From: Steven Rostedt <[email protected]>
In order to know if a task is a user thread or a kernel thread it is
recommended to test the task flags for PF_KTHREAD. The old way was to
check if the task mm pointer is NULL.
It is an easy mistake to not test the flag correctly, as:
if (!(task->flag & PF_KTHREAD))
Is not immediately obvious that it's testing for a user thread.
Add helper functions:
is_user_thread()
is_kernel_thread()
that can make seeing what is being tested for much more obvious:
if (is_user_thread(task))
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Steven Rostedt (Google) <[email protected]>
---
include/linux/sched.h | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f96ac1982893..823f38b0fd3e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1785,6 +1785,16 @@ static __always_inline bool is_percpu_thread(void)
#endif
}
+static __always_inline bool is_user_thread(struct task_struct *task)
+{
+ return !(task->flags & PF_KTHREAD);
+}
+
+static __always_inline bool is_kernel_thread(struct task_struct *task)
+{
+ return task->flags & PF_KTHREAD;
+}
+
/* Per-process atomic flags. */
#define PFA_NO_NEW_PRIVS 0 /* May not gain new privileges.
*/
#define PFA_SPREAD_PAGE 1 /* Spread page cache
over cpuset */
--
2.47.2
