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, 17 insertions, 23 deletions

diff --git a/net/sctp/output.c b/net/sctp/output.c
index bbef4a7..a46d1eb 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -93,8 +93,7 @@ struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
 {
 	struct sctp_chunk *chunk = NULL;
 
-	SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__,
-			  packet, vtag);
+	pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag);
 
 	packet->vtag = vtag;
 
@@ -119,8 +118,7 @@ struct sctp_packet *sctp_packet_init(struct sctp_packet *packet,
 	struct sctp_association *asoc = transport->asoc;
 	size_t overhead;
 
-	SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__,
-			  packet, transport);
+	pr_debug("%s: packet:%p transport:%p\n", __func__, packet, transport);
 
 	packet->transport = transport;
 	packet->source_port = sport;
@@ -145,7 +143,7 @@ void sctp_packet_free(struct sctp_packet *packet)
 {
 	struct sctp_chunk *chunk, *tmp;
 
-	SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet);
+	pr_debug("%s: packet:%p\n", __func__, packet);
 
 	list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
 		list_del_init(&chunk->list);
@@ -167,8 +165,7 @@ sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet,
 	sctp_xmit_t retval;
 	int error = 0;
 
-	SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__,
-			  packet, chunk);
+	pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk);
 
 	switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) {
 	case SCTP_XMIT_PMTU_FULL:
@@ -334,8 +331,7 @@ sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet,
 {
 	sctp_xmit_t retval = SCTP_XMIT_OK;
 
-	SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, packet,
-			  chunk);
+	pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk);
 
 	/* Data chunks are special.  Before seeing what else we can
 	 * bundle into this packet, check to see if we are allowed to
@@ -402,7 +398,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	unsigned char *auth = NULL;	/* pointer to auth in skb data */
 	__u32 cksum_buf_len = sizeof(struct sctphdr);
 
-	SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet);
+	pr_debug("%s: packet:%p\n", __func__, packet);
 
 	/* Do NOT generate a chunkless packet. */
 	if (list_empty(&packet->chunk_list))
@@ -472,7 +468,9 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	 *
 	 * [This whole comment explains WORD_ROUND() below.]
 	 */
-	SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n");
+
+	pr_debug("***sctp_transmit_packet***\n");
+
 	list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
 		list_del_init(&chunk->list);
 		if (sctp_chunk_is_data(chunk)) {
@@ -505,16 +503,13 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 		memcpy(skb_put(nskb, chunk->skb->len),
 			       chunk->skb->data, chunk->skb->len);
 
-		SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n",
-				  "*** Chunk", chunk,
-				  sctp_cname(SCTP_ST_CHUNK(
-					  chunk->chunk_hdr->type)),
-				  chunk->has_tsn ? "TSN" : "No TSN",
-				  chunk->has_tsn ?
-				  ntohl(chunk->subh.data_hdr->tsn) : 0,
-				  "length", ntohs(chunk->chunk_hdr->length),
-				  "chunk->skb->len", chunk->skb->len,
-				  "rtt_in_progress", chunk->rtt_in_progress);
+		pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, "
+			 "rtt_in_progress:%d\n", chunk,
+			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
+			 chunk->has_tsn ? "TSN" : "No TSN",
+			 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
+			 ntohs(chunk->chunk_hdr->length), chunk->skb->len,
+			 chunk->rtt_in_progress);
 
 		/*
 		 * If this is a control chunk, this is our last
@@ -606,8 +601,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 		}
 	}
 
-	SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n",
-			  nskb->len);
+	pr_debug("***sctp_transmit_packet*** skb->len:%d\n", nskb->len);
 
 	nskb->local_df = packet->ipfragok;
 	(*tp->af_specific->sctp_xmit)(nskb, tp);