signals: introduce do_send_sig_info() helper

Introduce do_send_sig_info() and convert group_send_sig_info(),
send_sig_info(), do_send_specific() to use this helper.

Hopefully it will have more users soon, it allows to specify
specific/group behaviour via "bool group" argument.

Shaves 80 bytes from .text.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: 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, 27 insertions, 29 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 5d3b3f8f219b..c6d7a24a86a1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -971,6 +971,20 @@ specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
         return send_signal(sig, info, t, 0);
 }
 
+int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
+                        bool group)
+{
+        unsigned long flags;
+        int ret = -ESRCH;
+
+        if (lock_task_sighand(p, &flags)) {
+                ret = send_signal(sig, info, p, group);
+                unlock_task_sighand(p, &flags);
+        }
+
+        return ret;
+}
+
 /*
  * Force a signal that the process can't ignore: if necessary
  * we unblock the signal and change any SIG_IGN to SIG_DFL.
@@ -1068,18 +1082,10 @@ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long
  */
 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
-        unsigned long flags;
-        int ret;
-
-        ret = check_kill_permission(sig, info, p);
+        int ret = check_kill_permission(sig, info, p);
 
-        if (!ret && sig) {
-                ret = -ESRCH;
-                if (lock_task_sighand(p, &flags)) {
-                        ret = __group_send_sig_info(sig, info, p);
-                        unlock_task_sighand(p, &flags);
-                }
-        }
+        if (!ret && sig)
+                ret = do_send_sig_info(sig, info, p, true);
 
         return ret;
 }
@@ -1224,15 +1230,9 @@ static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
  * These are for backward compatibility with the rest of the kernel source.
  */
 
-/*
- * The caller must ensure the task can't exit.
- */
 int
 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
-        int ret;
-        unsigned long flags;
-
         /*
          * Make sure legacy kernel users don't send in bad values
          * (normal paths check this in check_kill_permission).
@@ -1240,10 +1240,7 @@ send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
         if (!valid_signal(sig))
                 return -EINVAL;
 
-        spin_lock_irqsave(&p->sighand->siglock, flags);
-        ret = specific_send_sig_info(sig, info, p);
-        spin_unlock_irqrestore(&p->sighand->siglock, flags);
-        return ret;
+        return do_send_sig_info(sig, info, p, false);
 }
 
 #define __si_special(priv) \
@@ -2278,7 +2275,6 @@ static int
 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
 {
         struct task_struct *p;
-        unsigned long flags;
         int error = -ESRCH;
 
         rcu_read_lock();
@@ -2288,14 +2284,16 @@ do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
                 /*
                  * The null signal is a permissions and process existence
                  * probe.  No signal is actually delivered.
-                 *
-                 * If lock_task_sighand() fails we pretend the task dies
-                 * after receiving the signal. The window is tiny, and the
-                 * signal is private anyway.
                  */
-                if (!error && sig && lock_task_sighand(p, &flags)) {
-                        error = specific_send_sig_info(sig, info, p);
-                        unlock_task_sighand(p, &flags);
+                if (!error && sig) {
+                        error = do_send_sig_info(sig, info, p, false);
+                        /*
+                         * If lock_task_sighand() failed we pretend the task
+                         * dies after receiving the signal. The window is tiny,
+                         * and the signal is private anyway.
+                         */
+                        if (unlikely(error == -ESRCH))
+                                error = 0;
                 }
         }
         rcu_read_unlock();