signals: cleanup the usage of t/current in do_sigaction()

The usage of "task_struct *t" and "current" in do_sigaction() looks really
annoying and chaotic.  Initially "t" is used as a cached value of current
but not consistently, then it is reused as a loop variable and we have to
use "current" again.

Clean up this mess and also convert the code to use for_each_thread().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 8 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index c088011f873c..a6d8c3af0ad6 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3068,16 +3068,16 @@ COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
 
 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
 {
-        struct task_struct *t = current;
+        struct task_struct *p = current, *t;
         struct k_sigaction *k;
         sigset_t mask;
 
         if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
                 return -EINVAL;
 
-        k = &t->sighand->action[sig-1];
+        k = &p->sighand->action[sig-1];
 
-        spin_lock_irq(&current->sighand->siglock);
+        spin_lock_irq(&p->sighand->siglock);
         if (oact)
                 *oact = *k;
 
@@ -3096,17 +3096,16 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
                  *   (for example, SIGCHLD), shall cause the pending signal to
                  *   be discarded, whether or not it is blocked"
                  */
-                if (sig_handler_ignored(sig_handler(t, sig), sig)) {
+                if (sig_handler_ignored(sig_handler(p, sig), sig)) {
                         sigemptyset(&mask);
                         sigaddset(&mask, sig);
-                        flush_sigqueue_mask(&mask, &t->signal->shared_pending);
-                        do {
+                        flush_sigqueue_mask(&mask, &p->signal->shared_pending);
+                        for_each_thread(p, t)
                                 flush_sigqueue_mask(&mask, &t->pending);
-                        } while_each_thread(current, t);
                 }
         }
 
-        spin_unlock_irq(&current->sighand->siglock);
+        spin_unlock_irq(&p->sighand->siglock);
         return 0;
 }