[PATCH v2 07/12] packet: Remove unhelpful packet_get_try() macro

[David Gibson <david@gibson.dropbear.id.au>]

Two places in the code use the packet_get_try() variant on packet_get().
The difference is that packet_get_try() passes a NULL 'func' to
packet_get_do(), which suppresses log messages.  The places we use this
are ones where we expect to sometimes have a failure retreiving the packet
range, even in normal cases.  So, suppressing the log messages seems like
it makes sense, except:

1) It suppresses log messages on all errors.  We (somewhat) expect to hit
   the case where the requested range is not within the received packet.
   However, it also suppresses message in cases where the requested packet
   index doesn't exist, the requested range has a nonsensical length or
   doesn't lie in even the right vague part of memory.  None of those
   latter cases are expected, and the message would be helpful if we ever
   actually hit them.

2) The suppressed messages aren't actually that disruptive.  For the case
   in ip.c, we'd log only if we run out of IPv6 packet before reaching a
   (non-option) L4 header.  That shouldn't be the case in normal operation
   so getting a message (at trave level) is not unreasonable.
   For the case in dhcpv6.c we do suppress a message every time we look for
   but don't find a specific DHCPv6 option.  That can happen in perfectly
   ok cases, but, again these are trace() level and DHCPv6 transactions
   aren't that common.  Suppressing the message for this case doesn't
   seem worth the drawbacks of (1).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 dhcpv6.c |  2 +-
 ip.c     |  2 +-
 packet.c | 18 +++++-------------
 packet.h |  3 ---
 4 files changed, 7 insertions(+), 18 deletions(-)

diff --git a/dhcpv6.c b/dhcpv6.c
index 0523bba8..c0d05131 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -271,7 +271,7 @@ static struct opt_hdr *dhcpv6_opt(const struct pool *p, size_t *offset,
 	if (!*offset)
 		*offset = sizeof(struct udphdr) + sizeof(struct msg_hdr);
 
-	while ((o = packet_get_try(p, 0, *offset, sizeof(*o), &left))) {
+	while ((o = packet_get(p, 0, *offset, sizeof(*o), &left))) {
 		unsigned int opt_len = ntohs(o->l) + sizeof(*o);
 
 		if (ntohs(o->l) > left)
diff --git a/ip.c b/ip.c
index 2cc7f654..e391f81b 100644
--- a/ip.c
+++ b/ip.c
@@ -51,7 +51,7 @@ char *ipv6_l4hdr(const struct pool *p, int idx, size_t offset, uint8_t *proto,
 	if (!IPV6_NH_OPT(nh))
 		goto found;
 
-	while ((o = packet_get_try(p, idx, offset, sizeof(*o), dlen))) {
+	while ((o = packet_get(p, idx, offset, sizeof(*o), dlen))) {
 		nh = o->nexthdr;
 		hdrlen = (o->hdrlen + 1) * 8;
 
diff --git a/packet.c b/packet.c
index bcac0375..c921aa15 100644
--- a/packet.c
+++ b/packet.c
@@ -112,27 +112,19 @@ void *packet_get_do(const struct pool *p, size_t idx, size_t offset,
 	char *ptr;
 
 	if (idx >= p->size || idx >= p->count) {
-		if (func) {
-			trace("packet %zu from pool size: %zu, count: %zu, "
-			      "%s:%i", idx, p->size, p->count, func, line);
-		}
+		trace("packet %zu from pool size: %zu, count: %zu, %s:%i",
+		      idx, p->size, p->count, func, line);
 		return NULL;
 	}
 
 	if (len > PACKET_MAX_LEN) {
-		if (func) {
-			trace("packet data length %zu, %s:%i",
-			      len, func, line);
-		}
+		trace("packet data length %zu, %s:%i", len, func, line);
 		return NULL;
 	}
 
 	if (len + offset > p->pkt[idx].iov_len) {
-		if (func) {
-			trace("data length %zu, offset %zu from length %zu, "
-			      "%s:%i", len, offset, p->pkt[idx].iov_len,
-			      func, line);
-		}
+		trace("data length %zu, offset %zu from length %zu, %s:%i",
+		      len, offset, p->pkt[idx].iov_len, func, line);
 		return NULL;
 	}
 
diff --git a/packet.h b/packet.h
index 05d37695..f95cda08 100644
--- a/packet.h
+++ b/packet.h
@@ -45,9 +45,6 @@ void pool_flush(struct pool *p);
 #define packet_get(p, idx, offset, len, left)				\
 	packet_get_do(p, idx, offset, len, left, __func__, __LINE__)
 
-#define packet_get_try(p, idx, offset, len, left)			\
-	packet_get_do(p, idx, offset, len, left, NULL, 0)
-
 #define PACKET_POOL_DECL(_name, _size, _buf)				\
 struct _name ## _t {							\
 	char *buf;							\
-- 
@@ -45,9 +45,6 @@ void pool_flush(struct pool *p);
 #define packet_get(p, idx, offset, len, left)				\
 	packet_get_do(p, idx, offset, len, left, __func__, __LINE__)
 
-#define packet_get_try(p, idx, offset, len, left)			\
-	packet_get_do(p, idx, offset, len, left, NULL, 0)
-
 #define PACKET_POOL_DECL(_name, _size, _buf)				\
 struct _name ## _t {							\
 	char *buf;							\
-- 
2.47.1