From d7deb3fbac6e88d30f9f0295b1737e6850b847a7 Mon Sep 17 00:00:00 2001
From: zhushengle <zhushengle@huawei.com>
Date: Fri, 13 Aug 2021 10:03:31 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20=E8=BF=9B=E7=A8=8B=E9=80=80=E5=87=BA?=
 =?UTF-8?q?=E9=9D=99=E6=80=81=E9=97=AE=E9=A2=98?=
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问题描述：
    进程在退出过程中，拿到了init_fini_lock锁后被信号打断，
收到退出信号，再次调用exit函数进入进程退出流程，造成死锁

解决方案：
    在libc中添加exit字段，在进程退出时将该字段表示进程已经在退出，
若再次进入退出流程，则直接退出，由第一个执行退出流程的线程继续执行
退出流程。并且在退出时屏蔽信号，避免退出流程被频繁打断。
Close #I43V23
Signed-off-by: zhushengle <zhushengle@huawei.com>

Change-Id: I57b60391267d50c8eb89fc115a26229461bb4ed4
---
 porting/liteos_a/user/src/exit/exit.c       | 40 +++++++++++++++++++++
 porting/liteos_a/user/src/internal/libc.h   |  1 +
 porting/liteos_a/user/src/process/fork.c    |  1 +
 porting/liteos_a/user_debug/src/exit/exit.c |  7 ++++
 4 files changed, 49 insertions(+)
 create mode 100644 porting/liteos_a/user/src/exit/exit.c

diff --git a/porting/liteos_a/user/src/exit/exit.c b/porting/liteos_a/user/src/exit/exit.c
new file mode 100644
index 00000000..5001bf12
--- /dev/null
+++ b/porting/liteos_a/user/src/exit/exit.c
@@ -0,0 +1,40 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <signal.h>
+#include <atomic.h>
+#include "libc.h"
+
+static void dummy()
+{
+}
+
+/* atexit.c and __stdio_exit.c override these. the latter is linked
+ * as a consequence of linking either __toread.c or __towrite.c. */
+weak_alias(dummy, __funcs_on_exit);
+weak_alias(dummy, __stdio_exit);
+weak_alias(dummy, _fini);
+
+extern weak hidden void (*const __fini_array_start)(void), (*const __fini_array_end)(void);
+
+static void libc_exit_fini(void)
+{
+	uintptr_t a = (uintptr_t)&__fini_array_end;
+	for (; a>(uintptr_t)&__fini_array_start; a-=sizeof(void(*)()))
+		(*(void (**)())(a-sizeof(void(*)())))();
+	_fini();
+}
+
+weak_alias(libc_exit_fini, __libc_exit_fini);
+
+_Noreturn void exit(int code)
+{
+	sigset_t set;
+	if (a_cas(&libc.exit, 0, 1) != 0) {
+		return;
+	}
+	__block_app_sigs(&set);
+	__funcs_on_exit();
+	__libc_exit_fini();
+	__stdio_exit();
+	_Exit(code);
+}
diff --git a/porting/liteos_a/user/src/internal/libc.h b/porting/liteos_a/user/src/internal/libc.h
index da237ed1..759f5b8a 100644
--- a/porting/liteos_a/user/src/internal/libc.h
+++ b/porting/liteos_a/user/src/internal/libc.h
@@ -27,6 +27,7 @@ struct __libc {
 	size_t tls_size, tls_align, tls_cnt;
 	size_t page_size;
 	struct __locale_struct global_locale;
+	int exit;
 };
 
 #ifndef PAGE_SIZE
diff --git a/porting/liteos_a/user/src/process/fork.c b/porting/liteos_a/user/src/process/fork.c
index b5b8dca0..160ef5d2 100644
--- a/porting/liteos_a/user/src/process/fork.c
+++ b/porting/liteos_a/user/src/process/fork.c
@@ -30,6 +30,7 @@ pid_t fork(void)
 		self->next = self->prev = self;
 		__thread_list_lock = 0;
 		libc.threads_minus_1 = 0;
+		libc.exit = 0;
 		signal(SIGSYS, arm_do_signal);
 	}
 	__restore_sigs(&set);
diff --git a/porting/liteos_a/user_debug/src/exit/exit.c b/porting/liteos_a/user_debug/src/exit/exit.c
index 5d2d00a3..945da520 100644
--- a/porting/liteos_a/user_debug/src/exit/exit.c
+++ b/porting/liteos_a/user_debug/src/exit/exit.c
@@ -2,6 +2,8 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <debug.h>
+#include <signal.h>
+#include <atomic.h>
 #include "libc.h"
 
 extern bool g_enable_check;
@@ -32,6 +34,11 @@ weak_alias(libc_exit_fini, __libc_exit_fini);
 
 _Noreturn void exit(int code)
 {
+	sigset_t set;
+	if (a_cas(&libc.exit, 0, 1) != 0) {
+		return;
+	}
+	__block_app_sigs(&set);
 	if (g_enable_check) {
 		check_leak();
 		check_heap_integrity();
-- 
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