[RFC PATCH 16/30] net: Prepare nf_log_buf_open() for handling softirq mask

[Frederic Weisbecker <frederic@kernel.org>]

This pair of function is implemented on top of local_bh_disable() that
is going to handle a softirq mask in order to apply finegrained vector
disablement. The lock function is going to return the previous vectors
enabled mask prior to the last call to local_bh_disable(), following a
similar model to that of local_irq_save/restore. Subsequent calls to
local_bh_disable() and friends can then stack up:

	bh = local_bh_disable(vec_mask);
		nf_log_buf_open(&bh2) {
			*bh2 = local_bh_disable(...)
		}
		...
		nf_log_buf_close(bh2) {
			local_bh_enable(bh2);
		}
	local_bh_enable(bh);

To prepare for that, make nf_log_buf_open() able to return a saved vector
enabled mask and pass it back to nf_log_buf_close(). We'll plug it to
local_bh_disable() in a subsequent patch.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/net/netfilter/nf_log.h   | 4 ++--
 net/ipv4/netfilter/nf_log_arp.c  | 5 +++--
 net/ipv4/netfilter/nf_log_ipv4.c | 5 +++--
 net/ipv6/netfilter/nf_log_ipv6.c | 5 +++--
 net/netfilter/nf_log.c           | 4 ++--
 5 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/net/netfilter/nf_log.h b/include/net/netfilter/nf_log.h
index 0d39208..ab55ff9 100644
--- a/include/net/netfilter/nf_log.h
+++ b/include/net/netfilter/nf_log.h
@@ -96,9 +96,9 @@ void nf_log_trace(struct net *net,
 
 struct nf_log_buf;
 
-struct nf_log_buf *nf_log_buf_open(void);
+struct nf_log_buf *nf_log_buf_open(unsigned int *bh);
 __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...);
-void nf_log_buf_close(struct nf_log_buf *m);
+void nf_log_buf_close(struct nf_log_buf *m, unsigned int bh);
 
 /* common logging functions */
 int nf_log_dump_udp_header(struct nf_log_buf *m, const struct sk_buff *skb,
diff --git a/net/ipv4/netfilter/nf_log_arp.c b/net/ipv4/netfilter/nf_log_arp.c
index df5c2a2..3696911 100644
--- a/net/ipv4/netfilter/nf_log_arp.c
+++ b/net/ipv4/netfilter/nf_log_arp.c
@@ -85,12 +85,13 @@ static void nf_log_arp_packet(struct net *net, u_int8_t pf,
 			      const char *prefix)
 {
 	struct nf_log_buf *m;
+	unsigned int bh;
 
 	/* FIXME: Disabled from containers until syslog ns is supported */
 	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
 		return;
 
-	m = nf_log_buf_open();
+	m = nf_log_buf_open(&bh);
 
 	if (!loginfo)
 		loginfo = &default_loginfo;
@@ -99,7 +100,7 @@ static void nf_log_arp_packet(struct net *net, u_int8_t pf,
 				  prefix);
 	dump_arp_packet(m, loginfo, skb, 0);
 
-	nf_log_buf_close(m);
+	nf_log_buf_close(m, bh);
 }
 
 static struct nf_logger nf_arp_logger __read_mostly = {
diff --git a/net/ipv4/netfilter/nf_log_ipv4.c b/net/ipv4/netfilter/nf_log_ipv4.c
index 1e6f28c..996f386 100644
--- a/net/ipv4/netfilter/nf_log_ipv4.c
+++ b/net/ipv4/netfilter/nf_log_ipv4.c
@@ -317,12 +317,13 @@ static void nf_log_ip_packet(struct net *net, u_int8_t pf,
 			     const char *prefix)
 {
 	struct nf_log_buf *m;
+	unsigned int bh;
 
 	/* FIXME: Disabled from containers until syslog ns is supported */
 	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
 		return;
 
-	m = nf_log_buf_open();
+	m = nf_log_buf_open(&bh);
 
 	if (!loginfo)
 		loginfo = &default_loginfo;
@@ -335,7 +336,7 @@ static void nf_log_ip_packet(struct net *net, u_int8_t pf,
 
 	dump_ipv4_packet(net, m, loginfo, skb, 0);
 
-	nf_log_buf_close(m);
+	nf_log_buf_close(m, bh);
 }
 
 static struct nf_logger nf_ip_logger __read_mostly = {
diff --git a/net/ipv6/netfilter/nf_log_ipv6.c b/net/ipv6/netfilter/nf_log_ipv6.c
index c6bf580..62bff78 100644
--- a/net/ipv6/netfilter/nf_log_ipv6.c
+++ b/net/ipv6/netfilter/nf_log_ipv6.c
@@ -349,12 +349,13 @@ static void nf_log_ip6_packet(struct net *net, u_int8_t pf,
 			      const char *prefix)
 {
 	struct nf_log_buf *m;
+	unsigned int bh;
 
 	/* FIXME: Disabled from containers until syslog ns is supported */
 	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
 		return;
 
-	m = nf_log_buf_open();
+	m = nf_log_buf_open(&bh);
 
 	if (!loginfo)
 		loginfo = &default_loginfo;
@@ -367,7 +368,7 @@ static void nf_log_ip6_packet(struct net *net, u_int8_t pf,
 
 	dump_ipv6_packet(net, m, loginfo, skb, skb_network_offset(skb), 1);
 
-	nf_log_buf_close(m);
+	nf_log_buf_close(m, bh);
 }
 
 static struct nf_logger nf_ip6_logger __read_mostly = {
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index a61d6df..06ded8a31 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -292,7 +292,7 @@ __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
 }
 EXPORT_SYMBOL_GPL(nf_log_buf_add);
 
-struct nf_log_buf *nf_log_buf_open(void)
+struct nf_log_buf *nf_log_buf_open(unsigned int *bh)
 {
 	struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
 
@@ -307,7 +307,7 @@ struct nf_log_buf *nf_log_buf_open(void)
 }
 EXPORT_SYMBOL_GPL(nf_log_buf_open);
 
-void nf_log_buf_close(struct nf_log_buf *m)
+void nf_log_buf_close(struct nf_log_buf *m, unsigned int bh)
 {
 	m->buf[m->count] = 0;
 	printk("%s\n", m->buf);
-- 
2.7.4