Unverified Commit 74198dc2 authored by Mateusz Guzik's avatar Mateusz Guzik Committed by Christian Brauner
Browse files

pid: sprinkle tasklist_lock asserts 



They cost nothing on production kernels and document the requirement of
holding the tasklist_lock lock in respective routines.

Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarMateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250206164415.450051-4-mjguzik@gmail.com


Acked-by: default avatar"Liam R. Howlett" <Liam.Howlett@Oracle.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 6731cd97

kernel/pid.c

+12 −3
Original line number Diff line number Diff line
@@ -339,17 +339,23 @@ static struct pid **task_pid_ptr(struct task_struct *task, enum pid_type type) 
 */

void attach_pid(struct task_struct *task, enum pid_type type)

{

	struct pid *pid = *task_pid_ptr(task, type);

	struct pid *pid;



	lockdep_assert_held_write(&tasklist_lock);



	pid = *task_pid_ptr(task, type);

	hlist_add_head_rcu(&task->pid_links[type], &pid->tasks[type]);

}



static void __change_pid(struct task_struct *task, enum pid_type type,

			struct pid *new)

{

	struct pid **pid_ptr = task_pid_ptr(task, type);

	struct pid *pid;

	struct pid **pid_ptr, *pid;

	int tmp;



	lockdep_assert_held_write(&tasklist_lock);



	pid_ptr = task_pid_ptr(task, type);

	pid = *pid_ptr;



	hlist_del_rcu(&task->pid_links[type]);
@@ -386,6 +392,8 @@ void exchange_tids(struct task_struct *left, struct task_struct *right) 
	struct hlist_head *head1 = &pid1->tasks[PIDTYPE_PID];

	struct hlist_head *head2 = &pid2->tasks[PIDTYPE_PID];



	lockdep_assert_held_write(&tasklist_lock);



	/* Swap the single entry tid lists */

	hlists_swap_heads_rcu(head1, head2);
@@ -403,6 +411,7 @@ void transfer_pid(struct task_struct *old, struct task_struct *new, 
			   enum pid_type type)

{

	WARN_ON_ONCE(type == PIDTYPE_PID);

	lockdep_assert_held_write(&tasklist_lock);

	hlist_replace_rcu(&old->pid_links[type], &new->pid_links[type]);

}