From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935664AbcKONQS (ORCPT ); Tue, 15 Nov 2016 08:16:18 -0500 Received: from Chamillionaire.breakpoint.cc ([146.0.238.67]:42978 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932407AbcKONQO (ORCPT ); Tue, 15 Nov 2016 08:16:14 -0500 From: Florian Westphal To: linux-kernel@vger.kernel.org Cc: linux-audit@redhat.com, paul@paul-moore.com, eparis@redhat.com, Florian Westphal Subject: [PATCH] audit: remove the audit freelist Date: Tue, 15 Nov 2016 14:16:14 +0100 Message-Id: <1479215774-29810-1-git-send-email-fw@strlen.de> X-Mailer: git-send-email 2.7.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org allows better debugging as freeing audit buffers now always honors slub debug hooks (e.g. object poisoning) and leak checker can detect the free operation. Removal also results in a small speedup (using single rule 'iptables -A INPUT -i lo -j AUDIT --type drop'): super_netperf 4 -H 127.0.0.1 -l 360 -t UDP_RR -- -R 1 -m 64 Before: 294953 After: 298013 (alloc/free no longer serializes on spinlock, allocator can use percpu pool). Signed-off-by: Florian Westphal --- kernel/audit.c | 53 ++++++++--------------------------------------------- 1 file changed, 8 insertions(+), 45 deletions(-) diff --git a/kernel/audit.c b/kernel/audit.c index f1ca11613379..396868dc523a 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -131,13 +131,6 @@ static int audit_net_id; /* Hash for inode-based rules */ struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; -/* The audit_freelist is a list of pre-allocated audit buffers (if more - * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of - * being placed on the freelist). */ -static DEFINE_SPINLOCK(audit_freelist_lock); -static int audit_freelist_count; -static LIST_HEAD(audit_freelist); - static struct sk_buff_head audit_skb_queue; /* queue of skbs to send to auditd when/if it comes back */ static struct sk_buff_head audit_skb_hold_queue; @@ -164,17 +157,11 @@ DEFINE_MUTEX(audit_cmd_mutex); * should be at least that large. */ #define AUDIT_BUFSIZ 1024 -/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the - * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ -#define AUDIT_MAXFREE (2*NR_CPUS) - -/* The audit_buffer is used when formatting an audit record. The caller - * locks briefly to get the record off the freelist or to allocate the - * buffer, and locks briefly to send the buffer to the netlink layer or +/* The audit_buffer is used when formatting an audit record. + * The caller locks briefly to send the buffer to the netlink layer or * to place it on a transmit queue. Multiple audit_buffers can be in * use simultaneously. */ struct audit_buffer { - struct list_head list; struct sk_buff *skb; /* formatted skb ready to send */ struct audit_context *ctx; /* NULL or associated context */ gfp_t gfp_mask; @@ -1247,43 +1234,22 @@ __setup("audit_backlog_limit=", audit_backlog_limit_set); static void audit_buffer_free(struct audit_buffer *ab) { - unsigned long flags; - if (!ab) return; kfree_skb(ab->skb); - spin_lock_irqsave(&audit_freelist_lock, flags); - if (audit_freelist_count > AUDIT_MAXFREE) - kfree(ab); - else { - audit_freelist_count++; - list_add(&ab->list, &audit_freelist); - } - spin_unlock_irqrestore(&audit_freelist_lock, flags); + kfree(ab); } static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, gfp_t gfp_mask, int type) { - unsigned long flags; - struct audit_buffer *ab = NULL; + struct audit_buffer *ab; struct nlmsghdr *nlh; - spin_lock_irqsave(&audit_freelist_lock, flags); - if (!list_empty(&audit_freelist)) { - ab = list_entry(audit_freelist.next, - struct audit_buffer, list); - list_del(&ab->list); - --audit_freelist_count; - } - spin_unlock_irqrestore(&audit_freelist_lock, flags); - - if (!ab) { - ab = kmalloc(sizeof(*ab), gfp_mask); - if (!ab) - goto err; - } + ab = kmalloc(sizeof(*ab), gfp_mask); + if (!ab) + return NULL; ab->ctx = ctx; ab->gfp_mask = gfp_mask; @@ -1294,13 +1260,10 @@ static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0); if (!nlh) - goto out_kfree_skb; + goto err; return ab; -out_kfree_skb: - kfree_skb(ab->skb); - ab->skb = NULL; err: audit_buffer_free(ab); return NULL; -- 2.7.3