[Devel] [PATCH hci-8.1 v2 1/2] ms/um: Add os_set_pdeathsig helper function

[Eva Kurchatova]

From: Tiwei Bie <tiwei.btw at antgroup.com>

This helper can be used to set the parent-death signal of the calling
process to SIGKILL to ensure that the process will be killed if the
UML kernel dies unexpectedly without proper cleanup. This helper will
be used in the follow-up patches.

Signed-off-by: Tiwei Bie <tiwei.btw at antgroup.com>
Link: https://patch.msgid.link/20241024142828.2612828-2-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
(cherry picked from commit 4e5adbe447db382cc76e05613581f96aef4f91d2)

https://virtuozzo.atlassian.net/browse/VSTOR-143633
Feature: fix ms/um

Signed-off-by: Eva Kurchatova <eva.kurchatova at virtuozzo.com>
---
 arch/um/include/shared/os.h | 2 ++
 arch/um/os-Linux/process.c  | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 9a039d6f1f74..2ef3bb872b76 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -220,6 +220,8 @@ extern int os_drop_memory(void *addr, int length);
 extern int can_drop_memory(void);
 extern int os_mincore(void *addr, unsigned long len);
 
+void os_set_pdeathsig(void);
+
 /* execvp.c */
 extern int execvp_noalloc(char *buf, const char *file, char *const argv[]);
 /* helper.c */
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index e52dd37ddadc..d25d709488f2 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -12,6 +12,7 @@
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/ptrace.h>
+#include <sys/prctl.h>
 #include <sys/wait.h>
 #include <asm/unistd.h>
 #include <init.h>
@@ -285,3 +286,8 @@ void init_new_thread_signals(void)
 	set_handler(SIGIO);
 	signal(SIGWINCH, SIG_IGN);
 }
+
+void os_set_pdeathsig(void)
+{
+	prctl(PR_SET_PDEATHSIG, SIGKILL);
+}
-- 
2.56.0