4 files changed, 37 insertions, 5 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index e93691e9b325..c6d14b8008dd 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -24,6 +24,7 @@
 #include <linux/pid_namespace.h>
 #include <linux/ptrace.h>
 #include <linux/profile.h>
+#include <linux/signalfd.h>
 #include <linux/mount.h>
 #include <linux/proc_fs.h>
 #include <linux/kthread.h>
@@ -83,6 +84,14 @@ static void __exit_signal(struct task_struct *tsk)
         sighand = rcu_dereference(tsk->sighand);
         spin_lock(&sighand->siglock);
 
+        /*
+         * Notify that this sighand has been detached. This must
+         * be called with the tsk->sighand lock held. Also, this
+         * access tsk->sighand internally, so it must be called
+         * before tsk->sighand is reset.
+         */
+        signalfd_detach_locked(tsk);
+
         posix_cpu_timers_exit(tsk);
         if (atomic_dec_and_test(&sig->count))
                 posix_cpu_timers_exit_group(tsk);
diff --git a/kernel/fork.c b/kernel/fork.c
index 083bf8953ce8..49530e40ea8b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1422,12 +1422,15 @@ long do_fork(unsigned long clone_flags,
 #define ARCH_MIN_MMSTRUCT_ALIGN 0
 #endif
 
-static void sighand_ctor(void *data, struct kmem_cache *cachep, unsigned long flags)
+static void sighand_ctor(void *data, struct kmem_cache *cachep,
+                        unsigned long flags)
 {
         struct sighand_struct *sighand = data;
 
-        if (flags & SLAB_CTOR_CONSTRUCTOR)
+        if (flags & SLAB_CTOR_CONSTRUCTOR) {
                 spin_lock_init(&sighand->siglock);
+                INIT_LIST_HEAD(&sighand->signalfd_list);
+        }
 }
 
 void __init proc_caches_init(void)
@@ -1453,7 +1456,6 @@ void __init proc_caches_init(void)
                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
 }
 
-
 /*
  * Check constraints on flags passed to the unshare system call and
  * force unsharing of additional process context as appropriate.
diff --git a/kernel/signal.c b/kernel/signal.c
index 2ac3a668d9dd..34b7d6abce8f 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -21,6 +21,7 @@
 #include <linux/syscalls.h>
 #include <linux/ptrace.h>
 #include <linux/signal.h>
+#include <linux/signalfd.h>
 #include <linux/capability.h>
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
@@ -113,8 +114,7 @@ void recalc_sigpending(void)
 
 /* Given the mask, find the first available signal that should be serviced. */
 
-static int
-next_signal(struct sigpending *pending, sigset_t *mask)
+int next_signal(struct sigpending *pending, sigset_t *mask)
 {
         unsigned long i, *s, *m, x;
         int sig = 0;
@@ -630,6 +630,12 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
         int ret = 0;
 
         /*
+         * Deliver the signal to listening signalfds. This must be called
+         * with the sighand lock held.
+         */
+        signalfd_notify(t, sig);
+
+        /*
          * fast-pathed signals for kernel-internal things like SIGSTOP
          * or SIGKILL.
          */
@@ -1280,6 +1286,11 @@ int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
                 ret = 1;
                 goto out;
         }
+        /*
+         * Deliver the signal to listening signalfds. This must be called
+         * with the sighand lock held.
+         */
+        signalfd_notify(p, sig);
 
         list_add_tail(&q->list, &p->pending.list);
         sigaddset(&p->pending.signal, sig);
@@ -1323,6 +1334,11 @@ send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
                 q->info.si_overrun++;
                 goto out;
         } 
+        /*
+         * Deliver the signal to listening signalfds. This must be called
+         * with the sighand lock held.
+         */
+        signalfd_notify(p, sig);
 
         /*
          * Put this signal on the shared-pending queue.
@@ -1983,6 +1999,8 @@ int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
         /*
          * If you change siginfo_t structure, please be sure
          * this code is fixed accordingly.
+         * Please remember to update the signalfd_copyinfo() function
+         * inside fs/signalfd.c too, in case siginfo_t changes.
          * It should never copy any pad contained in the structure
          * to avoid security leaks, but must copy the generic
          * 3 ints plus the relevant union member.
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index d7306d0f3dfc..807e9bb8fcdb 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -141,3 +141,6 @@ cond_syscall(compat_sys_migrate_pages);
 cond_syscall(sys_bdflush);
 cond_syscall(sys_ioprio_set);
 cond_syscall(sys_ioprio_get);
+
+/* New file descriptors */
+cond_syscall(sys_signalfd);