net: sctp: rework debugging framework to use pr_debug and friends

We should get rid of all own SCTP debug printk macros and use the ones
that the kernel offers anyway instead. This makes the code more readable
and conform to the kernel code, and offers all the features of dynamic
debbuging that pr_debug() et al has, such as only turning on/off portions
of debug messages at runtime through debugfs. The runtime cost of having
CONFIG_DYNAMIC_DEBUG enabled, but none of the debug statements printing,
is negligible [1]. If kernel debugging is completly turned off, then these
statements will also compile into "empty" functions.

While we're at it, we also need to change the Kconfig option as it /now/
only refers to the ifdef'ed code portions in outqueue.c that enable further
debugging/tracing of SCTP transaction fields. Also, since SCTP_ASSERT code
was enabled with this Kconfig option and has now been removed, we
transform those code parts into WARNs resp. where appropriate BUG_ONs so
that those bugs can be more easily detected as probably not many people
have SCTP debugging permanently turned on.

To turn on all SCTP debugging, the following steps are needed:

 # mount -t debugfs none /sys/kernel/debug
 # echo -n 'module sctp +p' > /sys/kernel/debug/dynamic_debug/control

This can be done more fine-grained on a per file, per line basis and others
as described in [2].

 [1] https://www.kernel.org/doc/ols/2009/ols2009-pages-39-46.pdf
 [2] Documentation/dynamic-debug-howto.txt

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 9 deletions

diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index adeaa0e64f52..09ffcc912d23 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -239,9 +239,8 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *transport)
 		fl6.daddr = *rt0->addr;
 	}
 
-	SCTP_DEBUG_PRINTK("%s: skb:%p, len:%d, src:%pI6 dst:%pI6\n",
-			  __func__, skb, skb->len,
-			  &fl6.saddr, &fl6.daddr);
+	pr_debug("%s: skb:%p, len:%d, src:%pI6 dst:%pI6\n", __func__, skb,
+		 skb->len, &fl6.saddr, &fl6.daddr);
 
 	SCTP_INC_STATS(sock_net(sk), SCTP_MIB_OUTSCTPPACKS);
 
@@ -276,7 +275,7 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 	if (ipv6_addr_type(&daddr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
 		fl6->flowi6_oif = daddr->v6.sin6_scope_id;
 
-	SCTP_DEBUG_PRINTK("%s: DST=%pI6 ", __func__, &fl6->daddr);
+	pr_debug("%s: dst=%pI6 ", __func__, &fl6->daddr);
 
 	if (asoc)
 		fl6->fl6_sport = htons(asoc->base.bind_addr.port);
@@ -284,7 +283,8 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 	if (saddr) {
 		fl6->saddr = saddr->v6.sin6_addr;
 		fl6->fl6_sport = saddr->v6.sin6_port;
-		SCTP_DEBUG_PRINTK("SRC=%pI6 - ", &fl6->saddr);
+
+		pr_debug("src=%pI6 - ", &fl6->saddr);
 	}
 
 	dst = ip6_dst_lookup_flow(sk, fl6, NULL, false);
@@ -348,13 +348,16 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 out:
 	if (!IS_ERR_OR_NULL(dst)) {
 		struct rt6_info *rt;
+
 		rt = (struct rt6_info *)dst;
 		t->dst = dst;
-		SCTP_DEBUG_PRINTK("rt6_dst:%pI6 rt6_src:%pI6\n",
-			&rt->rt6i_dst.addr, &fl6->saddr);
+
+		pr_debug("rt6_dst:%pI6 rt6_src:%pI6\n", &rt->rt6i_dst.addr,
+			 &fl6->saddr);
 	} else {
 		t->dst = NULL;
-		SCTP_DEBUG_PRINTK("NO ROUTE\n");
+
+		pr_debug("no route\n");
 	}
 }
 
@@ -377,7 +380,7 @@ static void sctp_v6_get_saddr(struct sctp_sock *sk,
 	struct flowi6 *fl6 = &fl->u.ip6;
 	union sctp_addr *saddr = &t->saddr;
 
-	SCTP_DEBUG_PRINTK("%s: asoc:%p dst:%p\n", __func__, t->asoc, t->dst);
+	pr_debug("%s: asoc:%p dst:%p\n", __func__, t->asoc, t->dst);
 
 	if (t->dst) {
 		saddr->v6.sin6_family = AF_INET6;