[PATCH net] net: ti: icssg-prueth: Add lock to stats

[MD Danish Anwar]

Currently the API emac_update_hardware_stats() reads different ICSSG
stats without any lock protection.

This API gets called by .ndo_get_stats64() which is only under RCU
protection and nothing else. Add lock to this API so that the reading of
statistics happens during lock.

Fixes: c1e10d5dc7a1 ("net: ti: icssg-prueth: Add ICSSG Stats")
Signed-off-by: MD Danish Anwar <danishanwar@xxxxxx>
---
NOTE: This was suggested by Jakub Kicinski <kuba@xxxxxxxxxx> [1] to get
this as bug fix in net during upstreaming of FW Stats for ICSSG driver
This patch doesn't depend on [1] and can be applied cleanly on net/main

[1] https://lore.kernel.org/all/20250306165513.541ff46e@xxxxxxxxxx/

 drivers/net/ethernet/ti/icssg/icssg_prueth.c | 1 +
 drivers/net/ethernet/ti/icssg/icssg_prueth.h | 2 ++
 drivers/net/ethernet/ti/icssg/icssg_stats.c  | 4 ++++
 3 files changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
index 00ed97860547..9a75733e3f8f 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
@@ -1679,6 +1679,7 @@ static int prueth_probe(struct platform_device *pdev)
 	}
 
 	spin_lock_init(&prueth->vtbl_lock);
+	spin_lock_init(&prueth->stats_lock);
 	/* setup netdev interfaces */
 	if (eth0_node) {
 		ret = prueth_netdev_init(prueth, eth0_node);
diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.h b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
index 329b46e9ee53..f41786b05741 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.h
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
@@ -305,6 +305,8 @@ struct prueth {
 	int default_vlan;
 	/** @vtbl_lock: Lock for vtbl in shared memory */
 	spinlock_t vtbl_lock;
+	/** @stats_lock: Lock for reading icssg stats */
+	spinlock_t stats_lock;
 };
 
 struct emac_tx_ts_response {
diff --git a/drivers/net/ethernet/ti/icssg/icssg_stats.c b/drivers/net/ethernet/ti/icssg/icssg_stats.c
index 8800bd3a8d07..6f0edae38ea2 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_stats.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_stats.c
@@ -26,6 +26,8 @@ void emac_update_hardware_stats(struct prueth_emac *emac)
 	u32 val, reg;
 	int i;
 
+	spin_lock(&prueth->stats_lock);
+
 	for (i = 0; i < ARRAY_SIZE(icssg_all_miig_stats); i++) {
 		regmap_read(prueth->miig_rt,
 			    base + icssg_all_miig_stats[i].offset,
@@ -51,6 +53,8 @@ void emac_update_hardware_stats(struct prueth_emac *emac)
 			emac->pa_stats[i] += val;
 		}
 	}
+
+	spin_unlock(&prueth->stats_lock);
 }
 
 void icssg_stats_work_handler(struct work_struct *work)

base-commit: 4003c9e78778e93188a09d6043a74f7154449d43
-- 
2.34.1