Re: [PATCH 05/14] tracefs: replace call_rcu by kfree_rcu for simple kmem_cache_free callback

Paul E. McKenney
2024-06-10T15:46:42Z

On Mon, Jun 10, 2024 at 11:22:23AM -0400, Steven Rostedt wrote:
> On Sun, 9 Jun 2024 10:27:17 +0200
> Julia Lawall <Julia.Lawall@inria.fr> wrote:
>
> > diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
> > index 7c29f4afc23d..338c52168e61 100644
> > --- a/fs/tracefs/inode.c
> > +++ b/fs/tracefs/inode.c
> > @@ -53,14 +53,6 @@ static struct inode *tracefs_alloc_inode(struct super_block *sb)
> > return &ti->vfs_inode;
> > }
> >
> > -static void tracefs_free_inode_rcu(struct rcu_head *rcu)
> > -{
> > - struct tracefs_inode *ti;
> > -
> > - ti = container_of(rcu, struct tracefs_inode, rcu);
> > - kmem_cache_free(tracefs_inode_cachep, ti);
>
> Does this work?
>
> tracefs needs to be freed via the tracefs_inode_cachep. Does
> kfree_rcu() handle specific frees for objects that were not allocated
> via kmalloc()?

A recent change to kfree() allows it to correctly handle memory allocated
via kmem_cache_alloc(). News to me as of a few weeks ago. ;-)

Thanx, Paul

> -- Steve
>
>
> > -}
> > -
> > static void tracefs_free_inode(struct inode *inode)
> > {
> > struct tracefs_inode *ti = get_tracefs(inode);
> > @@ -70,7 +62,7 @@ static void tracefs_free_inode(struct inode *inode)
> > list_del_rcu(&ti->list);
> > spin_unlock_irqrestore(&tracefs_inode_lock, flags);
> >
> > - call_rcu(&ti->rcu, tracefs_free_inode_rcu);
> > + kfree_rcu(ti, rcu);
> > }
> >
> > static ssize_t default_read_file(struct file *file, char __user *buf,
>