[PATCH V4 4/8] fork: Add KERNEL_WORKER flag to ignore signals

[Mike Christie <michael.christie@oracle.com>]

From: Christian Brauner <christian.brauner@ubuntu.com>

Since this is mirroring kthread's sig ignore api introduced in

commit 10ab825bdef8 ("change kernel threads to ignore signals instead of
blocking them")

this patch adds an option flag, KERNEL_WORKER_SIG_IGN, handled in
copy_process() after copy_sighand() and copy_signals() to ease the
transition from kthreads to this new api.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 include/linux/sched/task.h | 1 +
 kernel/fork.c              | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 1153f9e5d10e..5f3928fe0544 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -21,6 +21,7 @@ struct css_set;
 #define KERN_WORKER_IO		BIT(0)
 #define KERN_WORKER_USER	BIT(1)
 #define KERN_WORKER_NO_FILES	BIT(2)
+#define KERN_WORKER_SIG_IGN	BIT(3)
 
 struct kernel_clone_args {
 	u64 flags;
diff --git a/kernel/fork.c b/kernel/fork.c
index 3161edac1236..07f9e410fb64 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2213,6 +2213,9 @@ static __latent_entropy struct task_struct *copy_process(
 	if (retval)
 		goto bad_fork_cleanup_io;
 
+	if (args->worker_flags & KERN_WORKER_SIG_IGN)
+		ignore_signals(p);
+
 	stackleak_task_init(p);
 
 	if (pid != &init_struct_pid) {
-- 
2.25.1