From cf66c9bd08e69447f6fc8030d183f0c1c0dcba0e Mon Sep 17 00:00:00 2001
From: Roland McGrath <roland@redhat.com>
Date: Fri, 25 Jul 2008 19:45:51 -0700
Subject: [PATCH] --- yaml --- r: 106215 b: refs/heads/master c:
 35de254dc60f91004b3b5ebb1fc7b2c3093d6032 h: refs/heads/master i:   106213:
 723cada63f8d8ce8185fd628bbb5be49708a202f   106211:
 e579f675f7e7d02712b8f964d025a356c7c9f040   106207:
 a143731d63a8748c14efb36920437690f5ee3446 v: v3

---
 [refs]                          |  2 +-
 trunk/include/linux/tracehook.h | 19 +++++++++++++++++++
 trunk/kernel/signal.c           | 27 ++++++++++++++++-----------
 3 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/[refs] b/[refs]
index 6481e998409b..2fb252ca00c6 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c45aea27617d6a1e0aacddc3b0233f704222fcbd
+refs/heads/master: 35de254dc60f91004b3b5ebb1fc7b2c3093d6032
diff --git a/trunk/include/linux/tracehook.h b/trunk/include/linux/tracehook.h
index 2d1426f8e33b..8cffd34f88d5 100644
--- a/trunk/include/linux/tracehook.h
+++ b/trunk/include/linux/tracehook.h
@@ -312,4 +312,23 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info,
 		ptrace_notify(SIGTRAP);
 }
 
+/**
+ * tracehook_consider_ignored_signal - suppress short-circuit of ignored signal
+ * @task:		task receiving the signal
+ * @sig:		signal number being sent
+ * @handler:		%SIG_IGN or %SIG_DFL
+ *
+ * Return zero iff tracing doesn't care to examine this ignored signal,
+ * so it can short-circuit normal delivery and never even get queued.
+ * Either @handler is %SIG_DFL and @sig's default is ignore, or it's %SIG_IGN.
+ *
+ * Called with @task->sighand->siglock held.
+ */
+static inline int tracehook_consider_ignored_signal(struct task_struct *task,
+						    int sig,
+						    void __user *handler)
+{
+	return (task_ptrace(task) & PT_PTRACED) != 0;
+}
+
 #endif	/* <linux/tracehook.h> */
diff --git a/trunk/kernel/signal.c b/trunk/kernel/signal.c
index 8715c18b27b9..9efd1cee6d0b 100644
--- a/trunk/kernel/signal.c
+++ b/trunk/kernel/signal.c
@@ -22,6 +22,7 @@
 #include <linux/ptrace.h>
 #include <linux/signal.h>
 #include <linux/signalfd.h>
+#include <linux/tracehook.h>
 #include <linux/capability.h>
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
@@ -39,24 +40,21 @@
 
 static struct kmem_cache *sigqueue_cachep;
 
-static int __sig_ignored(struct task_struct *t, int sig)
+static void __user *sig_handler(struct task_struct *t, int sig)
 {
-	void __user *handler;
+	return t->sighand->action[sig - 1].sa.sa_handler;
+}
 
+static int sig_handler_ignored(void __user *handler, int sig)
+{
 	/* Is it explicitly or implicitly ignored? */
-
-	handler = t->sighand->action[sig - 1].sa.sa_handler;
 	return handler == SIG_IGN ||
 		(handler == SIG_DFL && sig_kernel_ignore(sig));
 }
 
 static int sig_ignored(struct task_struct *t, int sig)
 {
-	/*
-	 * Tracers always want to know about signals..
-	 */
-	if (t->ptrace & PT_PTRACED)
-		return 0;
+	void __user *handler;
 
 	/*
 	 * Blocked signals are never ignored, since the
@@ -66,7 +64,14 @@ static int sig_ignored(struct task_struct *t, int sig)
 	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
 		return 0;
 
-	return __sig_ignored(t, sig);
+	handler = sig_handler(t, sig);
+	if (!sig_handler_ignored(handler, sig))
+		return 0;
+
+	/*
+	 * Tracers may want to know about even ignored signals.
+	 */
+	return !tracehook_consider_ignored_signal(t, sig, handler);
 }
 
 /*
@@ -2298,7 +2303,7 @@ 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_ignored(t, sig)) {
+		if (sig_handler_ignored(sig_handler(t, sig), sig)) {
 			sigemptyset(&mask);
 			sigaddset(&mask, sig);
 			rm_from_queue_full(&mask, &t->signal->shared_pending);