linux/fs/dlm/memory.c
Alexander Aring 89b01913dc dlm: add rcu_barrier before destroy kmem cache
In the case we trigger dlm_free_rsb() that does a call_rcu() and the
responding kfree() of res_lvbptr and a kmem_cache_free() of the rsb
pointer we need to wait until this pending operation is done before
calling kmem_cache_destroy(). We doing that by using rcu_barrier() that
waits until all pending call_rcu() are done. This avoids that
kmem_cache_destroy() complains about active objects around that are not
being freed yet by call_rcu().

There is currently more discussions about to make this behaviour better,
see:

https://lore.kernel.org/netdev/20240609082726.32742-1-Julia.Lawall@inria.fr/

However this is only for call_rcu() if the callback calls
kmem_cache_destroy() only to replace it by kfree_rcu() call which has
currently some issue. This isn't our case because we also free the
res_lvbptr if being set.

For our case, to avoid the above race rcu_barrier() should be used before
calling kmem_cache_destroy() to be sure that there are no active objects
around. This is exactly what net/batman-adv is also doing before calling their
kmem_cache_destroy() in module unloading.

Fixes: 01fdeca1cc ("dlm: use rcu to avoid an extra rsb struct lookup")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2024-06-13 12:48:46 -05:00

180 lines
3.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
** Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
**
**
*******************************************************************************
******************************************************************************/
#include "dlm_internal.h"
#include "midcomms.h"
#include "lowcomms.h"
#include "config.h"
#include "memory.h"
#include "ast.h"
static struct kmem_cache *writequeue_cache;
static struct kmem_cache *mhandle_cache;
static struct kmem_cache *msg_cache;
static struct kmem_cache *lkb_cache;
static struct kmem_cache *rsb_cache;
static struct kmem_cache *cb_cache;
int __init dlm_memory_init(void)
{
writequeue_cache = dlm_lowcomms_writequeue_cache_create();
if (!writequeue_cache)
goto out;
mhandle_cache = dlm_midcomms_cache_create();
if (!mhandle_cache)
goto mhandle;
lkb_cache = kmem_cache_create("dlm_lkb", sizeof(struct dlm_lkb),
__alignof__(struct dlm_lkb), 0, NULL);
if (!lkb_cache)
goto lkb;
msg_cache = dlm_lowcomms_msg_cache_create();
if (!msg_cache)
goto msg;
rsb_cache = kmem_cache_create("dlm_rsb", sizeof(struct dlm_rsb),
__alignof__(struct dlm_rsb), 0, NULL);
if (!rsb_cache)
goto rsb;
cb_cache = kmem_cache_create("dlm_cb", sizeof(struct dlm_callback),
__alignof__(struct dlm_callback), 0,
NULL);
if (!cb_cache)
goto cb;
return 0;
cb:
kmem_cache_destroy(rsb_cache);
rsb:
kmem_cache_destroy(msg_cache);
msg:
kmem_cache_destroy(lkb_cache);
lkb:
kmem_cache_destroy(mhandle_cache);
mhandle:
kmem_cache_destroy(writequeue_cache);
out:
return -ENOMEM;
}
void dlm_memory_exit(void)
{
rcu_barrier();
kmem_cache_destroy(writequeue_cache);
kmem_cache_destroy(mhandle_cache);
kmem_cache_destroy(msg_cache);
kmem_cache_destroy(lkb_cache);
kmem_cache_destroy(rsb_cache);
kmem_cache_destroy(cb_cache);
}
char *dlm_allocate_lvb(struct dlm_ls *ls)
{
char *p;
p = kzalloc(ls->ls_lvblen, GFP_ATOMIC);
return p;
}
void dlm_free_lvb(char *p)
{
kfree(p);
}
struct dlm_rsb *dlm_allocate_rsb(struct dlm_ls *ls)
{
struct dlm_rsb *r;
r = kmem_cache_zalloc(rsb_cache, GFP_ATOMIC);
return r;
}
static void __free_rsb_rcu(struct rcu_head *rcu)
{
struct dlm_rsb *r = container_of(rcu, struct dlm_rsb, rcu);
if (r->res_lvbptr)
dlm_free_lvb(r->res_lvbptr);
kmem_cache_free(rsb_cache, r);
}
void dlm_free_rsb(struct dlm_rsb *r)
{
call_rcu(&r->rcu, __free_rsb_rcu);
}
struct dlm_lkb *dlm_allocate_lkb(struct dlm_ls *ls)
{
struct dlm_lkb *lkb;
lkb = kmem_cache_zalloc(lkb_cache, GFP_ATOMIC);
return lkb;
}
void dlm_free_lkb(struct dlm_lkb *lkb)
{
if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
struct dlm_user_args *ua;
ua = lkb->lkb_ua;
if (ua) {
kfree(ua->lksb.sb_lvbptr);
kfree(ua);
}
}
kmem_cache_free(lkb_cache, lkb);
}
struct dlm_mhandle *dlm_allocate_mhandle(void)
{
return kmem_cache_alloc(mhandle_cache, GFP_ATOMIC);
}
void dlm_free_mhandle(struct dlm_mhandle *mhandle)
{
kmem_cache_free(mhandle_cache, mhandle);
}
struct writequeue_entry *dlm_allocate_writequeue(void)
{
return kmem_cache_alloc(writequeue_cache, GFP_ATOMIC);
}
void dlm_free_writequeue(struct writequeue_entry *writequeue)
{
kmem_cache_free(writequeue_cache, writequeue);
}
struct dlm_msg *dlm_allocate_msg(void)
{
return kmem_cache_alloc(msg_cache, GFP_ATOMIC);
}
void dlm_free_msg(struct dlm_msg *msg)
{
kmem_cache_free(msg_cache, msg);
}
struct dlm_callback *dlm_allocate_cb(void)
{
return kmem_cache_alloc(cb_cache, GFP_ATOMIC);
}
void dlm_free_cb(struct dlm_callback *cb)
{
kmem_cache_free(cb_cache, cb);
}