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: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 110 insertions, 97 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index fd781b56401d..29622e468b7f 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -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 @@ unlock_sig:
         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 @@ unlock_sig:
  * 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 @@ repeat:
                         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 @@ end:
 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: */