signal: introduce do_sigtimedwait() to factor out compat/native code

Factor out the common code in sys_rt_sigtimedwait/compat_sys_rt_sigtimedwait
to the new helper, do_sigtimedwait().

Add the comment to document the extra tick we add to timespec_to_jiffies(ts),
thanks to Linus who explained this to me.

Perhaps it would be better to move compat_sys_rt_sigtimedwait() into
signal.c under CONFIG_COMPAT, then we can make do_sigtimedwait() static.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Matt Fleming <matt.fleming@linux.intel.com>

1 files changed, 7 insertions, 34 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index 06cbb0619531..9214dcd087b7 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -890,10 +890,9 @@ compat_sys_rt_sigtimedwait (compat_sigset_t __user *uthese,
 {
         compat_sigset_t s32;
         sigset_t s;
-        int sig;
         struct timespec t;
         siginfo_t info;
-        long ret, timeout;
+        long ret;
 
         if (sigsetsize != sizeof(sigset_t))
                 return -EINVAL;
@@ -901,45 +900,19 @@ compat_sys_rt_sigtimedwait (compat_sigset_t __user *uthese,
         if (copy_from_user(&s32, uthese, sizeof(compat_sigset_t)))
                 return -EFAULT;
         sigset_from_compat(&s, &s32);
-        sigdelsetmask(&s,sigmask(SIGKILL)|sigmask(SIGSTOP));
-        signotset(&s);
 
-        timeout = MAX_SCHEDULE_TIMEOUT;
         if (uts) {
-                if (get_compat_timespec (&t, uts))
+                if (get_compat_timespec(&t, uts))
                         return -EFAULT;
-                if (!timespec_valid(&t))
-                        return -EINVAL;
-                timeout = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
         }
 
-        spin_lock_irq(&current->sighand->siglock);
-        sig = dequeue_signal(current, &s, &info);
-        if (!sig && timeout) {
-                current->real_blocked = current->blocked;
-                sigandsets(&current->blocked, &current->blocked, &s);
-                recalc_sigpending();
-                spin_unlock_irq(&current->sighand->siglock);
-
-                timeout = schedule_timeout_interruptible(timeout);
-
-                spin_lock_irq(&current->sighand->siglock);
-                sig = dequeue_signal(current, &s, &info);
-                current->blocked = current->real_blocked;
-                siginitset(&current->real_blocked, 0);
-                recalc_sigpending();
-        }
-        spin_unlock_irq(&current->sighand->siglock);
+        ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
 
-        if (sig) {
-                ret = sig;
-                if (uinfo) {
-                        if (copy_siginfo_to_user32(uinfo, &info))
-                                ret = -EFAULT;
-                }
-        } else {
-                ret = timeout?-EINTR:-EAGAIN;
+        if (ret > 0 && uinfo) {
+                if (copy_siginfo_to_user32(uinfo, &info))
+                        ret = -EFAULT;
         }
+
         return ret;
 
 }