On Wed, Feb 5, 2025 at 9:27 PM Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> wrote: > > * Mateusz Guzik <mjguzik@xxxxxxxxx> [250205 14:33]: > > If a patch is worth doing, it's worth explaining. I'm surprised you > didn't add a comment after the last revision missed a comment on patch > 2/6. This is literally in the submitting patches document [1]. > > I don't mean to delay this series, but I do want to know why things are > done when I'm hunting through git logs. Having a change log isn't > optional, and now you know that Andrews script won't fix this problem > [2]. > > I see you are upset by this considering the terse and lack of > punctuation in patch 2, but please try to understand these comments > serve a purpose in maintaining the code years later. > I'm not upset. For this specific case I don't know what can be written in the body given the really self-explanatory nature of the change, other than to spell it out(?). Does this work for you: The routines need to be called with the tasklist_lock, the asserts validate at runtime that this holds. I also git log a lot and like to know what's up, to that end I appreciate *short* commit messages so that I know there is nothing more to the patch than meets the eye. In particular if there is nothing of value to add in the body, I appreciate if there is none. But that's me, I'm not going to insist one way or the other. > [1]. https://www.kernel.org/doc/html/v6.12/process/submitting-patches.html#describe-your-changes > [2]. https://lore.kernel.org/all/20250203175128.80319b42c9739f0d420080a4@xxxxxxxxxxxxxxxxxxxx/ > > > Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx> > > Signed-off-by: Mateusz Guzik <mjguzik@xxxxxxxxx> > > --- > > kernel/pid.c | 15 ++++++++++++--- > > 1 file changed, 12 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/pid.c b/kernel/pid.c > > index 924084713be8..2ae872f689a7 100644 > > --- a/kernel/pid.c > > +++ b/kernel/pid.c > > @@ -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]); > > } > > > > -- > > 2.43.0 > > > > -- Mateusz Guzik <mjguzik gmail.com>
