[PATCH 00/17] replace call_rcu by kfree_rcu for simple kmem_cache_free callback

[Julia Lawall]

Since SLOB was removed and since
commit 6c6c47b063b5 ("mm, slab: call kvfree_rcu_barrier() from kmem_cache_destroy()"),
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>
#spatch --all-includes --include-headers

@r@
expression e;
local idexpression e2;
identifier cb,f,g;
position p;
@@

(
call_rcu(...,e2)
|
call_rcu(&e->f,cb@p)
|
call_rcu(&e->f.g,cb@p)
)

@r1@
type T,T1;
identifier x,r.cb;
@@

 cb(...) {
(
   kmem_cache_free(...);
|
   T x = ...;
   kmem_cache_free(...,(T1)x);
|
   T x;
   x = ...;
   kmem_cache_free(...,(T1)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,g;
position r.p;
@@

(
- call_rcu(&e->f,cb@p)
+ kfree_rcu(e,f)
|
- call_rcu(&e->f.g,cb@p)
+ kfree_rcu(e,f.g)
)

@r1a depends on !s@
type T,T1;
identifier x,r.cb;
@@

- cb(...) {
(
-  kmem_cache_free(...);
|
-  T x = ...;
-  kmem_cache_free(...,(T1)x);
|
-  T x;
-  x = ...;
-  kmem_cache_free(...,(T1)x);
)
- }

@r2 depends on !r1@
identifier r.cb;
@@

cb(...) {
 ...
}

@script:ocaml depends on !r1 && !r2@
cb << r.cb;
@@

Printf.eprintf "need definition for %s\n" cb
// </smpl>

---

 arch/powerpc/kvm/book3s_mmu_hpte.c  |    8 ------
 block/blk-ioc.c                     |    9 ------
 drivers/net/wireguard/allowedips.c  |    9 +-----
 fs/ecryptfs/dentry.c                |    8 ------
 fs/nfsd/nfs4state.c                 |    9 ------
 kernel/time/posix-timers.c          |    9 ------
 net/batman-adv/translation-table.c  |   47 ++----------------------------------
 net/bridge/br_fdb.c                 |    9 ------
 net/can/gw.c                        |   13 ++-------
 net/ipv4/fib_trie.c                 |    8 ------
 net/ipv4/inetpeer.c                 |    9 +-----
 net/ipv6/ip6_fib.c                  |    9 ------
 net/ipv6/xfrm6_tunnel.c             |    8 ------
 net/kcm/kcmsock.c                   |   10 -------
 net/netfilter/nf_conncount.c        |   10 -------
 net/netfilter/nf_conntrack_expect.c |   10 -------
 net/netfilter/xt_hashlimit.c        |    9 ------
 17 files changed, 23 insertions(+), 171 deletions(-)