allow_signal: kill the bogus ->mm check, add a note about CLONE_SIGHAND

[safe/jmp/linux-2.6] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index cab535c..533e5f8 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -48,6 +48,7 @@
 #include <linux/tracehook.h>
 #include <linux/fs_struct.h>
 #include <linux/init_task.h>
+#include <linux/perf_counter.h>
 #include <trace/events/sched.h>
 
 #include <asm/uaccess.h>
@@ -154,6 +155,9 @@ static void delayed_put_task_struct(struct rcu_head *rhp)
 {
        struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
 
+#ifdef CONFIG_PERF_COUNTERS
+       WARN_ON_ONCE(tsk->perf_counter_ctxp);
+#endif
        trace_sched_process_free(tsk);
        put_task_struct(tsk);
 }
@@ -170,6 +174,7 @@ repeat:
        atomic_dec(&__task_cred(p)->user->processes);
 
        proc_flush_task(p);
+
        write_lock_irq(&tasklist_lock);
        tracehook_finish_release_task(p);
        __exit_signal(p);
@@ -370,9 +375,8 @@ static void set_special_pids(struct pid *pid)
 }
 
 /*
- * Let kernel threads use this to say that they
- * allow a certain signal (since daemonize() will
- * have disabled all of them by default).
+ * Let kernel threads use this to say that they allow a certain signal.
+ * Must not be used if kthread was cloned with CLONE_SIGHAND.
  */
 int allow_signal(int sig)
 {
@@ -380,14 +384,14 @@ int allow_signal(int sig)
                return -EINVAL;
 
        spin_lock_irq(&current->sighand->siglock);
+       /* This is only needed for daemonize()'ed kthreads */
        sigdelset(&current->blocked, sig);
-       if (!current->mm) {
-               /* Kernel threads handle their own signals.
-                  Let the signal code know it'll be handled, so
-                  that they don't get converted to SIGKILL or
-                  just silently dropped */
-               current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
-       }
+       /*
+        * Kernel threads handle their own signals. Let the signal code
+        * know it'll be handled, so that they don't get converted to
+        * SIGKILL or just silently dropped.
+        */
+       current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);
        return 0;
@@ -971,16 +975,19 @@ NORET_TYPE void do_exit(long code)
                module_put(tsk->binfmt->module);
 
        proc_exit_connector(tsk);
+
+       /*
+        * Flush inherited counters to the parent - before the parent
+        * gets woken up by child-exit notifications.
+        */
+       perf_counter_exit_task(tsk);
+
        exit_notify(tsk, group_dead);
 #ifdef CONFIG_NUMA
        mpol_put(tsk->mempolicy);
        tsk->mempolicy = NULL;
 #endif
 #ifdef CONFIG_FUTEX
-       /*
-        * This must happen late, after the PID is not
-        * hashed anymore:
-        */
        if (unlikely(!list_empty(&tsk->pi_state_list)))
                exit_pi_state_list(tsk);
        if (unlikely(current->pi_state_cache))
@@ -1472,6 +1479,7 @@ static int wait_consider_task(struct task_struct *parent, int ptrace,
                 */
                if (*notask_error)
                        *notask_error = ret;
+               return 0;
        }
 
        if (likely(!ptrace) && unlikely(p->ptrace)) {