signal: remove warning about using SI_TKILL in rt_[tg]sigqueueinfo

Sending SI_TKILL from rt_[tg]sigqueueinfo was deprecated, so now we issue
a warning on the first attempt of doing it.  We use WARN_ON_ONCE, which is
not informative and, what is worse, taints the kernel, making the trinity
syscall fuzzer complain false-positively from time to time.

It does not look like we need this warning at all, because the behaviour
changed quite a long time ago (2.6.39), and if an application relies on
the old API, it gets EPERM anyway and can issue a warning by itself.

So let us zap the warning in kernel.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 9 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index a390499943e4..d51c5ddd855c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2992,11 +2992,9 @@ static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
          * Nor can they impersonate a kill()/tgkill(), which adds source info.
          */
         if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
-            (task_pid_vnr(current) != pid)) {
-                /* We used to allow any < 0 si_code */
-                WARN_ON_ONCE(info->si_code < 0);
+            (task_pid_vnr(current) != pid))
                 return -EPERM;
-        }
+
         info->si_signo = sig;
 
         /* POSIX.1b doesn't mention process groups.  */
@@ -3041,12 +3039,10 @@ static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
         /* Not even root can pretend to send signals from the kernel.
          * Nor can they impersonate a kill()/tgkill(), which adds source info.
          */
-        if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
-            (task_pid_vnr(current) != pid)) {
-                /* We used to allow any < 0 si_code */
-                WARN_ON_ONCE(info->si_code < 0);
+        if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
+            (task_pid_vnr(current) != pid))
                 return -EPERM;
-        }
+
         info->si_signo = sig;
 
         return do_send_specific(tgid, pid, sig, info);