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Message-ID: <20251105074955.1766792-1-horatiu.vultur@microchip.com>
Date: Wed, 5 Nov 2025 08:49:55 +0100
From: Horatiu Vultur <horatiu.vultur@...rochip.com>
To: <UNGLinuxDriver@...rochip.com>, <andrew+netdev@...n.ch>,
<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
<pabeni@...hat.com>
CC: <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Horatiu Vultur
<horatiu.vultur@...rochip.com>
Subject: [PATCH net] lan966x: Fix sleeping in atomic context
The following warning was seen when we try to connect using ssh to the device.
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:575
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 104, name: dropbear
preempt_count: 1, expected: 0
INFO: lockdep is turned off.
CPU: 0 UID: 0 PID: 104 Comm: dropbear Tainted: G W 6.18.0-rc2-00399-g6f1ab1b109b9-dirty #530 NONE
Tainted: [W]=WARN
Hardware name: Generic DT based system
Call trace:
unwind_backtrace from show_stack+0x10/0x14
show_stack from dump_stack_lvl+0x7c/0xac
dump_stack_lvl from __might_resched+0x16c/0x2b0
__might_resched from __mutex_lock+0x64/0xd34
__mutex_lock from mutex_lock_nested+0x1c/0x24
mutex_lock_nested from lan966x_stats_get+0x5c/0x558
lan966x_stats_get from dev_get_stats+0x40/0x43c
dev_get_stats from dev_seq_printf_stats+0x3c/0x184
dev_seq_printf_stats from dev_seq_show+0x10/0x30
dev_seq_show from seq_read_iter+0x350/0x4ec
seq_read_iter from seq_read+0xfc/0x194
seq_read from proc_reg_read+0xac/0x100
proc_reg_read from vfs_read+0xb0/0x2b0
vfs_read from ksys_read+0x6c/0xec
ksys_read from ret_fast_syscall+0x0/0x1c
Exception stack(0xf0b11fa8 to 0xf0b11ff0)
1fa0: 00000001 00001000 00000008 be9048d8 00001000 00000001
1fc0: 00000001 00001000 00000008 00000003 be905920 0000001e 00000000 00000001
1fe0: 0005404c be9048c0 00018684 b6ec2cd8
It seems that we are using a mutex in a atomic context which is wrong.
Change the mutex with a spinlock.
Fixes: 12c2d0a5b8e2 ("net: lan966x: add ethtool configuration and statistics")
Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
---
.../microchip/lan966x/lan966x_ethtool.c | 18 +++++++++---------
.../ethernet/microchip/lan966x/lan966x_main.c | 2 --
.../ethernet/microchip/lan966x/lan966x_main.h | 4 ++--
.../microchip/lan966x/lan966x_vcap_impl.c | 8 ++++----
4 files changed, 15 insertions(+), 17 deletions(-)
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_ethtool.c b/drivers/net/ethernet/microchip/lan966x/lan966x_ethtool.c
index 2474dfd330f46..fe4e614052840 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_ethtool.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_ethtool.c
@@ -294,7 +294,7 @@ static void lan966x_stats_update(struct lan966x *lan966x)
{
int i, j;
- mutex_lock(&lan966x->stats_lock);
+ spin_lock(&lan966x->stats_lock);
for (i = 0; i < lan966x->num_phys_ports; i++) {
uint idx = i * lan966x->num_stats;
@@ -310,7 +310,7 @@ static void lan966x_stats_update(struct lan966x *lan966x)
}
}
- mutex_unlock(&lan966x->stats_lock);
+ spin_unlock(&lan966x->stats_lock);
}
static int lan966x_get_sset_count(struct net_device *dev, int sset)
@@ -365,7 +365,7 @@ static void lan966x_get_eth_mac_stats(struct net_device *dev,
idx = port->chip_port * lan966x->num_stats;
- mutex_lock(&lan966x->stats_lock);
+ spin_lock(&lan966x->stats_lock);
mac_stats->FramesTransmittedOK =
lan966x->stats[idx + SYS_COUNT_TX_UC] +
@@ -416,7 +416,7 @@ static void lan966x_get_eth_mac_stats(struct net_device *dev,
lan966x->stats[idx + SYS_COUNT_RX_LONG] +
lan966x->stats[idx + SYS_COUNT_RX_PMAC_LONG];
- mutex_unlock(&lan966x->stats_lock);
+ spin_unlock(&lan966x->stats_lock);
}
static const struct ethtool_rmon_hist_range lan966x_rmon_ranges[] = {
@@ -442,7 +442,7 @@ static void lan966x_get_eth_rmon_stats(struct net_device *dev,
idx = port->chip_port * lan966x->num_stats;
- mutex_lock(&lan966x->stats_lock);
+ spin_lock(&lan966x->stats_lock);
rmon_stats->undersize_pkts =
lan966x->stats[idx + SYS_COUNT_RX_SHORT] +
@@ -500,7 +500,7 @@ static void lan966x_get_eth_rmon_stats(struct net_device *dev,
lan966x->stats[idx + SYS_COUNT_TX_SZ_1024_1526] +
lan966x->stats[idx + SYS_COUNT_TX_PMAC_SZ_1024_1526];
- mutex_unlock(&lan966x->stats_lock);
+ spin_unlock(&lan966x->stats_lock);
*ranges = lan966x_rmon_ranges;
}
@@ -603,7 +603,7 @@ void lan966x_stats_get(struct net_device *dev,
idx = port->chip_port * lan966x->num_stats;
- mutex_lock(&lan966x->stats_lock);
+ spin_lock(&lan966x->stats_lock);
stats->rx_bytes = lan966x->stats[idx + SYS_COUNT_RX_OCT] +
lan966x->stats[idx + SYS_COUNT_RX_PMAC_OCT];
@@ -685,7 +685,7 @@ void lan966x_stats_get(struct net_device *dev,
stats->collisions = lan966x->stats[idx + SYS_COUNT_TX_COL];
- mutex_unlock(&lan966x->stats_lock);
+ spin_unlock(&lan966x->stats_lock);
}
int lan966x_stats_init(struct lan966x *lan966x)
@@ -701,7 +701,7 @@ int lan966x_stats_init(struct lan966x *lan966x)
return -ENOMEM;
/* Init stats worker */
- mutex_init(&lan966x->stats_lock);
+ spin_lock_init(&lan966x->stats_lock);
snprintf(queue_name, sizeof(queue_name), "%s-stats",
dev_name(lan966x->dev));
lan966x->stats_queue = create_singlethread_workqueue(queue_name);
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index 7001584f1b7a6..47752d3fde0b1 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
@@ -1261,7 +1261,6 @@ static int lan966x_probe(struct platform_device *pdev)
cancel_delayed_work_sync(&lan966x->stats_work);
destroy_workqueue(lan966x->stats_queue);
- mutex_destroy(&lan966x->stats_lock);
debugfs_remove_recursive(lan966x->debugfs_root);
@@ -1279,7 +1278,6 @@ static void lan966x_remove(struct platform_device *pdev)
cancel_delayed_work_sync(&lan966x->stats_work);
destroy_workqueue(lan966x->stats_queue);
- mutex_destroy(&lan966x->stats_lock);
lan966x_mac_purge_entries(lan966x);
lan966x_mdb_deinit(lan966x);
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
index 4f75f06883693..eea286c29474f 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
@@ -295,8 +295,8 @@ struct lan966x {
const struct lan966x_stat_layout *stats_layout;
u32 num_stats;
- /* workqueue for reading stats */
- struct mutex stats_lock;
+ /* lock for reading stats */
+ spinlock_t stats_lock;
u64 *stats;
struct delayed_work stats_work;
struct workqueue_struct *stats_queue;
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_vcap_impl.c b/drivers/net/ethernet/microchip/lan966x/lan966x_vcap_impl.c
index a1471e38d1189..2a37fc1ba4bcd 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_vcap_impl.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_vcap_impl.c
@@ -403,11 +403,11 @@ static void lan966x_es0_read_esdx_counter(struct lan966x *lan966x,
u32 counter;
id = id & 0xff; /* counter limit */
- mutex_lock(&lan966x->stats_lock);
+ spin_lock(&lan966x->stats_lock);
lan_wr(SYS_STAT_CFG_STAT_VIEW_SET(id), lan966x, SYS_STAT_CFG);
counter = lan_rd(lan966x, SYS_CNT(LAN966X_STAT_ESDX_GRN_PKTS)) +
lan_rd(lan966x, SYS_CNT(LAN966X_STAT_ESDX_YEL_PKTS));
- mutex_unlock(&lan966x->stats_lock);
+ spin_unlock(&lan966x->stats_lock);
if (counter)
admin->cache.counter = counter;
}
@@ -417,14 +417,14 @@ static void lan966x_es0_write_esdx_counter(struct lan966x *lan966x,
{
id = id & 0xff; /* counter limit */
- mutex_lock(&lan966x->stats_lock);
+ spin_lock(&lan966x->stats_lock);
lan_wr(SYS_STAT_CFG_STAT_VIEW_SET(id), lan966x, SYS_STAT_CFG);
lan_wr(0, lan966x, SYS_CNT(LAN966X_STAT_ESDX_GRN_BYTES));
lan_wr(admin->cache.counter, lan966x,
SYS_CNT(LAN966X_STAT_ESDX_GRN_PKTS));
lan_wr(0, lan966x, SYS_CNT(LAN966X_STAT_ESDX_YEL_BYTES));
lan_wr(0, lan966x, SYS_CNT(LAN966X_STAT_ESDX_YEL_PKTS));
- mutex_unlock(&lan966x->stats_lock);
+ spin_unlock(&lan966x->stats_lock);
}
static void lan966x_vcap_cache_write(struct net_device *dev,
--
2.34.1
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