path: root/kernel
diff options
authorOleg Nesterov <>2009-04-02 16:58:00 -0700
committerLinus Torvalds <>2009-04-02 19:04:58 -0700
commit43918f2bf4806675943416d539d9d5e4d585ebff (patch)
tree1de2ea08eed647b181b7f008f95e4bc4ec34c343 /kernel
parent90bc8d8b1a38f1ab131a2399a202e1889db95de8 (diff)
signals: remove 'handler' parameter to tracehook functions
Container-init must behave like global-init to processes within the container and hence it must be immune to unhandled fatal signals from within the container (i.e SIG_DFL signals that terminate the process). But the same container-init must behave like a normal process to processes in ancestor namespaces and so if it receives the same fatal signal from a process in ancestor namespace, the signal must be processed. Implementing these semantics requires that send_signal() determine pid namespace of the sender but since signals can originate from workqueues/ interrupt-handlers, determining pid namespace of sender may not always be possible or safe. This patchset implements the design/simplified semantics suggested by Oleg Nesterov. The simplified semantics for container-init are: - container-init must never be terminated by a signal from a descendant process. - container-init must never be immune to SIGKILL from an ancestor namespace (so a process in parent namespace must always be able to terminate a descendant container). - container-init may be immune to unhandled fatal signals (like SIGUSR1) even if they are from ancestor namespace. SIGKILL/SIGSTOP are the only reliable signals to a container-init from ancestor namespace. This patch: Based on an earlier patch submitted by Oleg Nesterov and comments from Roland McGrath ( The handler parameter is currently unused in the tracehook functions. Besides, the tracehook functions are called with siglock held, so the functions can check the handler if they later need to. Removing the parameter simiplifies changes to sig_ignored() in a follow-on patch. Signed-off-by: Sukadev Bhattiprolu <> Acked-by: Roland McGrath <> Signed-off-by: Oleg Nesterov <> Cc: "Eric W. Biederman" <> Cc: Daniel Lezcano <> Cc: Ingo Molnar <> Cc: Thomas Gleixner <> Cc: "H. Peter Anvin" <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'kernel')
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 1c8814481a11..92a1ab004498 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -74,7 +74,7 @@ static int sig_ignored(struct task_struct *t, int sig)
* Tracers may want to know about even ignored signals.
- return !tracehook_consider_ignored_signal(t, sig, handler);
+ return !tracehook_consider_ignored_signal(t, sig);
@@ -318,7 +318,7 @@ int unhandled_signal(struct task_struct *tsk, int sig)
return 1;
if (handler != SIG_IGN && handler != SIG_DFL)
return 0;
- return !tracehook_consider_fatal_signal(tsk, sig, handler);
+ return !tracehook_consider_fatal_signal(tsk, sig);
@@ -777,7 +777,7 @@ static void complete_signal(int sig, struct task_struct *p, int group)
!sigismember(&t->real_blocked, sig) &&
(sig == SIGKILL ||
- !tracehook_consider_fatal_signal(t, sig, SIG_DFL))) {
+ !tracehook_consider_fatal_signal(t, sig))) {
* This signal will be fatal to the whole group.