From: Ronald Wahl <ronald.wahl@xxxxxxxxxxx>
When SMP is enabled and spinlocks are actually functional then there is
a deadlock with the 'statelock' spinlock between ks8851_start_xmit_spi
and ks8851_irq:
watchdog: BUG: soft lockup - CPU#0 stuck for 27s!
call trace:
queued_spin_lock_slowpath+0x100/0x284
do_raw_spin_lock+0x34/0x44
ks8851_start_xmit_spi+0x30/0xb8
ks8851_start_xmit+0x14/0x20
netdev_start_xmit+0x40/0x6c
dev_hard_start_xmit+0x6c/0xbc
sch_direct_xmit+0xa4/0x22c
__qdisc_run+0x138/0x3fc
qdisc_run+0x24/0x3c
net_tx_action+0xf8/0x130
handle_softirqs+0x1ac/0x1f0
__do_softirq+0x14/0x20
____do_softirq+0x10/0x1c
call_on_irq_stack+0x3c/0x58
do_softirq_own_stack+0x1c/0x28
__irq_exit_rcu+0x54/0x9c
irq_exit_rcu+0x10/0x1c
el1_interrupt+0x38/0x50
el1h_64_irq_handler+0x18/0x24
el1h_64_irq+0x64/0x68
__netif_schedule+0x6c/0x80
netif_tx_wake_queue+0x38/0x48
ks8851_irq+0xb8/0x2c8
irq_thread_fn+0x2c/0x74
irq_thread+0x10c/0x1b0
kthread+0xc8/0xd8
ret_from_fork+0x10/0x20
This issue has not been identified earlier because tests were done on
a device with SMP disabled and so spinlocks were actually NOPs.
Now use spin_(un)lock_bh for TX queue related locking to avoid execution
of softirq work synchronously that would lead to a deadlock.
Fixes: 3dc5d4454545 ("net: ks8851: Fix TX stall caused by TX buffer overrun")
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Simon Horman <horms@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # 5.10+
Signed-off-by: Ronald Wahl <ronald.wahl@xxxxxxxxxxx>
---
V2: - use spin_lock_bh instead of moving netif_wake_queue outside of
locked region (doing the same in the start_xmit function)
- add missing net: tag
V3: - spin_lock_bh(ks->statelock) always except in xmit which is in BH
already
drivers/net/ethernet/micrel/ks8851_common.c | 8 ++++----
drivers/net/ethernet/micrel/ks8851_spi.c | 4 ++--
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/micrel/ks8851_common.c b/drivers/net/ethernet/micrel/ks8851_common.c
index 6453c92f0fa7..13462811eaae 100644
--- a/drivers/net/ethernet/micrel/ks8851_common.c
+++ b/drivers/net/ethernet/micrel/ks8851_common.c
@@ -352,11 +352,11 @@ static irqreturn_t ks8851_irq(int irq, void *_ks)
netif_dbg(ks, intr, ks->netdev,
"%s: txspace %d\n", __func__, tx_space);
- spin_lock(&ks->statelock);
+ spin_lock_bh(&ks->statelock);
ks->tx_space = tx_space;
if (netif_queue_stopped(ks->netdev))
netif_wake_queue(ks->netdev);
- spin_unlock(&ks->statelock);
+ spin_unlock_bh(&ks->statelock);
}
if (status & IRQ_SPIBEI) {
@@ -635,14 +635,14 @@ static void ks8851_set_rx_mode(struct net_device *dev)
/* schedule work to do the actual set of the data if needed */
- spin_lock(&ks->statelock);
+ spin_lock_bh(&ks->statelock);
if (memcmp(&rxctrl, &ks->rxctrl, sizeof(rxctrl)) != 0) {
memcpy(&ks->rxctrl, &rxctrl, sizeof(ks->rxctrl));
schedule_work(&ks->rxctrl_work);
}
- spin_unlock(&ks->statelock);
+ spin_unlock_bh(&ks->statelock);
}
static int ks8851_set_mac_address(struct net_device *dev, void *addr)
diff --git a/drivers/net/ethernet/micrel/ks8851_spi.c b/drivers/net/ethernet/micrel/ks8851_spi.c
index 670c1de966db..3062cc0f9199 100644
--- a/drivers/net/ethernet/micrel/ks8851_spi.c
+++ b/drivers/net/ethernet/micrel/ks8851_spi.c
@@ -340,10 +340,10 @@ static void ks8851_tx_work(struct work_struct *work)
tx_space = ks8851_rdreg16_spi(ks, KS_TXMIR);
- spin_lock(&ks->statelock);
+ spin_lock_bh(&ks->statelock);
ks->queued_len -= dequeued_len;
ks->tx_space = tx_space;
- spin_unlock(&ks->statelock);
+ spin_unlock_bh(&ks->statelock);
ks8851_unlock_spi(ks, &flags);
}
--
2.45.2
