From 31bf9bae378fe6fc37e03f00805eea9300376006 Mon Sep 17 00:00:00 2001
From: Divya Sharma <divyash@codeaurora.org>
Date: Tue, 6 Oct 2020 08:15:33 -0700
Subject: [PATCH] Revert "rmnet_core: Check for contiguous QMAP headers during
 deaggregation"

This reverts commit df2d62bed079908c127051de3385f3560c5f8c90.

Change-Id: Icc987d5f1ba74199f420e2ee65902d8e60e4fda9
---
 core/rmnet_descriptor.c | 40 +++++++---------------------------------
 1 file changed, 7 insertions(+), 33 deletions(-)

diff --git a/core/rmnet_descriptor.c b/core/rmnet_descriptor.c
index 79612ec49cd3..c0b95f330c4c 100644
--- a/core/rmnet_descriptor.c
+++ b/core/rmnet_descriptor.c
@@ -558,36 +558,20 @@ int rmnet_frag_flow_command(struct rmnet_frag_descriptor *frag_desc,
 }
 EXPORT_SYMBOL(rmnet_frag_flow_command);
 
-static int rmnet_frag_deaggregate_one(struct sk_buff *skb,
+static int rmnet_frag_deaggregate_one(struct skb_shared_info *shinfo,
 				      struct rmnet_port *port,
 				      struct list_head *list,
 				      u32 start_frag)
 {
-	struct skb_shared_info *shinfo = skb_shinfo(skb);
 	struct rmnet_frag_descriptor *frag_desc;
-	struct rmnet_map_header *maph, __maph;
+	struct rmnet_map_header *maph;
 	skb_frag_t *frag;
 	u32 i;
 	u32 pkt_len;
 	int rc;
 
 	frag = &shinfo->frags[start_frag];
-	/* Grab the QMAP header. Careful, as there's no guarantee that it's
-	 * continugous!
-	 */
-	if (likely(skb_frag_size(frag) >= sizeof(*maph))) {
-		maph = skb_frag_address(frag);
-	} else {
-		/* The header's split across pages. We can rebuild it.
-		 * Probably not faster or stronger than before. But certainly
-		 * more linear.
-		 */
-		if (skb_copy_bits(skb, 0, &__maph, sizeof(&__maph)) < 0)
-			return -1;
-
-		maph = &__maph;
-	}
-
+	maph = skb_frag_address(frag);
 	pkt_len = ntohs(maph->pkt_len);
 	/* Catch empty frames */
 	if (!pkt_len)
@@ -606,19 +590,9 @@ static int rmnet_frag_deaggregate_one(struct sk_buff *skb,
 		u32 hsize = 0;
 		u8 type;
 
-		/* Check the type. This seems like should be overkill for less
-		 * than a single byte, doesn't it?
-		 */
-		if (likely(skb_frag_size(frag) >= sizeof(*maph) + 1)) {
-			type = *((u8 *)maph + sizeof(*maph));
-		} else {
-			if (skb_copy_bits(skb, sizeof(*maph), &type,
-					  sizeof(type)) < 0)
-				return -1;
-		}
-
-		/* Type only uses the first 7 bits */
-		switch ((type & 0xFE) >> 1) {
+		type = ((struct rmnet_map_v5_coal_header *)
+			(maph + 1))->header_type;
+		switch (type) {
 		case RMNET_MAP_HEADER_TYPE_COALESCING:
 			hsize = sizeof(struct rmnet_map_v5_coal_header);
 			break;
@@ -673,7 +647,7 @@ void rmnet_frag_deaggregate(struct sk_buff *skb, struct rmnet_port *port,
 	int rc;
 
 	while (i < shinfo->nr_frags) {
-		rc = rmnet_frag_deaggregate_one(skb, port, list, i);
+		rc = rmnet_frag_deaggregate_one(shinfo, port, list, i);
 		if (rc < 0)
 			return;