Re: [PATCH v2 3/3] kthread: Use 'task_struct->full_name' to store kthread's full name

[Bhupesh Sharma]

Hi Kees,

On 4/3/25 9:54 PM, Kees Cook wrote:
> On Mon, Mar 31, 2025 at 05:48:20PM +0530, Bhupesh wrote:
> > Commit 6986ce24fc00 ("kthread: dynamically allocate memory to store
> > kthread's full name"), added 'full_name' in parallel to 'comm' for
> > kthread names.
> >
> > Now that we have added 'full_name' added to 'task_struct' itself,
> > drop the additional 'full_name' entry from 'struct kthread' and also
> > its usage.
> >
> > Signed-off-by: Bhupesh <bhupesh@xxxxxxxxxx>
> I'd like to see this patch be the first patch in the series. This show
> the existing use for "full_name". (And as such it'll probably need bits
> from patch 1.)

Sure, I will fix this in v3.

Thanks,
Bhupesh

> > ---
> >   kernel/kthread.c | 9 +++------
> >   1 file changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/kernel/kthread.c b/kernel/kthread.c
> > index 5dc5b0d7238e..46fe19b7ef76 100644
> > --- a/kernel/kthread.c
> > +++ b/kernel/kthread.c
> > @@ -66,8 +66,6 @@ struct kthread {
> >   #ifdef CONFIG_BLK_CGROUP
> >   	struct cgroup_subsys_state *blkcg_css;
> >   #endif
> > -	/* To store the full name if task comm is truncated. */
> > -	char *full_name;
> >   	struct task_struct *task;
> >   	struct list_head hotplug_node;
> >   	struct cpumask *preferred_affinity;
> > @@ -108,12 +106,12 @@ void get_kthread_comm(char *buf, size_t buf_size, struct task_struct *tsk)
> >   {
> >   	struct kthread *kthread = to_kthread(tsk);
> >   
> > -	if (!kthread || !kthread->full_name) {
> > +	if (!kthread || !tsk->full_name) {
> >   		strscpy(buf, tsk->comm, buf_size);
> >   		return;
> >   	}
> >   
> > -	strscpy_pad(buf, kthread->full_name, buf_size);
> > +	strscpy_pad(buf, tsk->full_name, buf_size);
> >   }
> >   
> >   bool set_kthread_struct(struct task_struct *p)
> > @@ -153,7 +151,6 @@ void free_kthread_struct(struct task_struct *k)
> >   	WARN_ON_ONCE(kthread->blkcg_css);
> >   #endif
> >   	k->worker_private = NULL;
> > -	kfree(kthread->full_name);
> >   	kfree(kthread);
> >   }
> >   
> > @@ -430,7 +427,7 @@ static int kthread(void *_create)
> >   		kthread_exit(-EINTR);
> >   	}
> >   
> > -	self->full_name = create->full_name;
> > +	self->task->full_name = create->full_name;
> >   	self->threadfn = threadfn;
> >   	self->data = data;
> >   
> > --
> > 2.38.1