[PATCH 07/11] fork: Add kernel_clone_args flag to ignore signals

[Mike Christie]

Since:

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

kthreads have been ignoring signals by default, and the vhost layer has
never had a need to change that. This patch adds an option flag,
USER_WORKER_SIG_IGN, handled in copy_process() after copy_sighand()
and copy_signals() so vhost_tasks added in the next patches can continue
to ignore singals.

Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
 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 4f816048794f..00c54bfac0b5 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -29,6 +29,7 @@ struct kernel_clone_args {
 	u32 io_thread:1;
 	u32 user_worker:1;
 	u32 no_files:1;
+	u32 ignore_signals:1;
 	unsigned long stack;
 	unsigned long stack_size;
 	unsigned long tls;
diff --git a/kernel/fork.c b/kernel/fork.c
index 258163ea5cd2..244aae6c2395 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2287,6 +2287,9 @@ static __latent_entropy struct task_struct *copy_process(
 	if (retval)
 		goto bad_fork_cleanup_io;
 
+	if (args->ignore_signals)
+		ignore_signals(p);
+
 	stackleak_task_init(p);
 
 	if (pid != &init_struct_pid) {
-- 
2.25.1