[PATCH net v1 0/4] Fix race conditions in ndo_get_stats64

[PATCH net v1 0/4] Fix race conditions in ndo_get_stats64

[Shinas Rasheed]

Fix race conditions in ndo_get_stats64 by implementing a state variable
check, and remove unnecessary firmware stats fetch which is currently
unnecessary

Shinas Rasheed (4):
  octeon_ep: fix race conditions in ndo_get_stats64
  octeon_ep: remove firmware stats fetch in ndo_get_stats64
  octeon_ep_vf: fix race conditions in ndo_get_stats64
  octeon_ep_vf: remove firmware stats fetch in ndo_get_stats64

 .../ethernet/marvell/octeon_ep/octep_main.c   | 34 ++++++++++++-----
 .../ethernet/marvell/octeon_ep/octep_main.h   |  8 ++++
 .../marvell/octeon_ep_vf/octep_vf_main.c      | 37 +++++++++++++++----
 .../marvell/octeon_ep_vf/octep_vf_main.h      |  9 +++++
 4 files changed, 71 insertions(+), 17 deletions(-)

-- 
2.25.1

[PATCH net v1 1/4] octeon_ep: fix race conditions in ndo_get_stats64

[Shinas Rasheed]

ndo_get_stats64() can race with ndo_stop(), which frees input and
output queue resources. Implement device state variable to protect
against such resource usage.

Fixes: 6a610a46bad1 ("octeon_ep: add support for ndo ops")
Signed-off-by: Shinas Rasheed <srasheed@marvell.com>
---
 .../ethernet/marvell/octeon_ep/octep_main.c   | 27 +++++++++++++++++++
 .../ethernet/marvell/octeon_ep/octep_main.h   |  8 ++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
index 549436efc204..872b4848027c 100644
--- a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
+++ b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
@@ -733,6 +733,7 @@ static int octep_open(struct net_device *netdev)
 	if (ret > 0)
 		octep_link_up(netdev);
 
+	set_bit(OCTEP_DEV_STATE_OPEN, &oct->state);
 	return 0;
 
 set_queues_err:
@@ -745,6 +746,11 @@ static int octep_open(struct net_device *netdev)
 	return -1;
 }
 
+static bool octep_drv_busy(struct octep_device *oct)
+{
+	return test_bit(OCTEP_DEV_STATE_READ_STATS, &oct->state);
+}
+
 /**
  * octep_stop() - stop the octeon network device.
  *
@@ -759,6 +765,14 @@ static int octep_stop(struct net_device *netdev)
 
 	netdev_info(netdev, "Stopping the device ...\n");
 
+	clear_bit(OCTEP_DEV_STATE_OPEN, &oct->state);
+	/* Make sure device state open is cleared so that no more
+	 * stats fetch can happen intermittently
+	 */
+	smp_mb__after_atomic();
+	while (octep_drv_busy(oct))
+		msleep(20);
+
 	octep_ctrl_net_set_link_status(oct, OCTEP_CTRL_NET_INVALID_VFID, false,
 				       false);
 	octep_ctrl_net_set_rx_state(oct, OCTEP_CTRL_NET_INVALID_VFID, false,
@@ -1001,6 +1015,16 @@ static void octep_get_stats64(struct net_device *netdev,
 					    &oct->iface_rx_stats,
 					    &oct->iface_tx_stats);
 
+	set_bit(OCTEP_DEV_STATE_READ_STATS, &oct->state);
+	/* Make sure read stats state is set, so that ndo_stop
+	 * doesn't clear resources as they are read
+	 */
+	smp_mb__after_atomic();
+	if (!test_bit(OCTEP_DEV_STATE_OPEN, &oct->state)) {
+		clear_bit(OCTEP_DEV_STATE_READ_STATS, &oct->state);
+		return;
+	}
+
 	tx_packets = 0;
 	tx_bytes = 0;
 	rx_packets = 0;
@@ -1022,6 +1046,7 @@ static void octep_get_stats64(struct net_device *netdev,
 	stats->rx_errors = oct->iface_rx_stats.err_pkts;
 	stats->collisions = oct->iface_tx_stats.xscol;
 	stats->tx_fifo_errors = oct->iface_tx_stats.undflw;
+	clear_bit(OCTEP_DEV_STATE_READ_STATS, &oct->state);
 }
 
 /**
@@ -1526,6 +1551,8 @@ static int octep_sriov_disable(struct octep_device *oct)
 	pci_disable_sriov(pdev);
 	CFG_GET_ACTIVE_VFS(oct->conf) = 0;
 
+	clear_bit(OCTEP_DEV_STATE_OPEN, &oct->state);
+
 	return 0;
 }
 
diff --git a/drivers/net/ethernet/marvell/octeon_ep/octep_main.h b/drivers/net/ethernet/marvell/octeon_ep/octep_main.h
index fee59e0e0138..78293366e7de 100644
--- a/drivers/net/ethernet/marvell/octeon_ep/octep_main.h
+++ b/drivers/net/ethernet/marvell/octeon_ep/octep_main.h
@@ -223,6 +223,12 @@ struct octep_pfvf_info {
 	u32 mbox_version;
 };
 
+/* Device state */
+enum octep_dev_state {
+	OCTEP_DEV_STATE_OPEN,
+	OCTEP_DEV_STATE_READ_STATS,
+};
+
 /* The Octeon device specific private data structure.
  * Each Octeon device has this structure to represent all its components.
  */
@@ -318,6 +324,8 @@ struct octep_device {
 	atomic_t hb_miss_cnt;
 	/* Task to reset device on heartbeat miss */
 	struct delayed_work hb_task;
+	/* Device state */
+	unsigned long state;
 };
 
 static inline u16 OCTEP_MAJOR_REV(struct octep_device *oct)
-- 
2.25.1

[PATCH net v1 2/4] octeon_ep: remove firmware stats fetch in ndo_get_stats64

[Shinas Rasheed]

The per queue stats are available already and are retrieved
from register reads during ndo_get_stats64. The firmware stats
fetch call that happens in ndo_get_stats64() is currently not
required

Fixes: 6a610a46bad1 ("octeon_ep: add support for ndo ops")
Signed-off-by: Shinas Rasheed <srasheed@marvell.com>
---
 drivers/net/ethernet/marvell/octeon_ep/octep_main.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
index 872b4848027c..8c0a955a02dc 100644
--- a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
+++ b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
@@ -1009,12 +1009,6 @@ static void octep_get_stats64(struct net_device *netdev,
 	struct octep_device *oct = netdev_priv(netdev);
 	int q;
 
-	if (netif_running(netdev))
-		octep_ctrl_net_get_if_stats(oct,
-					    OCTEP_CTRL_NET_INVALID_VFID,
-					    &oct->iface_rx_stats,
-					    &oct->iface_tx_stats);
-
 	set_bit(OCTEP_DEV_STATE_READ_STATS, &oct->state);
 	/* Make sure read stats state is set, so that ndo_stop
 	 * doesn't clear resources as they are read
@@ -1042,11 +1036,6 @@ static void octep_get_stats64(struct net_device *netdev,
 	stats->tx_bytes = tx_bytes;
 	stats->rx_packets = rx_packets;
 	stats->rx_bytes = rx_bytes;
-	stats->multicast = oct->iface_rx_stats.mcast_pkts;
-	stats->rx_errors = oct->iface_rx_stats.err_pkts;
-	stats->collisions = oct->iface_tx_stats.xscol;
-	stats->tx_fifo_errors = oct->iface_tx_stats.undflw;
-	clear_bit(OCTEP_DEV_STATE_READ_STATS, &oct->state);
 }
 
 /**
-- 
2.25.1

[PATCH net v1 3/4] octeon_ep_vf: fix race conditions in ndo_get_stats64

[Shinas Rasheed]

ndo_get_stats64() can race with ndo_stop(), which frees input and
output queue resources. Implement device state variable to protect
against such resource usage.

Fixes: c3fad23cdc06 ("octeon_ep_vf: add support for ndo ops")
Signed-off-by: Shinas Rasheed <srasheed@marvell.com>
---
 .../marvell/octeon_ep_vf/octep_vf_main.c      | 29 +++++++++++++++++++
 .../marvell/octeon_ep_vf/octep_vf_main.h      |  9 ++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c
index 7e6771c9cdbb..12b95fb21e64 100644
--- a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c
+++ b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c
@@ -497,6 +497,8 @@ static int octep_vf_open(struct net_device *netdev)
 	if (ret)
 		octep_vf_link_up(netdev);
 
+	set_bit(OCTEP_VF_DEV_STATE_OPEN, &oct->state);
+
 	return 0;
 
 set_queues_err:
@@ -511,6 +513,11 @@ static int octep_vf_open(struct net_device *netdev)
 	return -1;
 }
 
+static bool octep_vf_drv_busy(struct octep_vf_device *oct)
+{
+	return test_bit(OCTEP_VF_DEV_STATE_READ_STATS, &oct->state);
+}
+
 /**
  * octep_vf_stop() - stop the octeon network device.
  *
@@ -525,6 +532,14 @@ static int octep_vf_stop(struct net_device *netdev)
 
 	netdev_info(netdev, "Stopping the device ...\n");
 
+	clear_bit(OCTEP_VF_DEV_STATE_OPEN, &oct->state);
+	/* Make sure device state open is cleared so that no more
+	 * stats fetch can happen intermittently
+	 */
+	smp_mb__after_atomic();
+	while (octep_vf_drv_busy(oct))
+		msleep(20);
+
 	/* Stop Tx from stack */
 	netif_carrier_off(netdev);
 	netif_tx_disable(netdev);
@@ -782,6 +797,16 @@ static void octep_vf_get_stats64(struct net_device *netdev,
 	u64 tx_packets, tx_bytes, rx_packets, rx_bytes;
 	int q;
 
+	set_bit(OCTEP_VF_DEV_STATE_READ_STATS, &oct->state);
+	/* Make sure read stats state is set, so that ndo_stop
+	 * doesn't clear resources as they are read
+	 */
+	smp_mb__after_atomic();
+	if (!test_bit(OCTEP_VF_DEV_STATE_OPEN, &oct->state)) {
+		clear_bit(OCTEP_VF_DEV_STATE_READ_STATS, &oct->state);
+		return;
+	}
+
 	tx_packets = 0;
 	tx_bytes = 0;
 	rx_packets = 0;
@@ -807,6 +832,7 @@ static void octep_vf_get_stats64(struct net_device *netdev,
 		stats->rx_missed_errors = oct->iface_rx_stats.dropped_pkts_fifo_full;
 		stats->tx_dropped = oct->iface_tx_stats.dropped;
 	}
+	clear_bit(OCTEP_VF_DEV_STATE_READ_STATS, &oct->state);
 }
 
 /**
@@ -1140,6 +1166,9 @@ static int octep_vf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		dev_err(&pdev->dev, "Failed to register netdev\n");
 		goto delete_mbox;
 	}
+
+	clear_bit(OCTEP_VF_DEV_STATE_OPEN, &octep_vf_dev->state);
+
 	dev_info(&pdev->dev, "Device probe successful\n");
 	return 0;
 
diff --git a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.h b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.h
index 5769f62545cd..692b3bf94722 100644
--- a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.h
+++ b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.h
@@ -213,6 +213,12 @@ struct octep_vf_fw_info {
 	u16 tx_ol_flags;
 };
 
+/* Device state */
+enum octep_vf_dev_state {
+	OCTEP_VF_DEV_STATE_OPEN,
+	OCTEP_VF_DEV_STATE_READ_STATS,
+};
+
 /* The Octeon device specific private data structure.
  * Each Octeon device has this structure to represent all its components.
  */
@@ -282,6 +288,9 @@ struct octep_vf_device {
 	/* offset for iface stats */
 	u32 ctrl_mbox_ifstats_offset;
 
+	/* Device state */
+	unsigned long state;
+
 	/* Negotiated Mbox version */
 	u32 mbox_neg_ver;
 
-- 
2.25.1

[PATCH net v1 4/4] octeon_ep_vf: remove firmware stats fetch in ndo_get_stats64

[Shinas Rasheed]

The per queue stats are available already and are retrieved
from register reads during ndo_get_stats64. The firmware stats
fetch call that happens in ndo_get_stats64() is currently not
required

Fixes: c3fad23cdc06 ("octeon_ep_vf: add support for ndo ops")
Signed-off-by: Shinas Rasheed <srasheed@marvell.com>
---
 drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c
index 12b95fb21e64..38e93d79ae59 100644
--- a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c
+++ b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_main.c
@@ -824,14 +824,6 @@ static void octep_vf_get_stats64(struct net_device *netdev,
 	stats->tx_bytes = tx_bytes;
 	stats->rx_packets = rx_packets;
 	stats->rx_bytes = rx_bytes;
-	if (!octep_vf_get_if_stats(oct)) {
-		stats->multicast = oct->iface_rx_stats.mcast_pkts;
-		stats->rx_errors = oct->iface_rx_stats.err_pkts;
-		stats->rx_dropped = oct->iface_rx_stats.dropped_pkts_fifo_full +
-				    oct->iface_rx_stats.err_pkts;
-		stats->rx_missed_errors = oct->iface_rx_stats.dropped_pkts_fifo_full;
-		stats->tx_dropped = oct->iface_tx_stats.dropped;
-	}
 	clear_bit(OCTEP_VF_DEV_STATE_READ_STATS, &oct->state);
 }
 
-- 
2.25.1

Re: [PATCH net v1 1/4] octeon_ep: fix race conditions in ndo_get_stats64

[Jakub Kicinski]

On Mon, 2 Dec 2024 23:21:27 -0800 Shinas Rasheed wrote:
> +	clear_bit(OCTEP_DEV_STATE_OPEN, &oct->state);
> +	/* Make sure device state open is cleared so that no more
> +	 * stats fetch can happen intermittently
> +	 */
> +	smp_mb__after_atomic();
> +	while (octep_drv_busy(oct))
> +		msleep(20);

This is a poor re-implementation of a lock.
We have more lock types in Linux than I care to count now.
Please just use the right one. Hint, it's probably a spin lock or
RCU+synchronize_net() on close.
-- 
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