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FAILED: patch "[PATCH] net: stmmac: Prevent NULL deref when RX memory exhausted" failed to apply to 6.12-stable tree

PATCH New [email protected] 2 participants 4 messages May 4 – May 10

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Network drivers Stable branch Arm STM32 stmmac Ethernet driver
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author maintainer
#0 lore raw

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 0bb05e6adfa99a2ea1fee1125cc0953409f83ed8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026050448-gawk-hybrid-73b9@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0bb05e6adfa99a2ea1fee1125cc0953409f83ed8 Mon Sep 17 00:00:00 2001
From: Sam Edwards <[email protected]>
Date: Tue, 21 Apr 2026 21:45:03 -0700
Subject: [PATCH] net: stmmac: Prevent NULL deref when RX memory exhausted

The CPU receives frames from the MAC through conventional DMA: the CPU allocates buffers for the MAC, then the MAC fills them and returns ownership to the CPU. For each hardware RX queue, the CPU and MAC coordinate through a shared ring array of DMA descriptors: one descriptor per DMA buffer. Each descriptor includes the buffer's physical address and a status flag ("OWN") indicating which side owns the buffer: OWN=0 for CPU, OWN=1 for MAC. The CPU is only allowed to set the flag and the MAC is only allowed to clear it, and both must move through the ring in sequence: thus the ring is used for both "submissions" and "completions."

In the stmmac driver, stmmac_rx() bookmarks its position in the ring with the cur_rx index. The main receive loop in that function checks for rx_descs[cur_rx].own=0, gives the corresponding buffer to the network stack (NULLing the pointer), and increments cur_rx modulo the ring size. After the loop exits, stmmac_rx_refill(), which bookmarks its position with dirty_rx, allocates fresh buffers and rearms the descriptors (setting OWN=1). If it fails any allocation, it simply stops early (leaving OWN=0) and will retry where it left off when next called.

This means descriptors have a three-stage lifecycle (terms my own):
- empty (OWN=1, buffer valid)
- full (OWN=0, buffer valid and populated)
- dirty (OWN=0, buffer NULL)

But because stmmac_rx() only checks OWN, it confuses full/dirty. In the past (see 'Fixes:'), there was a bug where the loop could cycle cur_rx all the way back to the first descriptor it dirtied, resulting in a NULL dereference when mistaken for full. The aforementioned commit resolved that *specific* failure by capping the loop's iteration limit at dma_rx_size - 1, but this is only a partial fix: if the previous stmmac_rx_refill() didn't complete, then there are leftover dirty descriptors that the loop might encounter without needing to cycle fully around. The current code therefore panics (see 'Closes:') when stmmac_rx_refill() is memory-starved long enough for cur_rx to catch up to dirty_rx.

Fix this by explicitly checking, before advancing cur_rx, if the next entry is dirty; exit the loop if so. This prevents processing of the final, used descriptor until stmmac_rx_refill() succeeds, but fully prevents the cur_rx == dirty_rx ambiguity as the previous bugfix
intended: so remove the clamp as well. Since stmmac_rx_zc() is a copy-paste-and-tweak of stmmac_rx() and the code structure is identical, any fix to stmmac_rx() will also need a corresponding fix for stmmac_rx_zc(). Therefore, apply the same check there.

In stmmac_rx() (not stmmac_rx_zc()), a related bug remains: after the MAC sets OWN=0 on the final descriptor, it will be unable to send any further DMA-complete IRQs until it's given more empty descriptors. Currently, the driver simply *hopes* that the next stmmac_rx_refill() succeeds, risking an indefinite stall of the receive process if not. But this is not a regression, so it can be addressed in a future change.

Fixes b6cb4541853c7 ("net: stmmac: avoid rx queue overrun")
Closes https://bugzilla.kernel.org/show_bug.cgi?id=221010
Cc [email protected]
Suggested-by Russell King <[email protected]>
Signed-off-by Sam Edwards <[email protected]>
Link https://patch.msgid.link/[email protected] open here
Signed-off-by Paolo Abeni <[email protected]>
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +12 -7
index ca68248dbc78..3591755ea30b 100644
@@ -5549,9 +5549,12 @@ static int stmmac_rx_zc(struct stmmac_priv *priv, int limit, u32 queue)
 			break;
 
 		/* Prefetch the next RX descriptor */
-		rx_q->cur_rx = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
-						priv->dma_conf.dma_rx_size);
-		next_entry = rx_q->cur_rx;
+		next_entry = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
+					       priv->dma_conf.dma_rx_size);
+		if (unlikely(next_entry == rx_q->dirty_rx))
+			break;
+
+		rx_q->cur_rx = next_entry;
 
 		np = stmmac_get_rx_desc(priv, rx_q, next_entry);
 

@@ -5686,7 +5689,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 
 	dma_dir = page_pool_get_dma_dir(rx_q->page_pool);
 	bufsz = DIV_ROUND_UP(priv->dma_conf.dma_buf_sz, PAGE_SIZE) * PAGE_SIZE;
-	limit = min(priv->dma_conf.dma_rx_size - 1, (unsigned int)limit);
 
 	if (netif_msg_rx_status(priv)) {
 		void *rx_head = stmmac_get_rx_desc(priv, rx_q, 0);

@@ -5733,9 +5735,12 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 		if (unlikely(status & dma_own))
 			break;
 
-		rx_q->cur_rx = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
-						priv->dma_conf.dma_rx_size);
-		next_entry = rx_q->cur_rx;
+		next_entry = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
+					       priv->dma_conf.dma_rx_size);
+		if (unlikely(next_entry == rx_q->dirty_rx))
+			break;
+
+		rx_q->cur_rx = next_entry;
 
 		np = stmmac_get_rx_desc(priv, rx_q, next_entry);
maintainer
#1 lore raw

PATCH 1/3 net: stmmac: avoid shadowing global buf_sz

From: "Russell King (Oracle)" <[email protected]>

[ Upstream commit 876cfb20e8892143c0c967b3657074f9131f9b5f ]

stmmac_rx() declares a local variable named "buf_sz" but there is also a global variable for a module parameter which is called the same. To avoid confusion, rename the local variable.

Signed-off-by Russell King (Oracle) <[email protected]>
Reviewed-by Furong Xu <[email protected]>
Link https://patch.msgid.link/[email protected] open here
Signed-off-by Jakub Kicinski <[email protected]>

Stable-dep-of: 0bb05e6adfa9 ("net: stmmac: Prevent NULL deref when RX memory exhausted")

Signed-off-by Sasha Levin <[email protected]>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +3 -3
index 5016b8c39b684..8d32d4fc67735 100644
@@ -5406,10 +5406,10 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 	struct sk_buff *skb = NULL;
 	struct stmmac_xdp_buff ctx;
 	int xdp_status = 0;
-	int buf_sz;
+	int bufsz;
 
 	dma_dir = page_pool_get_dma_dir(rx_q->page_pool);
-	buf_sz = DIV_ROUND_UP(priv->dma_conf.dma_buf_sz, PAGE_SIZE) * PAGE_SIZE;
+	bufsz = DIV_ROUND_UP(priv->dma_conf.dma_buf_sz, PAGE_SIZE) * PAGE_SIZE;
 	limit = min(priv->dma_conf.dma_rx_size - 1, (unsigned int)limit);
 
 	if (netif_msg_rx_status(priv)) {

@@ -5524,7 +5524,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 			dma_sync_single_for_cpu(priv->device, buf->addr,
 						buf1_len, dma_dir);
 
-			xdp_init_buff(&ctx.xdp, buf_sz, &rx_q->xdp_rxq);
+			xdp_init_buff(&ctx.xdp, bufsz, &rx_q->xdp_rxq);
 			xdp_prepare_buff(&ctx.xdp, page_address(buf->page),
 					 buf->page_offset, buf1_len, true);
Signature · 1 line
2.53.0
maintainer
#2 lore raw

PATCH 2/3 net: stmmac: rename STMMAC_GET_ENTRY() -> STMMAC_NEXT_ENTRY()

From: "Russell King (Oracle)" <[email protected]>

[ Upstream commit 6b4286e0550814cdc4b897f881ec1fa8b0313227 ]

STMMAC_GET_ENTRY() doesn't describe what this macro is doing - it is incrementing the provided index for the circular array of descriptors. Replace "GET" with "NEXT" as this better describes the action here.

Signed-off-by Russell King (Oracle) <[email protected]>
Link https://patch.msgid.link/[email protected] open here
Signed-off-by Jakub Kicinski <[email protected]>

Stable-dep-of: 0bb05e6adfa9 ("net: stmmac: Prevent NULL deref when RX memory exhausted")

Signed-off-by Sasha Levin <[email protected]>
---
 .../net/ethernet/stmicro/stmmac/chain_mode.c  |  2 +-
 drivers/net/ethernet/stmicro/stmmac/common.h  |  2 +-
 .../net/ethernet/stmicro/stmmac/ring_mode.c   |  2 +-
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 26 +++++++++----------
 4 files changed, 16 insertions(+), 16 deletions(-)
drivers/net/ethernet/stmicro/stmmac/chain_mode.c +1 -1
index 1c01e3c640cee..2515608878235 100644
@@ -47,7 +47,7 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
 
 	while (len != 0) {
 		tx_q->tx_skbuff[entry] = NULL;
-		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
+		entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_tx_size);
 		desc = tx_q->dma_tx + entry;
 
 		if (len > bmax) {
drivers/net/ethernet/stmicro/stmmac/common.h +1 -1
index 7d47c002eaf0a..03786c7f2b1fc 100644
@@ -55,7 +55,7 @@
 #define DMA_MIN_RX_SIZE		64
 #define DMA_MAX_RX_SIZE		1024
 #define DMA_DEFAULT_RX_SIZE	512
-#define STMMAC_GET_ENTRY(x, size)	((x + 1) & (size - 1))
+#define STMMAC_NEXT_ENTRY(x, size)	((x + 1) & (size - 1))
 
 #undef FRAME_FILTER_DEBUG
 /* #define FRAME_FILTER_DEBUG */
drivers/net/ethernet/stmicro/stmmac/ring_mode.c +1 -1
index d218412ca832f..45c14c1bb0eaa 100644
@@ -51,7 +51,7 @@ static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
 		stmmac_prepare_tx_desc(priv, desc, 1, bmax, csum,
 				STMMAC_RING_MODE, 0, false, skb->len);
 		tx_q->tx_skbuff[entry] = NULL;
-		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
+		entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_tx_size);
 
 		if (priv->extend_desc)
 			desc = (struct dma_desc *)(tx_q->dma_etx + entry);
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +13 -13
index 8d32d4fc67735..1fd3977ec01ab 100644
@@ -2583,7 +2583,7 @@ static bool stmmac_xdp_xmit_zc(struct stmmac_priv *priv, u32 queue, u32 budget)
 		xsk_tx_metadata_to_compl(meta,
 					 &tx_q->tx_skbuff_dma[entry].xsk_meta);
 
-		tx_q->cur_tx = STMMAC_GET_ENTRY(tx_q->cur_tx, priv->dma_conf.dma_tx_size);
+		tx_q->cur_tx = STMMAC_NEXT_ENTRY(tx_q->cur_tx, priv->dma_conf.dma_tx_size);
 		entry = tx_q->cur_tx;
 	}
 	u64_stats_update_begin(&txq_stats->napi_syncp);

@@ -2754,7 +2754,7 @@ static int stmmac_tx_clean(struct stmmac_priv *priv, int budget, u32 queue,
 
 		stmmac_release_tx_desc(priv, p, priv->mode);
 
-		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
+		entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_tx_size);
 	}
 	tx_q->dirty_tx = entry;
 

@@ -4076,7 +4076,7 @@ static bool stmmac_vlan_insert(struct stmmac_priv *priv, struct sk_buff *skb,
 		return false;
 
 	stmmac_set_tx_owner(priv, p);
-	tx_q->cur_tx = STMMAC_GET_ENTRY(tx_q->cur_tx, priv->dma_conf.dma_tx_size);
+	tx_q->cur_tx = STMMAC_NEXT_ENTRY(tx_q->cur_tx, priv->dma_conf.dma_tx_size);
 	return true;
 }
 

@@ -4104,7 +4104,7 @@ static void stmmac_tso_allocator(struct stmmac_priv *priv, dma_addr_t des,
 	while (tmp_len > 0) {
 		dma_addr_t curr_addr;
 
-		tx_q->cur_tx = STMMAC_GET_ENTRY(tx_q->cur_tx,
+		tx_q->cur_tx = STMMAC_NEXT_ENTRY(tx_q->cur_tx,
 						priv->dma_conf.dma_tx_size);
 		WARN_ON(tx_q->tx_skbuff[tx_q->cur_tx]);
 

@@ -4250,7 +4250,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 
 		stmmac_set_mss(priv, mss_desc, mss);
 		tx_q->mss = mss;
-		tx_q->cur_tx = STMMAC_GET_ENTRY(tx_q->cur_tx,
+		tx_q->cur_tx = STMMAC_NEXT_ENTRY(tx_q->cur_tx,
 						priv->dma_conf.dma_tx_size);
 		WARN_ON(tx_q->tx_skbuff[tx_q->cur_tx]);
 	}

@@ -4369,7 +4369,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * ndo_start_xmit will fill this descriptor the next time it's
 	 * called and stmmac_tx_clean may clean up to this descriptor.
 	 */
-	tx_q->cur_tx = STMMAC_GET_ENTRY(tx_q->cur_tx, priv->dma_conf.dma_tx_size);
+	tx_q->cur_tx = STMMAC_NEXT_ENTRY(tx_q->cur_tx, priv->dma_conf.dma_tx_size);
 
 	if (unlikely(stmmac_tx_avail(priv, queue) <= (MAX_SKB_FRAGS + 1))) {
 		netif_dbg(priv, hw, priv->dev, "%s: stop transmitted packets\n",

@@ -4568,7 +4568,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 		int len = skb_frag_size(frag);
 		bool last_segment = (i == (nfrags - 1));
 
-		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
+		entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_tx_size);
 		WARN_ON(tx_q->tx_skbuff[entry]);
 
 		if (likely(priv->extend_desc))

@@ -4638,7 +4638,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * ndo_start_xmit will fill this descriptor the next time it's
 	 * called and stmmac_tx_clean may clean up to this descriptor.
 	 */
-	entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
+	entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_tx_size);
 	tx_q->cur_tx = entry;
 
 	if (netif_msg_pktdata(priv)) {

@@ -4807,7 +4807,7 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv, u32 queue)
 		dma_wmb();
 		stmmac_set_rx_owner(priv, p, use_rx_wd);
 
-		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_rx_size);
+		entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_rx_size);
 	}
 	rx_q->dirty_rx = entry;
 	rx_q->rx_tail_addr = rx_q->dma_rx_phy +

@@ -4941,7 +4941,7 @@ static int stmmac_xdp_xmit_xdpf(struct stmmac_priv *priv, int queue,
 
 	stmmac_enable_dma_transmission(priv, priv->ioaddr, queue);
 
-	entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
+	entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_tx_size);
 	tx_q->cur_tx = entry;
 
 	return STMMAC_XDP_TX;

@@ -5175,7 +5175,7 @@ static bool stmmac_rx_refill_zc(struct stmmac_priv *priv, u32 queue, u32 budget)
 		dma_wmb();
 		stmmac_set_rx_owner(priv, rx_desc, use_rx_wd);
 
-		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_rx_size);
+		entry = STMMAC_NEXT_ENTRY(entry, priv->dma_conf.dma_rx_size);
 	}
 
 	if (rx_desc) {

@@ -5270,7 +5270,7 @@ static int stmmac_rx_zc(struct stmmac_priv *priv, int limit, u32 queue)
 			break;
 
 		/* Prefetch the next RX descriptor */
-		rx_q->cur_rx = STMMAC_GET_ENTRY(rx_q->cur_rx,
+		rx_q->cur_rx = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
 						priv->dma_conf.dma_rx_size);
 		next_entry = rx_q->cur_rx;
 

@@ -5466,7 +5466,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 		if (unlikely(status & dma_own))
 			break;
 
-		rx_q->cur_rx = STMMAC_GET_ENTRY(rx_q->cur_rx,
+		rx_q->cur_rx = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
 						priv->dma_conf.dma_rx_size);
 		next_entry = rx_q->cur_rx;
Signature · 1 line
2.53.0
maintainer
#3 lore raw

PATCH 3/3 net: stmmac: Prevent NULL deref when RX memory exhausted

In reply to Sasha Levin

From: Sam Edwards <[email protected]>

[ Upstream commit 0bb05e6adfa99a2ea1fee1125cc0953409f83ed8 ]

The CPU receives frames from the MAC through conventional DMA: the CPU allocates buffers for the MAC, then the MAC fills them and returns ownership to the CPU. For each hardware RX queue, the CPU and MAC coordinate through a shared ring array of DMA descriptors: one descriptor per DMA buffer. Each descriptor includes the buffer's physical address and a status flag ("OWN") indicating which side owns the buffer: OWN=0 for CPU, OWN=1 for MAC. The CPU is only allowed to set the flag and the MAC is only allowed to clear it, and both must move through the ring in sequence: thus the ring is used for both "submissions" and "completions."

In the stmmac driver, stmmac_rx() bookmarks its position in the ring with the cur_rx index. The main receive loop in that function checks for rx_descs[cur_rx].own=0, gives the corresponding buffer to the network stack (NULLing the pointer), and increments cur_rx modulo the ring size. After the loop exits, stmmac_rx_refill(), which bookmarks its position with dirty_rx, allocates fresh buffers and rearms the descriptors (setting OWN=1). If it fails any allocation, it simply stops early (leaving OWN=0) and will retry where it left off when next called.

This means descriptors have a three-stage lifecycle (terms my own):
- empty (OWN=1, buffer valid)
- full (OWN=0, buffer valid and populated)
- dirty (OWN=0, buffer NULL)

But because stmmac_rx() only checks OWN, it confuses full/dirty. In the past (see 'Fixes:'), there was a bug where the loop could cycle cur_rx all the way back to the first descriptor it dirtied, resulting in a NULL dereference when mistaken for full. The aforementioned commit resolved that *specific* failure by capping the loop's iteration limit at dma_rx_size - 1, but this is only a partial fix: if the previous stmmac_rx_refill() didn't complete, then there are leftover dirty descriptors that the loop might encounter without needing to cycle fully around. The current code therefore panics (see 'Closes:') when stmmac_rx_refill() is memory-starved long enough for cur_rx to catch up to dirty_rx.

Fix this by explicitly checking, before advancing cur_rx, if the next entry is dirty; exit the loop if so. This prevents processing of the final, used descriptor until stmmac_rx_refill() succeeds, but fully prevents the cur_rx == dirty_rx ambiguity as the previous bugfix
intended: so remove the clamp as well. Since stmmac_rx_zc() is a copy-paste-and-tweak of stmmac_rx() and the code structure is identical, any fix to stmmac_rx() will also need a corresponding fix for stmmac_rx_zc(). Therefore, apply the same check there.

In stmmac_rx() (not stmmac_rx_zc()), a related bug remains: after the MAC sets OWN=0 on the final descriptor, it will be unable to send any further DMA-complete IRQs until it's given more empty descriptors. Currently, the driver simply *hopes* that the next stmmac_rx_refill() succeeds, risking an indefinite stall of the receive process if not. But this is not a regression, so it can be addressed in a future change.

Fixes b6cb4541853c7 ("net: stmmac: avoid rx queue overrun")
Closes https://bugzilla.kernel.org/show_bug.cgi?id=221010
Cc [email protected]
Suggested-by Russell King <[email protected]>
Signed-off-by Sam Edwards <[email protected]>
Link https://patch.msgid.link/[email protected] open here
Signed-off-by Paolo Abeni <[email protected]>
Signed-off-by Sasha Levin <[email protected]>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +12 -7
index 1fd3977ec01ab..893746b2a4961 100644
@@ -5270,9 +5270,12 @@ static int stmmac_rx_zc(struct stmmac_priv *priv, int limit, u32 queue)
 			break;
 
 		/* Prefetch the next RX descriptor */
-		rx_q->cur_rx = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
-						priv->dma_conf.dma_rx_size);
-		next_entry = rx_q->cur_rx;
+		next_entry = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
+					       priv->dma_conf.dma_rx_size);
+		if (unlikely(next_entry == rx_q->dirty_rx))
+			break;
+
+		rx_q->cur_rx = next_entry;
 
 		if (priv->extend_desc)
 			np = (struct dma_desc *)(rx_q->dma_erx + next_entry);

@@ -5410,7 +5413,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 
 	dma_dir = page_pool_get_dma_dir(rx_q->page_pool);
 	bufsz = DIV_ROUND_UP(priv->dma_conf.dma_buf_sz, PAGE_SIZE) * PAGE_SIZE;
-	limit = min(priv->dma_conf.dma_rx_size - 1, (unsigned int)limit);
 
 	if (netif_msg_rx_status(priv)) {
 		void *rx_head;

@@ -5466,9 +5468,12 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 		if (unlikely(status & dma_own))
 			break;
 
-		rx_q->cur_rx = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
-						priv->dma_conf.dma_rx_size);
-		next_entry = rx_q->cur_rx;
+		next_entry = STMMAC_NEXT_ENTRY(rx_q->cur_rx,
+					       priv->dma_conf.dma_rx_size);
+		if (unlikely(next_entry == rx_q->dirty_rx))
+			break;
+
+		rx_q->cur_rx = next_entry;
 
 		if (priv->extend_desc)
 			np = (struct dma_desc *)(rx_q->dma_erx + next_entry);
Signature · 1 line
2.53.0