进程回收过程注解

    百万汉字注解 + 百篇博客分析 => 挖透鸿蒙内核源码
    https://my.oschina.net/weharmony

arch/arm/arm/src/los_exc.c

@@ -540,7 +540,7 @@ STATIC VOID OsUserExcHandle(ExcContext *excBufAddr)
     UINT32 currCpu = ArchCurrCpuid();
     LosProcessCB *runProcess = OsCurrProcessGet();
 
-    if (g_excFromUserMode[ArchCurrCpuid()] == FALSE) {//内核态直接退出,8处理了.
+    if (g_excFromUserMode[ArchCurrCpuid()] == FALSE) {//内核态直接退出,不处理了.
         return;
     }
 
@@ -572,7 +572,7 @@ STATIC VOID OsUserExcHandle(ExcContext *excBufAddr)
 #endif
     OsProcessExitCodeSignalSet(runProcess, SIGUSR2);
     /* kill user exc process */
-    LOS_Exit(OS_PRO_EXIT_OK);
+    LOS_Exit(OS_PRO_EXIT_OK);//进程退出
 
     /* User mode exception handling failed , which normally does not exist */ //用户态的异常处理失败，通常情况下不会发生
     g_curNestCount[currCpu]++;

kernel/base/core/los_process.c

@@ -420,7 +420,7 @@ LITE_OS_SEC_TEXT STATIC VOID OsRecycleZombiesProcess(LosProcessCB *childCB, Proc
         OsInsertPCBToFreeList(childCB);//直接插到freeList中去，可用于重新分配了。
     }
 }
-//当一个进程自然退出的时候,它的孩子进程要怎么处理
+//当一个进程自然退出的时候,它的孩子进程由两位老祖宗收养
 STATIC VOID OsDealAliveChildProcess(LosProcessCB *processCB)
 {
     UINT32 parentID;
@@ -430,25 +430,25 @@ STATIC VOID OsDealAliveChildProcess(LosProcessCB *processCB)
     LOS_DL_LIST *childHead = NULL;
 
     if (!LOS_ListEmpty(&processCB->childrenList)) {//如果存在孩子进程
-        childHead = processCB->childrenList.pstNext;
-        LOS_ListDelete(&(processCB->childrenList));
+        childHead = processCB->childrenList.pstNext;//获取孩子链表
+        LOS_ListDelete(&(processCB->childrenList));//清空自己的孩子链表
         if (OsProcessIsUserMode(processCB)) {//是用户态进程
-            parentID = g_userInitProcess;//指定1号进程父ID
+            parentID = g_userInitProcess;//用户态进程老祖宗
         } else {
-            parentID = g_kernelInitProcess;//指定2号进程为父ID
+            parentID = g_kernelInitProcess;//内核态进程老祖宗
         }
 
-        for (nextList = childHead; ;) {
-            childCB = OS_PCB_FROM_SIBLIST(nextList);
-            childCB->parentProcessID = parentID;
-            nextList = nextList->pstNext;
-            if (nextList == childHead) {
+        for (nextList = childHead; ;) {//遍历孩子链表
+            childCB = OS_PCB_FROM_SIBLIST(nextList);//找到孩子的真身
+            childCB->parentProcessID = parentID;//孩子磕头认老祖宗为爸爸
+            nextList = nextList->pstNext;//找下一个孩子进程
+            if (nextList == childHead) {//一圈下来,孩子们都磕完头了
                 break;
             }
         }
 
-        parentCB = OS_PCB_FROM_PID(parentID);
-        LOS_ListTailInsertList(&parentCB->childrenList, childHead);
+        parentCB = OS_PCB_FROM_PID(parentID);//找个老祖宗的真身
+        LOS_ListTailInsertList(&parentCB->childrenList, childHead);//挂到老祖宗的孩子链表上
     }
 
     return;
@@ -1275,11 +1275,11 @@ STATIC UINT32 OsWaitOptionsCheck(UINT32 options)
     UINT32 flag = LOS_WAIT_WNOHANG | LOS_WAIT_WUNTRACED | LOS_WAIT_WCONTINUED;
 
     flag = ~flag & options;
-    if (flag != 0) {
+    if (flag != 0) {//三种方式中一种都没有
         return LOS_EINVAL;//无效参数
     }
 
-    if ((options & (LOS_WAIT_WCONTINUED | LOS_WAIT_WUNTRACED)) != 0) {
+    if ((options & (LOS_WAIT_WCONTINUED | LOS_WAIT_WUNTRACED)) != 0) {//暂不支持这两种方式.
         return LOS_EOPNOTSUPP;//不支持
     }
 
@@ -1299,7 +1299,7 @@ LITE_OS_SEC_TEXT INT32 LOS_Wait(INT32 pid, USER INT32 *status, UINT32 options, V
     LosProcessCB *processCB = NULL;
     LosTaskCB *runTask = NULL;
 
-    ret = OsWaitOptionsCheck(options);//参数检查 只支持 LOS_WAIT_WNOHANG | LOS_WAIT_WUNTRACED 
+    ret = OsWaitOptionsCheck(options);//参数检查,只支持LOS_WAIT_WNOHANG
     if (ret != LOS_OK) {
         return -ret;
     }
@@ -1318,7 +1318,7 @@ LITE_OS_SEC_TEXT INT32 LOS_Wait(INT32 pid, USER INT32 *status, UINT32 options, V
         return OsWaitRecycleChildPorcess(childCB, intSave, status);//回收进程
     }
 	//没有找到,看是否要返回还是去做个登记
-    if ((options & LOS_WAIT_WNOHANG) != 0) {//不登记的方式,立即返回
+    if ((options & LOS_WAIT_WNOHANG) != 0) {//有LOS_WAIT_WNOHANG标签
         runTask->waitFlag = 0;//等待标识置0
         pid = 0;//这里置0,是为了 return 0
         goto ERROR;

kernel/base/core/los_task.c

@@ -1140,7 +1140,7 @@ STATIC INLINE VOID OsTaskReleaseHoldLock(LosProcessCB *processCB, LosTaskCB *tas
 
     OsTaskSyncWake(taskCB);//同步唤醒任务
 }
-////删除一个正在运行的任务
+//删除一个正在运行的任务
 LITE_OS_SEC_TEXT VOID OsRunTaskToDelete(LosTaskCB *taskCB)
 {
     LosProcessCB *processCB = OS_PCB_FROM_PID(taskCB->processID);//拿到task所属进程

kernel/base/include/los_process_pri.h

@@ -338,18 +338,18 @@ STATIC INLINE BOOL OsProcessIsUserMode(const LosProcessCB *processCB)//用户模
  * 31    15           8           7        0
  * |     | exit code  | core dump | signal |
  */
-#define OS_PRO_EXIT_OK 0 //进程退出
-//以下函数都是进程的退出方式
+#define OS_PRO_EXIT_OK 0 //进程正常退出
+//置进程退出码第七位为1
 STATIC INLINE VOID OsProcessExitCodeCoreDumpSet(LosProcessCB *processCB)
 {
-    processCB->exitCode |= 0x80U;// 0b10000000 对应退出码为看
+    processCB->exitCode |= 0x80U;// 0b10000000 
 }
-
+//设置进程退出信号(0 ~ 7)
 STATIC INLINE VOID OsProcessExitCodeSignalSet(LosProcessCB *processCB, UINT32 signal)
 {
     processCB->exitCode |= signal & 0x7FU;//0b01111111
 }
-
+//清除进程退出信号(0 ~ 7)
 STATIC INLINE VOID OsProcessExitCodeSignalClear(LosProcessCB *processCB)
 {
     processCB->exitCode &= (~0x7FU);//低7位全部清0
@@ -359,8 +359,8 @@ STATIC INLINE BOOL OsProcessExitCodeSignalIsSet(LosProcessCB *processCB)
 {
     return (processCB->exitCode) & 0x7FU;
 }
-
-STATIC INLINE VOID OsProcessExitCodeSet(LosProcessCB *processCB, UINT32 code)//由外界提供退出码
+//设置进程退出号(8 ~ 15)
+STATIC INLINE VOID OsProcessExitCodeSet(LosProcessCB *processCB, UINT32 code)
 {
     processCB->exitCode |= ((code & 0x000000FFU) << 8U) & 0x0000FF00U; /* 8: Move 8 bits to the left, exitCode */
 }
@@ -426,14 +426,14 @@ STATIC INLINE User *OsCurrUserGet(VOID)//获取当前进程的所属用户
 /*
  * return immediately if no child has exited.
  */
-#define LOS_WAIT_WNOHANG   (1 << 0U) //如果没有孩子退出，请立即返回 no hang
+#define LOS_WAIT_WNOHANG   (1 << 0U) //如果没有孩子进程退出，则立即返回,而不是阻塞在这个函数上等待；如果结束了，则返回该子进程的进程号。
 
 /*
  * return if a child has stopped (but not traced via ptrace(2)).
  * Status for traced children which have stopped is provided even
  * if this option is not specified.
  */
-#define LOS_WAIT_WUNTRACED (1 << 1U) //如果子进程进入暂停执行情况则马上返回，但结束状态不予以理会。untraced
+#define LOS_WAIT_WUNTRACED (1 << 1U) //如果子进程进入暂停情况则马上返回，不予以理会结束状态。untraced
 
 /*
  * return if a stopped child has been resumed by delivery of SIGCONT.

kernel/base/ipc/los_signal.c

@@ -608,7 +608,7 @@ void OsSaveSignalContext(unsigned int *sp)
         /* One pthread do the share signal */ 
         sigcb->sigFlag |= process->sigShare;//记录由一个线程执行可进程的共享信号,这些恢复上下文时就找到对应的任务
         unsigned int signo = (unsigned int)FindFirstSetedBit(sigcb->sigFlag) + 1;
-        OsProcessExitCodeSignalSet(process, signo);
+        OsProcessExitCodeSignalSet(process, signo);//设置进程退出信号
         sigcb->context.CPSR = cpsr;		//保存当前各寄存器的信息
         sigcb->context.PC = sp[REG_PC]; //获取被打断现场寄存器的值
         sigcb->context.USP = sp[REG_SP];

syscall/process_syscall.c

@@ -308,7 +308,7 @@ int SysSchedRRGetInterval(int pid, struct timespec *tp)
 
     return 0;
 }
-//阻塞参数进程
+//等待子进程结束
 int SysWait(int pid, USER int *status, int options, void *rusage)
 {
     (void)rusage;