Re: [PATCH 10/14] can: gw: replace call_rcu by kfree_rcu for simple kmem_cache_free callback
From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: 2024-06-10 13:10:37
Also in:
kernel-janitors, linux-can, lkml
On 09.06.24 10:27, Julia Lawall wrote:
Since SLOB was removed, it is not necessary to use call_rcu
when the callback only performs kmem_cache_free. Use
kfree_rcu() directly.
The changes were done using the following Coccinelle semantic patch.
This semantic patch is designed to ignore cases where the callback
function is used in another way.
// <smpl>
@r@
expression e;
local idexpression e2;
identifier cb,f;
position p;
@@
(
call_rcu(...,e2)
|
call_rcu(&e->f,cb@p)
)
@r1@
type T;
identifier x,r.cb;
@@
cb(...) {
(
kmem_cache_free(...);
|
T x = ...;
kmem_cache_free(...,x);
|
T x;
x = ...;
kmem_cache_free(...,x);
)
}
@s depends on r1@
position p != r.p;
identifier r.cb;
@@
cb@p
@script:ocaml@
cb << r.cb;
p << s.p;
@@
Printf.eprintf "Other use of %s at %s:%d\n"
cb (List.hd p).file (List.hd p).line
@depends on r1 && !s@
expression e;
identifier r.cb,f;
position r.p;
@@
- call_rcu(&e->f,cb@p)
+ kfree_rcu(e,f)
@r1a depends on !s@
type T;
identifier x,r.cb;
@@
- cb(...) {
(
- kmem_cache_free(...);
|
- T x = ...;
- kmem_cache_free(...,x);
|
- T x;
- x = ...;
- kmem_cache_free(...,x);
)
- }
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Vlastimil Babka <redacted>For net/can/gw.c Acked-by: Oliver Hartkopp <socketcan@hartkopp.net> Thanks Julia!
quoted hunk ↗ jump to hunk
--- net/can/gw.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-)diff --git a/net/can/gw.c b/net/can/gw.c index 37528826935e..ffb9870e2d01 100644 --- a/net/can/gw.c +++ b/net/can/gw.c@@ -577,13 +577,6 @@ static inline void cgw_unregister_filter(struct net *net, struct cgw_job *gwj) gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj); } -static void cgw_job_free_rcu(struct rcu_head *rcu_head) -{ - struct cgw_job *gwj = container_of(rcu_head, struct cgw_job, rcu); - - kmem_cache_free(cgw_cache, gwj); -} - static int cgw_notifier(struct notifier_block *nb, unsigned long msg, void *ptr) {@@ -603,7 +596,7 @@ static int cgw_notifier(struct notifier_block *nb, if (gwj->src.dev == dev || gwj->dst.dev == dev) { hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); - call_rcu(&gwj->rcu, cgw_job_free_rcu); + kfree_rcu(gwj, rcu); } } }@@ -1168,7 +1161,7 @@ static void cgw_remove_all_jobs(struct net *net) hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) { hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); - call_rcu(&gwj->rcu, cgw_job_free_rcu); + kfree_rcu(gwj, rcu); } }@@ -1236,7 +1229,7 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh, hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); - call_rcu(&gwj->rcu, cgw_job_free_rcu); + kfree_rcu(gwj, rcu); err = 0; break; }