[PATCH 9/9] samples/kretprobe: correctly check for kthreads

From: Mark Rutland
Date: Wed Aug 14 2019 - 06:42:08 EST


In general, a non-NULL current->mm doesn't imply that current is a
kthread, as kthreads can install an mm via use_mm(), and so it's
preferable to use is_kthread() to determine whether a thread is a
kthread.

For consistency, let's use is_kthread() here.

Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
samples/kprobes/kretprobe_example.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
index 186315ca88b3..d6e0bf196f0e 100644
--- a/samples/kprobes/kretprobe_example.c
+++ b/samples/kprobes/kretprobe_example.c
@@ -41,7 +41,7 @@ static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
struct my_data *data;

- if (!current->mm)
+ if (is_kthread(current))
return 1; /* Skip kernel threads */

data = (struct my_data *)ri->data;
--
2.11.0