int do_exit(long code)
{
int i;
free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));
free_page_tables(get_base(current->ldt[2]),get_limit(0x17));
for (i=0 ; i<NR_TASKS ; i++)
if (task[i] && task[i]->father == current->pid) {
task[i]->father = 1;
if (task[i]->state == TASK_ZOMBIE)
/* assumption task[1] is always init */
(void) send_sig(SIGCHLD, task[1], 1);
}
for (i=0 ; i<NR_OPEN ; i++)
if (current->filp[i])
sys_close(i);
iput(current->pwd);
current->pwd=NULL;
iput(current->root);
current->root=NULL;
iput(current->executable);
current->executable=NULL;
if (current->leader && current->tty >= 0)
tty_table[current->tty].pgrp = 0;
if (last_task_used_math == current)
last_task_used_math = NULL;
if (current->leader)
kill_session();
current->state = TASK_ZOMBIE;
current->exit_code = code;
tell_father(current->father);
schedule();
return (-1); /* just to suppress warnings */
}
int do_exit(long code)
{
int i;
free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));
free_page_tables(get_base(current->ldt[2]),get_limit(0x17));
for (i=0 ; i<NR_TASKS ; i++)
if (task[i] && task[i]->father == current->pid)
task[i]->father = 0;
for (i=0 ; i<NR_OPEN ; i++)
if (current->filp[i])
sys_close(i);
iput(current->pwd);
current->pwd=NULL;
iput(current->root);
current->root=NULL;
if (current->leader && current->tty >= 0)
tty_table[current->tty].pgrp = 0;
if (last_task_used_math == current)
last_task_used_math = NULL;
if (current->father) {
current->state = TASK_ZOMBIE;
do_kill(current->father,SIGCHLD,1);
current->exit_code = code;
} else
release(current);
schedule();
return (-1); /* just to suppress warnings */
}
int do_exit(long code)
{
int i;
// TODO 待看页表
free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));
free_page_tables(get_base(current->ldt[2]),get_limit(0x17));
/*
* 找出所有子进程，将它们的父亲设为 init 进程，将状态标记为僵尸
* 然后给 init 进程发送一个 SIGCHLD 信号，提醒 init 进程回收子进程
*/
for (i=0 ; i<NR_TASKS ; i++)
if (task[i] && task[i]->father == current->pid) {
task[i]->father = 1;
if (task[i]->state == TASK_ZOMBIE)
/* assumption task[1] is always init */
// 最后一个参数 1 代表 privilege，此处为强制发送
(void) send_sig(SIGCHLD, task[1], 1);
}
// TODO 关闭文件？
/*
* NR_OPEN 是一个进程可以打开的最大文件数
* 而 NR_FILE 是系统在某时刻的限制文件总数
*/
for (i=0 ; i<NR_OPEN ; i++)
if (current->filp[i])
sys_close(i);
// 进程的当前工作目录 inode
iput(current->pwd);
current->pwd=NULL;
// 进程的根目录 inode
iput(current->root);
current->root=NULL;
// 进程本身可执行文件的 inode
iput(current->executable);
current->executable=NULL;
if (current->leader && current->tty >= 0)
tty_table[current->tty].pgrp = 0;
if (last_task_used_math == current)
last_task_used_math = NULL;
/*
* 如果是 session leader 会话领头进程，则向该会话所有进程发送 SIGHUP 信号
* PID, PPID, PGID, SID
* http://unix.stackexchange.com/questions/18166/what-are-session-leaders-in-ps
* 在同一次 ssh 会话中，用户对应的 shell 最先被启动，成为 session leader，
* 所有在同一次会话中产生的进程 session id 都等于这个 session leader 的 pid
* 当 session leader 退出时，它会向所有同一 session 中的进程发送 SIGHUP，
* 这个信号是可以被捕获的，如果进程忽略这个 SIGHUP，它则可以以一个孤儿进程继续执行
* http://www.firefoxbug.com/index.php/archives/2782/
*/
if (current->leader)
kill_session();
// 将自己设为僵尸，设置退出状态码，同时告诉父进程回收子进程
current->state = TASK_ZOMBIE;
current->exit_code = code;
tell_father(current->father);
// 如果 tell_father 中找不到父进程，自己把自己释放掉了，那也不会有机会继续执行下面代码了
schedule();
return (-1); /* just to suppress warnings */
}
//// 程序退出处理程序。在系统调用的中断处理程序中被调用。
int
do_exit (long code) // code 是错误码。
{
int i;
// 释放当前进程代码段和数据段所占的内存页(free_page_tables()在mm/memory.c,105 行)。
free_page_tables (get_base (current->ldt[1]), get_limit (0x0f));
free_page_tables (get_base (current->ldt[2]), get_limit (0x17));
// 如果当前进程有子进程，就将子进程的father 置为1(其父进程改为进程1)。如果该子进程已经
// 处于僵死(ZOMBIE)状态，则向进程1 发送子进程终止信号SIGCHLD。
for (i = 0; i < NR_TASKS; i++)
if (task[i] && task[i]->father == current->pid)
{
task[i]->father = 1;
if (task[i]->state == TASK_ZOMBIE)
/* assumption task[1] is always init */
(void) send_sig (SIGCHLD, task[1], 1);
}
// 关闭当前进程打开着的所有文件。
for (i = 0; i < NR_OPEN; i++)
if (current->filp[i])
sys_close (i);
// 对当前进程工作目录pwd、根目录root 以及运行程序的i 节点进行同步操作，并分别置空。
iput (current->pwd);
current->pwd = NULL;
iput (current->root);
current->root = NULL;
iput (current->executable);
current->executable = NULL;
// 如果当前进程是领头(leader)进程并且其有控制的终端，则释放该终端。
if (current->leader && current->tty >= 0)
tty_table[current->tty].pgrp = 0;
// 如果当前进程上次使用过协处理器，则将last_task_used_math 置空。
if (last_task_used_math == current)
last_task_used_math = NULL;
// 如果当前进程是leader 进程，则终止所有相关进程。
if (current->leader)
kill_session ();
// 把当前进程置为僵死状态，并设置退出码。
current->state = TASK_ZOMBIE;
current->exit_code = code;
// 通知父进程，也即向父进程发送信号SIGCHLD -- 子进程将停止或终止。
tell_father (current->father);
schedule (); // 重新调度进程的运行。
return (-1); /* just to suppress warnings */
}
int sys_shmdt(void *shmaddr)
{
unsigned long data_base, vir_addr;
data_base = get_base(current->ldt[2]);
vir_addr = data_base + current->brk - PAGE_SIZE;
if(((unsigned long)shmaddr<=vir_addr) && ((unsigned long)shmaddr>data_base)){
free_page_tables((unsigned long)shmaddr, PAGE_SIZE);
current->brk -= PAGE_SIZE;
return 0;
}
return -EINVAL;
}
static inline void __exit_mm(struct task_struct * tsk)
{
struct mm_struct * mm = tsk->mm;
/* Set us up to use the kernel mm state */
if (mm != &init_mm) {
flush_cache_mm(mm);
flush_tlb_mm(mm);
tsk->mm = &init_mm;
tsk->swappable = 0;
SET_PAGE_DIR(tsk, swapper_pg_dir);
/* free the old state - not used any more */
if (!--mm->count) {
exit_mmap(mm);
free_page_tables(mm);
kfree(mm);
}
}
}
// 设置新任务的代码和数据段基址、限长并复制页表。
// nr 为新任务号；p 是新任务数据结构的指针。
int copy_mem (int nr, struct task_struct *p)
{
unsigned long old_data_base, new_data_base, data_limit;
unsigned long old_code_base, new_code_base, code_limit;
code_limit = get_limit (0x0f); // 取局部描述符表中代码段描述符项中段限长。
data_limit = get_limit (0x17); // 取局部描述符表中数据段描述符项中段限长。
old_code_base = get_base (current->ldt[1]); // 取原代码段基址。
old_data_base = get_base (current->ldt[2]); // 取原数据段基址。
if (old_data_base != old_code_base) // 0.11 版不支持代码和数据段分立的情况。
panic ("We don't support separate I&D");
if (data_limit < code_limit) // 如果数据段长度 < 代码段长度也不对。
panic ("Bad data_limit");
new_data_base = new_code_base = nr * 0x4000000; // 新基址=任务号*64Mb(任务大小)。
p->start_code = new_code_base;
set_base (p->ldt[1], new_code_base); // 设置代码段描述符中基址域。
set_base (p->ldt[2], new_data_base); // 设置数据段描述符中基址域。
if (copy_page_tables (old_data_base, new_data_base, data_limit))
{ // 复制代码和数据段。
free_page_tables (new_data_base, data_limit); // 如果出错则释放申请的内存。
return -ENOMEM;
}
return 0;
}
volatile void do_exit(long code)
{
struct task_struct *p;
int i;
fake_volatile:
free_page_tables(current);
for (i=0 ; i<NR_OPEN ; i++)
if (current->filp[i])
sys_close(i);
forget_original_parent(current);
iput(current->pwd);
current->pwd = NULL;
iput(current->root);
current->root = NULL;
iput(current->executable);
current->executable = NULL;
for (i=0; i < current->numlibraries; i++) {
iput(current->libraries[i].library);
current->libraries[i].library = NULL;
}
current->state = TASK_ZOMBIE;
current->exit_code = code;
current->rss = 0;
/*
* Check to see if any process groups have become orphaned
* as a result of our exiting, and if they have any stopped
* jobs, send them a SIGUP and then a SIGCONT. (POSIX 3.2.2.2)
*
* Case i: Our father is in a different pgrp than we are
* and we were the only connection outside, so our pgrp
* is about to become orphaned.
*/
if ((current->p_pptr->pgrp != current->pgrp) &&
(current->p_pptr->session == current->session) &&
is_orphaned_pgrp(current->pgrp) &&
has_stopped_jobs(current->pgrp)) {
kill_pg(current->pgrp,SIGHUP,1);
kill_pg(current->pgrp,SIGCONT,1);
}
/* Let father know we died */
send_sig (SIGCHLD, current->p_pptr, 1);
/*
* This loop does two things:
*
* A. Make init inherit all the child processes
* B. Check to see if any process groups have become orphaned
* as a result of our exiting, and if they have any stopped
* jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
*/
while ((p = current->p_cptr) != NULL) {
current->p_cptr = p->p_osptr;
p->p_ysptr = NULL;
p->flags &= ~(PF_PTRACED|PF_TRACESYS);
if (task[1])
p->p_pptr = task[1];
else
p->p_pptr = task[0];
p->p_osptr = p->p_pptr->p_cptr;
p->p_osptr->p_ysptr = p;
p->p_pptr->p_cptr = p;
if (p->state == TASK_ZOMBIE)
send_sig(SIGCHLD,p->p_pptr,1);
/*
* process group orphan check
* Case ii: Our child is in a different pgrp
* than we are, and it was the only connection
* outside, so the child pgrp is now orphaned.
*/
if ((p->pgrp != current->pgrp) &&
(p->session == current->session) &&
is_orphaned_pgrp(p->pgrp) &&
has_stopped_jobs(p->pgrp)) {
kill_pg(p->pgrp,SIGHUP,1);
kill_pg(p->pgrp,SIGCONT,1);
}
}
if (current->leader) {
struct task_struct **p;
struct tty_struct *tty;
if (current->tty >= 0) {
tty = TTY_TABLE(current->tty);
if (tty) {
if (tty->pgrp > 0)
kill_pg(tty->pgrp, SIGHUP, 1);
tty->pgrp = -1;
tty->session = 0;
}
}
for (p = &LAST_TASK ; p > &FIRST_TASK ; --p)
if (*p && (*p)->session == current->session)
(*p)->tty = -1;
}
if (last_task_used_math == current)
last_task_used_math = NULL;
#ifdef DEBUG_PROC_TREE
audit_ptree();
#endif
schedule();
/*
* In order to get rid of the "volatile function does return" message
* I did this little loop that confuses gcc to think do_exit really
* is volatile. In fact it's schedule() that is volatile in some
* circumstances: when current->state = ZOMBIE, schedule() never
* returns.
*
* In fact the natural way to do all this is to have the label and the
* goto right after each other, but I put the fake_volatile label at
* the start of the function just in case something /really/ bad
* happens, and the schedule returns. This way we can try again. I'm
* not paranoid: it's just that everybody is out to get me.
*/
goto fake_volatile;
}
NORET_TYPE void do_exit(long code)
{
struct task_struct *p;
int i;
fake_volatile:
if (current->semun)
sem_exit();
if (current->shm)
shm_exit();
free_page_tables(current);
for (i=0 ; i<NR_OPEN ; i++)
if (current->filp[i])
sys_close(i);
forget_original_parent(current);
iput(current->pwd);
current->pwd = NULL;
iput(current->root);
current->root = NULL;
iput(current->executable);
current->executable = NULL;
/* Release all of the old mmap stuff. */
{
struct vm_area_struct * mpnt, *mpnt1;
mpnt = current->mmap;
current->mmap = NULL;
while (mpnt) {
mpnt1 = mpnt->vm_next;
if (mpnt->vm_ops && mpnt->vm_ops->close)
mpnt->vm_ops->close(mpnt);
kfree(mpnt);
mpnt = mpnt1;
}
}
if (current->ldt) {
vfree(current->ldt);
current->ldt = NULL;
for (i=1 ; i<NR_TASKS ; i++) {
if (task[i] == current) {
set_ldt_desc(gdt+(i<<1)+FIRST_LDT_ENTRY, &default_ldt, 1);
load_ldt(i);
}
}
}
current->state = TASK_ZOMBIE;
current->exit_code = code;
current->rss = 0;
/*
* Check to see if any process groups have become orphaned
* as a result of our exiting, and if they have any stopped
* jobs, send them a SIGUP and then a SIGCONT. (POSIX 3.2.2.2)
*
* Case i: Our father is in a different pgrp than we are
* and we were the only connection outside, so our pgrp
* is about to become orphaned.
*/
if ((current->p_pptr->pgrp != current->pgrp) &&
(current->p_pptr->session == current->session) &&
is_orphaned_pgrp(current->pgrp) &&
has_stopped_jobs(current->pgrp)) {
kill_pg(current->pgrp,SIGHUP,1);
kill_pg(current->pgrp,SIGCONT,1);
}
/* Let father know we died */
/* 通知父进程 */
notify_parent(current);
/*
* This loop does two things:
*
* A. Make init inherit all the child processes
* B. Check to see if any process groups have become orphaned
* as a result of our exiting, and if they have any stopped
* jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
*/
while ((p = current->p_cptr) != NULL) {
current->p_cptr = p->p_osptr;
p->p_ysptr = NULL;
p->flags &= ~(PF_PTRACED|PF_TRACESYS);
if (task[1] && task[1] != current)
p->p_pptr = task[1];
else
p->p_pptr = task[0];
p->p_osptr = p->p_pptr->p_cptr;
p->p_osptr->p_ysptr = p;
p->p_pptr->p_cptr = p;
if (p->state == TASK_ZOMBIE)
notify_parent(p);
/*
* process group orphan check
* Case ii: Our child is in a different pgrp
* than we are, and it was the only connection
* outside, so the child pgrp is now orphaned.
*/
if ((p->pgrp != current->pgrp) &&
(p->session == current->session) &&
is_orphaned_pgrp(p->pgrp) &&
has_stopped_jobs(p->pgrp)) {
kill_pg(p->pgrp,SIGHUP,1);
kill_pg(p->pgrp,SIGCONT,1);
}
}
if (current->leader)
disassociate_ctty(1);
if (last_task_used_math == current)
last_task_used_math = NULL;
#ifdef DEBUG_PROC_TREE
audit_ptree();
#endif
schedule();
/*
* In order to get rid of the "volatile function does return" message
* I did this little loop that confuses gcc to think do_exit really
* is volatile. In fact it's schedule() that is volatile in some
* circumstances: when current->state = ZOMBIE, schedule() never
* returns.
*
* In fact the natural way to do all this is to have the label and the
* goto right after each other, but I put the fake_volatile label at
* the start of the function just in case something /really/ bad
* happens, and the schedule returns. This way we can try again. I'm
* not paranoid: it's just that everybody is out to get me.
*/
goto fake_volatile;
}
