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Subject[PATCH 5.2 048/143] mt76: usb: fix rx A-MSDU support
Date
[ Upstream commit 2a92b08b18553c101115423bd34963b1a59a45a3 ]

Commit f8f527b16db5 ("mt76: usb: use EP max packet aligned buffer sizes
for rx") breaks A-MSDU support. When A-MSDU is enable the device can
receive frames up to q->buf_size but they will be discarded in
mt76u_process_rx_entry since there is no enough room for
skb_shared_info. Fix the issue reallocating the skb and copying in the
linear area the first 128B of the received frames and in the frag_list
the remaining part

Fixes: f8f527b16db5 ("mt76: usb: use EP max packet aligned buffer sizes for rx")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/mediatek/mt76/mt76.h | 1 +
drivers/net/wireless/mediatek/mt76/usb.c | 46 ++++++++++++++++++-----
2 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 8ecbf81a906f5..889b76deb7037 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -30,6 +30,7 @@
#define MT_TX_RING_SIZE 256
#define MT_MCU_RING_SIZE 32
#define MT_RX_BUF_SIZE 2048
+#define MT_SKB_HEAD_LEN 128

struct mt76_dev;
struct mt76_wcid;
diff --git a/drivers/net/wireless/mediatek/mt76/usb.c b/drivers/net/wireless/mediatek/mt76/usb.c
index bbaa1365bbda2..dd90427b2d672 100644
--- a/drivers/net/wireless/mediatek/mt76/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/usb.c
@@ -429,6 +429,42 @@ static int mt76u_get_rx_entry_len(u8 *data, u32 data_len)
return dma_len;
}

+static struct sk_buff *
+mt76u_build_rx_skb(void *data, int len, int buf_size)
+{
+ struct sk_buff *skb;
+
+ if (SKB_WITH_OVERHEAD(buf_size) < MT_DMA_HDR_LEN + len) {
+ struct page *page;
+
+ /* slow path, not enough space for data and
+ * skb_shared_info
+ */
+ skb = alloc_skb(MT_SKB_HEAD_LEN, GFP_ATOMIC);
+ if (!skb)
+ return NULL;
+
+ skb_put_data(skb, data + MT_DMA_HDR_LEN, MT_SKB_HEAD_LEN);
+ data += (MT_DMA_HDR_LEN + MT_SKB_HEAD_LEN);
+ page = virt_to_head_page(data);
+ skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+ page, data - page_address(page),
+ len - MT_SKB_HEAD_LEN, buf_size);
+
+ return skb;
+ }
+
+ /* fast path */
+ skb = build_skb(data, buf_size);
+ if (!skb)
+ return NULL;
+
+ skb_reserve(skb, MT_DMA_HDR_LEN);
+ __skb_put(skb, len);
+
+ return skb;
+}
+
static int
mt76u_process_rx_entry(struct mt76_dev *dev, struct urb *urb)
{
@@ -446,19 +482,11 @@ mt76u_process_rx_entry(struct mt76_dev *dev, struct urb *urb)
return 0;

data_len = min_t(int, len, data_len - MT_DMA_HDR_LEN);
- if (MT_DMA_HDR_LEN + data_len > SKB_WITH_OVERHEAD(q->buf_size)) {
- dev_err_ratelimited(dev->dev, "rx data too big %d\n", data_len);
- return 0;
- }
-
- skb = build_skb(data, q->buf_size);
+ skb = mt76u_build_rx_skb(data, data_len, q->buf_size);
if (!skb)
return 0;

- skb_reserve(skb, MT_DMA_HDR_LEN);
- __skb_put(skb, data_len);
len -= data_len;
-
while (len > 0 && nsgs < urb->num_sgs) {
data_len = min_t(int, len, urb->sg[nsgs].length);
skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
--
2.20.1


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