[PATCH] livepatch: Replace the fake signal sending with TIF_NOTIFY_SIGNAL infrastructure

From: Miroslav Benes
Date: Fri Mar 26 2021 - 10:31:23 EST


Livepatch sends a fake signal to all remaining blocking tasks of a
running transition after a set period of time. It uses TIF_SIGPENDING
flag for the purpose. Commit 12db8b690010 ("entry: Add support for
TIF_NOTIFY_SIGNAL") added a generic infrastructure to achieve the same.
Replace our bespoke solution with the generic one.

Signed-off-by: Miroslav Benes <mbenes@xxxxxxx>
---
Tested on x86_64, s390x and ppc64le archs.

kernel/livepatch/transition.c | 5 ++---
kernel/signal.c | 3 +--
2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index f6310f848f34..3a4beb9395c4 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -9,6 +9,7 @@

#include <linux/cpu.h>
#include <linux/stacktrace.h>
+#include <linux/tracehook.h>
#include "core.h"
#include "patch.h"
#include "transition.h"
@@ -369,9 +370,7 @@ static void klp_send_signals(void)
* Send fake signal to all non-kthread tasks which are
* still not migrated.
*/
- spin_lock_irq(&task->sighand->siglock);
- signal_wake_up(task, 0);
- spin_unlock_irq(&task->sighand->siglock);
+ set_notify_signal(task);
}
}
read_unlock(&tasklist_lock);
diff --git a/kernel/signal.c b/kernel/signal.c
index f2a1b898da29..e52cb82aaecd 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -181,8 +181,7 @@ void recalc_sigpending_and_wake(struct task_struct *t)

void recalc_sigpending(void)
{
- if (!recalc_sigpending_tsk(current) && !freezing(current) &&
- !klp_patch_pending(current))
+ if (!recalc_sigpending_tsk(current) && !freezing(current))
clear_thread_flag(TIF_SIGPENDING);

}
--
2.30.2