On Mon, 27 May 2024, Paul E. McKenney wrote:
> On Mon, May 27, 2024 at 10:13:40AM +0200, Julia Lawall wrote:
> >
> >
> > On Mon, 27 May 2024, Vlastimil Babka wrote:
> >
> > > Hi,
> > >
> > > one bit from LSF/MM discussions is that there might be call_rcu users
> > > with a
> > > callback that only does a kmem_cache_free() to a specific cache. Since
> > > SLOB
> > > was removed, it's always ok to use kfree() and thus also kfree_rcu() on
> > > allocations from kmem_cache_alloc() in addition to kmalloc(). Thus, such
> > > call_rcu() users might be simplified to kfree_rcu(). I found some cases
> > > semi-manually, but I'd expect coccinelle could help here so if anyone
> > > wants
> > > to take this task, feel free to.
> >
> > Thanks for the suggestion! I will try to look into it.
>
> Thank you both!
I found the following functions. Do you want some other information, such
as where they are called from?
Ignore the -s at the beginning of some lines. Those are for emphasis. not
to suggest to remove the code.
I checked that the functions are only used in calls to call_rcu.
Without more effort, Coccinelle only looks for functions defined in the
same file. Here are the functions that are passed to call_rcu where the
function is not defined in the same file:
need definition for audit_free_rule_rcu
need definition for __i915_gem_free_object_rcu
need definition for io_eventfd_ops
need definition for ip_vs_dest_dst_rcu_free
need definition for __put_task_struct_rcu_cb
need definition for radix_tree_node_rcu_free
They all do something more, although radix_tree_node_rcu_free doesn't do
much more (some memsets).
julia
diff -u -p /home/jll/linux/drivers/net/wireguard/allowedips.c
/tmp/nothing/drivers/net/wireguard/allowedips.c
--- /home/jll/linux/drivers/net/wireguard/allowedips.c
+++ /tmp/nothing/drivers/net/wireguard/allowedips.c
@@ -50,7 +50,6 @@ static void push_rcu(struct allowedips_n
static void node_free_rcu(struct rcu_head *rcu)
{
- kmem_cache_free(node_cache, container_of(rcu, struct allowedips_node,
rcu));
}
static void root_free_rcu(struct rcu_head *rcu)
diff -u -p /home/jll/linux/fs/ecryptfs/dentry.c
/tmp/nothing/fs/ecryptfs/dentry.c
--- /home/jll/linux/fs/ecryptfs/dentry.c
+++ /tmp/nothing/fs/ecryptfs/dentry.c
@@ -53,8 +53,6 @@ struct kmem_cache *ecryptfs_dentry_info_
static void ecryptfs_dentry_free_rcu(struct rcu_head *head)
{
- kmem_cache_free(ecryptfs_dentry_info_cache,
- container_of(head, struct ecryptfs_dentry_info, rcu));
}
/**
diff -u -p /home/jll/linux/kernel/fork.c /tmp/nothing/kernel/fork.c
--- /home/jll/linux/kernel/fork.c
+++ /tmp/nothing/kernel/fork.c
@@ -378,7 +378,6 @@ static struct kmem_cache *thread_stack_c
static void thread_stack_free_rcu(struct rcu_head *rh)
{
- kmem_cache_free(thread_stack_cache, rh);
}
static void thread_stack_delayed_free(struct task_struct *tsk)
diff -u -p /home/jll/linux/kernel/workqueue.c /tmp/nothing/kernel/workqueue.c
--- /home/jll/linux/kernel/workqueue.c
+++ /tmp/nothing/kernel/workqueue.c
@@ -5024,8 +5024,6 @@ fail:
static void rcu_free_pwq(struct rcu_head *rcu)
{
- kmem_cache_free(pwq_cache,
- container_of(rcu, struct pool_workqueue, rcu));
}
/*
diff -u -p /home/jll/linux/net/ipv4/inetpeer.c /tmp/nothing/net/ipv4/inetpeer.c
--- /home/jll/linux/net/ipv4/inetpeer.c
+++ /tmp/nothing/net/ipv4/inetpeer.c
@@ -130,7 +130,6 @@ static struct inet_peer *lookup(const st
static void inetpeer_free_rcu(struct rcu_head *head)
{
- kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu));
}
/* perform garbage collect on all items stacked during a lookup */
diff -u -p /home/jll/linux/net/ipv6/xfrm6_tunnel.c
/tmp/nothing/net/ipv6/xfrm6_tunnel.c
--- /home/jll/linux/net/ipv6/xfrm6_tunnel.c
+++ /tmp/nothing/net/ipv6/xfrm6_tunnel.c
@@ -180,8 +180,6 @@ EXPORT_SYMBOL(xfrm6_tunnel_alloc_spi);
static void x6spi_destroy_rcu(struct rcu_head *head)
{
- kmem_cache_free(xfrm6_tunnel_spi_kmem,
- container_of(head, struct xfrm6_tunnel_spi, rcu_head));
}
static void xfrm6_tunnel_free_spi(struct net *net, xfrm_address_t *saddr)
diff -u -p /home/jll/linux/security/security.c /tmp/nothing/security/security.c
--- /home/jll/linux/security/security.c
+++ /tmp/nothing/security/security.c
@@ -1599,7 +1599,6 @@ static void inode_free_by_rcu(struct rcu
/*
* The rcu head is at the start of the inode blob
*/
- kmem_cache_free(lsm_inode_cache, head);
}
/**
