
 #endif /* LWIP_TCPIP_CORE_LOCKING */
@@ -591,10 +595,14 @@ err_t
 sys_mutex_new(struct sys_mutex **mutex)
 {
   struct sys_mutex *mtx;
+  pthread_mutexattr_t attr;
 
   mtx = (struct sys_mutex *)malloc(sizeof(struct sys_mutex));
+
   if (mtx != NULL) {
-    pthread_mutex_init(&(mtx->mutex), NULL);
+    pthread_mutexattr_init(&attr);
+    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+    pthread_mutex_init(&(mtx->mutex), &attr);
     *mutex = mtx;
     return ERR_OK;
   }
diff --git a/ports/win32/sys_arch.c b/ports/win32/sys_arch.c
index 1a37f14..cbdfd33 100644
--- a/ports/win32/sys_arch.c
+++ b/ports/win32/sys_arch.c
@@ -471,18 +471,22 @@ sys_thread_new(const char *name, lwip_thread_fn function, void *arg, int stacksi
 #if LWIP_TCPIP_CORE_LOCKING
 
 static DWORD lwip_core_lock_holder_thread_id;
+static int lwip_core_lock_holder_reclevel = 0;
 
 void
 sys_lock_tcpip_core(void)
 {
   sys_mutex_lock(&lock_tcpip_core);
   lwip_core_lock_holder_thread_id = GetCurrentThreadId();
+  lwip_core_lock_holder_reclevel += 1;
 }
 
 void
 sys_unlock_tcpip_core(void)
 {
-  lwip_core_lock_holder_thread_id = 0;
+  lwip_core_lock_holder_reclevel -= 1;
+  if(!lwip_core_lock_holder_reclevel)
+    lwip_core_lock_holder_thread_id = 0;
   sys_mutex_unlock(&lock_tcpip_core);
 }
 #endif /* LWIP_TCPIP_CORE_LOCKING */