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Commit 9e8ae01d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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introduce "struct wait_opts" to simplify do_wait() patches 



Introduce "struct wait_opts" which holds the parameters for misc helpers
in do_wait() pathes.

This adds 13 lines to kernel/exit.c, but saves 256 bytes from .o and imho
makes the code much more readable.

This patch temporary uglifies rusage/siginfo code a little bit, will be
addressed by further cleanups.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 47918025

kernel/exit.c

+110 −97
Original line number Diff line number Diff line
@@ -1080,6 +1080,18 @@ SYSCALL_DEFINE1(exit_group, int, error_code) 
	return 0;

}



struct wait_opts {

	enum pid_type		wo_type;

	struct pid		*wo_pid;

	int			wo_flags;



	struct siginfo __user	*wo_info;

	int __user		*wo_stat;

	struct rusage __user	*wo_rusage;



	int			notask_error;

};



static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)

{

	struct pid *pid = NULL;
@@ -1090,13 +1102,12 @@ static struct pid *task_pid_type(struct task_struct *task, enum pid_type type) 
	return pid;

}



static int eligible_child(enum pid_type type, struct pid *pid, int options,

			  struct task_struct *p)

static int eligible_child(struct wait_opts *wo, struct task_struct *p)

{

	int err;



	if (type < PIDTYPE_MAX) {

		if (task_pid_type(p, type) != pid)

	if (wo->wo_type < PIDTYPE_MAX) {

		if (task_pid_type(p, wo->wo_type) != wo->wo_pid)

			return 0;

	}
@@ -1105,8 +1116,8 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options, 
	 * set; otherwise, wait for non-clone children *only*.  (Note:

	 * A "clone" child here is one that reports to its parent

	 * using a signal other than SIGCHLD.) */

	if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))

	    && !(options & __WALL))

	if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))

	    && !(wo->wo_flags & __WALL))

		return 0;



	err = security_task_wait(p);
@@ -1116,14 +1127,15 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options, 
	return 1;

}



static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,

			       int why, int status,

			       struct siginfo __user *infop,

			       struct rusage __user *rusagep)

static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,

				pid_t pid, uid_t uid, int why, int status)

{

	int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;

	struct siginfo __user *infop;

	int retval = wo->wo_rusage

		? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;



	put_task_struct(p);

	infop = wo->wo_info;

	if (!retval)

		retval = put_user(SIGCHLD, &infop->si_signo);

	if (!retval)
@@ -1147,19 +1159,18 @@ static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid, 
 * the lock and this task is uninteresting.  If we return nonzero, we have

 * released the lock and the system call should return.

 */

static int wait_task_zombie(struct task_struct *p, int options,

			    struct siginfo __user *infop,

			    int __user *stat_addr, struct rusage __user *ru)

static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)

{

	unsigned long state;

	int retval, status, traced;

	pid_t pid = task_pid_vnr(p);

	uid_t uid = __task_cred(p)->uid;

	struct siginfo __user *infop;



	if (!likely(options & WEXITED))

	if (!likely(wo->wo_flags & WEXITED))

		return 0;



	if (unlikely(options & WNOWAIT)) {

	if (unlikely(wo->wo_flags & WNOWAIT)) {

		int exit_code = p->exit_code;

		int why, status;
@@ -1172,8 +1183,7 @@ static int wait_task_zombie(struct task_struct *p, int options, 
			why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;

			status = exit_code & 0x7f;

		}

		return wait_noreap_copyout(p, pid, uid, why,

					   status, infop, ru);

		return wait_noreap_copyout(wo, p, pid, uid, why, status);

	}



	/*
@@ -1250,11 +1260,14 @@ static int wait_task_zombie(struct task_struct *p, int options, 
	 */

	read_unlock(&tasklist_lock);



	retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;

	retval = wo->wo_rusage

		? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;

	status = (p->signal->flags & SIGNAL_GROUP_EXIT)

		? p->signal->group_exit_code : p->exit_code;

	if (!retval && stat_addr)

		retval = put_user(status, stat_addr);

	if (!retval && wo->wo_stat)

		retval = put_user(status, wo->wo_stat);



	infop = wo->wo_info;

	if (!retval && infop)

		retval = put_user(SIGCHLD, &infop->si_signo);

	if (!retval && infop)
@@ -1322,10 +1335,10 @@ static int *task_stopped_code(struct task_struct *p, bool ptrace) 
 * the lock and this task is uninteresting.  If we return nonzero, we have

 * released the lock and the system call should return.

 */

static int wait_task_stopped(int ptrace, struct task_struct *p,

			     int options, struct siginfo __user *infop,

			     int __user *stat_addr, struct rusage __user *ru)

static int wait_task_stopped(struct wait_opts *wo,

				int ptrace, struct task_struct *p)

{

	struct siginfo __user *infop;

	int retval, exit_code, *p_code, why;

	uid_t uid = 0; /* unneeded, required by compiler */

	pid_t pid;
@@ -1333,7 +1346,7 @@ static int wait_task_stopped(int ptrace, struct task_struct *p, 
	/*

	 * Traditionally we see ptrace'd stopped tasks regardless of options.

	 */

	if (!ptrace && !(options & WUNTRACED))

	if (!ptrace && !(wo->wo_flags & WUNTRACED))

		return 0;



	exit_code = 0;
@@ -1347,7 +1360,7 @@ static int wait_task_stopped(int ptrace, struct task_struct *p, 
	if (!exit_code)

		goto unlock_sig;



	if (!unlikely(options & WNOWAIT))

	if (!unlikely(wo->wo_flags & WNOWAIT))

		*p_code = 0;



	/* don't need the RCU readlock here as we're holding a spinlock */
@@ -1369,14 +1382,15 @@ static int wait_task_stopped(int ptrace, struct task_struct *p, 
	why = ptrace ? CLD_TRAPPED : CLD_STOPPED;

	read_unlock(&tasklist_lock);



	if (unlikely(options & WNOWAIT))

		return wait_noreap_copyout(p, pid, uid,

					   why, exit_code,

					   infop, ru);

	if (unlikely(wo->wo_flags & WNOWAIT))

		return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);



	retval = wo->wo_rusage

		? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;

	if (!retval && wo->wo_stat)

		retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);



	retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;

	if (!retval && stat_addr)

		retval = put_user((exit_code << 8) | 0x7f, stat_addr);

	infop = wo->wo_info;

	if (!retval && infop)

		retval = put_user(SIGCHLD, &infop->si_signo);

	if (!retval && infop)
@@ -1403,15 +1417,13 @@ static int wait_task_stopped(int ptrace, struct task_struct *p, 
 * the lock and this task is uninteresting.  If we return nonzero, we have

 * released the lock and the system call should return.

 */

static int wait_task_continued(struct task_struct *p, int options,

			       struct siginfo __user *infop,

			       int __user *stat_addr, struct rusage __user *ru)

static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)

{

	int retval;

	pid_t pid;

	uid_t uid;



	if (!unlikely(options & WCONTINUED))

	if (!unlikely(wo->wo_flags & WCONTINUED))

		return 0;



	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
@@ -1423,7 +1435,7 @@ static int wait_task_continued(struct task_struct *p, int options, 
		spin_unlock_irq(&p->sighand->siglock);

		return 0;

	}

	if (!unlikely(options & WNOWAIT))

	if (!unlikely(wo->wo_flags & WNOWAIT))

		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;

	uid = __task_cred(p)->uid;

	spin_unlock_irq(&p->sighand->siglock);
@@ -1432,17 +1444,17 @@ static int wait_task_continued(struct task_struct *p, int options, 
	get_task_struct(p);

	read_unlock(&tasklist_lock);



	if (!infop) {

		retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;

	if (!wo->wo_info) {

		retval = wo->wo_rusage

			? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;

		put_task_struct(p);

		if (!retval && stat_addr)

			retval = put_user(0xffff, stat_addr);

		if (!retval && wo->wo_stat)

			retval = put_user(0xffff, wo->wo_stat);

		if (!retval)

			retval = pid;

	} else {

		retval = wait_noreap_copyout(p, pid, uid,

					     CLD_CONTINUED, SIGCONT,

					     infop, ru);

		retval = wait_noreap_copyout(wo, p, pid, uid,

					     CLD_CONTINUED, SIGCONT);

		BUG_ON(retval == 0);

	}
@@ -1452,19 +1464,16 @@ static int wait_task_continued(struct task_struct *p, int options, 
/*

 * Consider @p for a wait by @parent.

 *

 * -ECHILD should be in *@notask_error before the first call.

 * -ECHILD should be in ->notask_error before the first call.

 * Returns nonzero for a final return, when we have unlocked tasklist_lock.

 * Returns zero if the search for a child should continue;

 * then *@notask_error is 0 if @p is an eligible child,

 * then ->notask_error is 0 if @p is an eligible child,

 * or another error from security_task_wait(), or still -ECHILD.

 */

static int wait_consider_task(struct task_struct *parent, int ptrace,

			      struct task_struct *p, int *notask_error,

			      enum pid_type type, struct pid *pid, int options,

			      struct siginfo __user *infop,

			      int __user *stat_addr, struct rusage __user *ru)

static int wait_consider_task(struct wait_opts *wo, struct task_struct *parent,

				int ptrace, struct task_struct *p)

{

	int ret = eligible_child(type, pid, options, p);

	int ret = eligible_child(wo, p);

	if (!ret)

		return ret;
@@ -1476,8 +1485,8 @@ static int wait_consider_task(struct task_struct *parent, int ptrace, 
		 * to look for security policy problems, rather

		 * than for mysterious wait bugs.

		 */

		if (*notask_error)

			*notask_error = ret;

		if (wo->notask_error)

			wo->notask_error = ret;

		return 0;

	}
@@ -1486,7 +1495,7 @@ static int wait_consider_task(struct task_struct *parent, int ptrace, 
		 * This child is hidden by ptrace.

		 * We aren't allowed to see it now, but eventually we will.

		 */

		*notask_error = 0;

		wo->notask_error = 0;

		return 0;

	}
@@ -1497,34 +1506,30 @@ static int wait_consider_task(struct task_struct *parent, int ptrace, 
	 * We don't reap group leaders with subthreads.

	 */

	if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))

		return wait_task_zombie(p, options, infop, stat_addr, ru);

		return wait_task_zombie(wo, p);



	/*

	 * It's stopped or running now, so it might

	 * later continue, exit, or stop again.

	 */

	*notask_error = 0;

	wo->notask_error = 0;



	if (task_stopped_code(p, ptrace))

		return wait_task_stopped(ptrace, p, options,

					 infop, stat_addr, ru);

		return wait_task_stopped(wo, ptrace, p);



	return wait_task_continued(p, options, infop, stat_addr, ru);

	return wait_task_continued(wo, p);

}



/*

 * Do the work of do_wait() for one thread in the group, @tsk.

 *

 * -ECHILD should be in *@notask_error before the first call.

 * -ECHILD should be in ->notask_error before the first call.

 * Returns nonzero for a final return, when we have unlocked tasklist_lock.

 * Returns zero if the search for a child should continue; then

 * *@notask_error is 0 if there were any eligible children,

 * ->notask_error is 0 if there were any eligible children,

 * or another error from security_task_wait(), or still -ECHILD.

 */

static int do_wait_thread(struct task_struct *tsk, int *notask_error,

			  enum pid_type type, struct pid *pid, int options,

			  struct siginfo __user *infop, int __user *stat_addr,

			  struct rusage __user *ru)

static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)

{

	struct task_struct *p;
@@ -1533,9 +1538,7 @@ static int do_wait_thread(struct task_struct *tsk, int *notask_error, 
		 * Do not consider detached threads.

		 */

		if (!task_detached(p)) {

			int ret = wait_consider_task(tsk, 0, p, notask_error,

						     type, pid, options,

						     infop, stat_addr, ru);

			int ret = wait_consider_task(wo, tsk, 0, p);

			if (ret)

				return ret;

		}
@@ -1544,17 +1547,12 @@ static int do_wait_thread(struct task_struct *tsk, int *notask_error, 
	return 0;

}



static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,

			  enum pid_type type, struct pid *pid, int options,

			  struct siginfo __user *infop, int __user *stat_addr,

			  struct rusage __user *ru)

static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)

{

	struct task_struct *p;



	list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {

		int ret = wait_consider_task(tsk, 1, p, notask_error,

					     type, pid, options,

					     infop, stat_addr, ru);

		int ret = wait_consider_task(wo, tsk, 1, p);

		if (ret)

			return ret;

	}
@@ -1562,38 +1560,36 @@ static int ptrace_do_wait(struct task_struct *tsk, int *notask_error, 
	return 0;

}



static long do_wait(enum pid_type type, struct pid *pid, int options,

		    struct siginfo __user *infop, int __user *stat_addr,

		    struct rusage __user *ru)

static long do_wait(struct wait_opts *wo)

{

	DECLARE_WAITQUEUE(wait, current);

	struct task_struct *tsk;

	int retval;



	trace_sched_process_wait(pid);

	trace_sched_process_wait(wo->wo_pid);



	add_wait_queue(&current->signal->wait_chldexit,&wait);

repeat:

	/*

	 * If there is nothing that can match our critiera just get out.

	 * We will clear @retval to zero if we see any child that might later

	 * match our criteria, even if we are not able to reap it yet.

	 * We will clear ->notask_error to zero if we see any child that

	 * might later match our criteria, even if we are not able to reap

	 * it yet.

	 */

	retval = -ECHILD;

	if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))

	retval = wo->notask_error = -ECHILD;

	if ((wo->wo_type < PIDTYPE_MAX) &&

	   (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))

		goto end;



	current->state = TASK_INTERRUPTIBLE;

	read_lock(&tasklist_lock);

	tsk = current;

	do {

		int tsk_result = do_wait_thread(tsk, &retval,

						type, pid, options,

						infop, stat_addr, ru);

		int tsk_result = do_wait_thread(wo, tsk);



		if (!tsk_result)

			tsk_result = ptrace_do_wait(tsk, &retval,

						    type, pid, options,

						    infop, stat_addr, ru);

			tsk_result = ptrace_do_wait(wo, tsk);



		if (tsk_result) {

			/*

			 * tasklist_lock is unlocked and we have a final result.
@@ -1602,25 +1598,27 @@ static long do_wait(enum pid_type type, struct pid *pid, int options, 
			goto end;

		}



		if (options & __WNOTHREAD)

		if (wo->wo_flags & __WNOTHREAD)

			break;

		tsk = next_thread(tsk);

		BUG_ON(tsk->signal != current->signal);

	} while (tsk != current);

	read_unlock(&tasklist_lock);



	if (!retval && !(options & WNOHANG)) {

	retval = wo->notask_error;

	if (!retval && !(wo->wo_flags & WNOHANG)) {

		retval = -ERESTARTSYS;

		if (!signal_pending(current)) {

			schedule();

			goto repeat;

		}

	}



end:

	current->state = TASK_RUNNING;

	remove_wait_queue(&current->signal->wait_chldexit,&wait);

	if (infop) {

	if (wo->wo_info) {

		struct siginfo __user *infop = wo->wo_info;



		if (retval > 0)

			retval = 0;

		else {
@@ -1649,6 +1647,7 @@ static long do_wait(enum pid_type type, struct pid *pid, int options, 
SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,

		infop, int, options, struct rusage __user *, ru)

{

	struct wait_opts wo;

	struct pid *pid = NULL;

	enum pid_type type;

	long ret;
@@ -1678,7 +1677,14 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 


	if (type < PIDTYPE_MAX)

		pid = find_get_pid(upid);

	ret = do_wait(type, pid, options, infop, NULL, ru);



	wo.wo_type	= type;

	wo.wo_pid	= pid;

	wo.wo_flags	= options;

	wo.wo_info	= infop;

	wo.wo_stat	= NULL;

	wo.wo_rusage	= ru;

	ret = do_wait(&wo);

	put_pid(pid);



	/* avoid REGPARM breakage on x86: */
@@ -1689,6 +1695,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 
SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,

		int, options, struct rusage __user *, ru)

{

	struct wait_opts wo;

	struct pid *pid = NULL;

	enum pid_type type;

	long ret;
@@ -1710,7 +1717,13 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 
		pid = find_get_pid(upid);

	}



	ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);

	wo.wo_type	= type;

	wo.wo_pid	= pid;

	wo.wo_flags	= options | WEXITED;

	wo.wo_info	= NULL;

	wo.wo_stat	= stat_addr;

	wo.wo_rusage	= ru;

	ret = do_wait(&wo);

	put_pid(pid);



	/* avoid REGPARM breakage on x86: */