[PATCH v2 5/9] packet: Remove redundant TAP_BUF_BYTES define

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

Currently we define both TAP_BUF_BYTES and PKT_BUF_BYTES as essentially
the same thing.  They'll be different only if TAP_BUF_BYTES is negative,
which makes no sense.  So, remove TAP_BUF_BYTES and just use PKT_BUF_BYTES.

In addition, most places we use this to just mean the size of the main
packet buffer (pkt_buf) for which we can just directly use sizeof.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 passt.c | 2 +-
 passt.h | 5 ++---
 tap.c   | 4 ++--
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/passt.c b/passt.c
index 0bd2a292..cd067728 100644
--- a/passt.c
+++ b/passt.c
@@ -223,7 +223,7 @@ int main(int argc, char **argv)
 	if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
 		die_perror("Couldn't set disposition for SIGPIPE");
 
-	madvise(pkt_buf, TAP_BUF_BYTES, MADV_HUGEPAGE);
+	madvise(pkt_buf, sizeof(pkt_buf), MADV_HUGEPAGE);
 
 	c.epollfd = epoll_create1(EPOLL_CLOEXEC);
 	if (c.epollfd == -1)
diff --git a/passt.h b/passt.h
index 28d13892..6b248051 100644
--- a/passt.h
+++ b/passt.h
@@ -69,12 +69,11 @@ union epoll_ref {
 static_assert(sizeof(union epoll_ref) <= sizeof(union epoll_data),
 	      "epoll_ref must have same size as epoll_data");
 
-#define TAP_BUF_BYTES							\
+#define PKT_BUF_BYTES							\
 	ROUND_DOWN(((ETH_MAX_MTU + sizeof(uint32_t)) * 128), PAGE_SIZE)
 #define TAP_MSGS							\
-	DIV_ROUND_UP(TAP_BUF_BYTES, ETH_ZLEN - 2 * ETH_ALEN + sizeof(uint32_t))
+	DIV_ROUND_UP(PKT_BUF_BYTES, ETH_ZLEN - 2 * ETH_ALEN + sizeof(uint32_t))
 
-#define PKT_BUF_BYTES		MAX(TAP_BUF_BYTES, 0)
 extern char pkt_buf		[PKT_BUF_BYTES];
 
 extern char *epoll_type_str[];
diff --git a/tap.c b/tap.c
index 4541f51d..fb306e75 100644
--- a/tap.c
+++ b/tap.c
@@ -1080,7 +1080,7 @@ static void tap_passt_input(struct ctx *c, const struct timespec *now)
 
 	do {
 		n = recv(c->fd_tap, pkt_buf + partial_len,
-			 TAP_BUF_BYTES - partial_len, MSG_DONTWAIT);
+			 sizeof(pkt_buf) - partial_len, MSG_DONTWAIT);
 	} while ((n < 0) && errno == EINTR);
 
 	if (n < 0) {
@@ -1151,7 +1151,7 @@ static void tap_pasta_input(struct ctx *c, const struct timespec *now)
 
 	tap_flush_pools();
 
-	for (n = 0; n <= (ssize_t)(TAP_BUF_BYTES - ETH_MAX_MTU); n += len) {
+	for (n = 0; n <= (ssize_t)(sizeof(pkt_buf) - ETH_MAX_MTU); n += len) {
 		len = read(c->fd_tap, pkt_buf + n, ETH_MAX_MTU);
 
 		if (len == 0) {
-- 
@@ -1080,7 +1080,7 @@ static void tap_passt_input(struct ctx *c, const struct timespec *now)
 
 	do {
 		n = recv(c->fd_tap, pkt_buf + partial_len,
-			 TAP_BUF_BYTES - partial_len, MSG_DONTWAIT);
+			 sizeof(pkt_buf) - partial_len, MSG_DONTWAIT);
 	} while ((n < 0) && errno == EINTR);
 
 	if (n < 0) {
@@ -1151,7 +1151,7 @@ static void tap_pasta_input(struct ctx *c, const struct timespec *now)
 
 	tap_flush_pools();
 
-	for (n = 0; n <= (ssize_t)(TAP_BUF_BYTES - ETH_MAX_MTU); n += len) {
+	for (n = 0; n <= (ssize_t)(sizeof(pkt_buf) - ETH_MAX_MTU); n += len) {
 		len = read(c->fd_tap, pkt_buf + n, ETH_MAX_MTU);
 
 		if (len == 0) {
-- 
2.48.1