diff mbox series

[net-next,v5,6/7] tap: Keep hdr_len in tap_get_user()

Message ID 20250205-tun-v5-6-15d0b32e87fa@daynix.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series tun: Unify vnet implementation | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 1 maintainers not CCed: andrew+netdev@lunn.ch
netdev/build_clang success Errors and warnings before: 1 this patch: 1
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 54 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-02-05--09-00 (tests: 886)

Commit Message

Akihiko Odaki Feb. 5, 2025, 6:22 a.m. UTC 
hdr_len is repeatedly used so keep it in a local variable.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 drivers/net/tap.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 5aa41d5f7765a6dcf185bccd3cba2299bad89398..c55c432bac48d395aebc9ceeaa74f7d07e25af4c 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -645,6 +645,7 @@  static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 	int err;
 	struct virtio_net_hdr vnet_hdr = { 0 };
 	int vnet_hdr_len = 0;
+	int hdr_len = 0;
 	int copylen = 0;
 	int depth;
 	bool zerocopy = false;
@@ -663,13 +664,13 @@  static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 		if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
 			goto err;
 		iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
-		if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
-		     tap16_to_cpu(q, vnet_hdr.csum_start) +
-		     tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
-			     tap16_to_cpu(q, vnet_hdr.hdr_len))
-			vnet_hdr.hdr_len = cpu_to_tap16(q,
-				 tap16_to_cpu(q, vnet_hdr.csum_start) +
-				 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
+		hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len);
+		if (vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+			hdr_len = max(tap16_to_cpu(q, vnet_hdr.csum_start) +
+				      tap16_to_cpu(q, vnet_hdr.csum_offset) + 2,
+				      hdr_len);
+			vnet_hdr.hdr_len = cpu_to_tap16(q, hdr_len);
+		}
 		err = -EINVAL;
 		if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
 			goto err;
@@ -682,11 +683,8 @@  static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 	if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
 		struct iov_iter i;
 
-		copylen = vnet_hdr.hdr_len ?
-			tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
-		if (copylen > good_linear)
-			copylen = good_linear;
-		else if (copylen < ETH_HLEN)
+		copylen = min(hdr_len ? hdr_len : GOODCOPY_LEN, good_linear);
+		if (copylen < ETH_HLEN)
 			copylen = ETH_HLEN;
 		linear = copylen;
 		i = *from;
@@ -697,11 +695,9 @@  static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 
 	if (!zerocopy) {
 		copylen = len;
-		linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
-		if (linear > good_linear)
-			linear = good_linear;
-		else if (linear < ETH_HLEN)
-			linear = ETH_HLEN;
+		linear = min(hdr_len, good_linear);
+		if (copylen < ETH_HLEN)
+			copylen = ETH_HLEN;
 	}
 
 	skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,