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.
This commit moves the netif_wake_queue call outside the spinlock
protected area.
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>
---
drivers/net/ethernet/micrel/ks8851_common.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/micrel/ks8851_common.c b/drivers/net/ethernet/micrel/ks8851_common.c
index 6453c92f0fa7..60b959126b26 100644
--- a/drivers/net/ethernet/micrel/ks8851_common.c
+++ b/drivers/net/ethernet/micrel/ks8851_common.c
@@ -348,15 +348,17 @@ static irqreturn_t ks8851_irq(int irq, void *_ks)
if (status & IRQ_TXI) {
unsigned short tx_space = ks8851_rdreg16(ks, KS_TXMIR);
+ bool need_wake_queue;
netif_dbg(ks, intr, ks->netdev,
"%s: txspace %d\n", __func__, tx_space);
spin_lock(&ks->statelock);
ks->tx_space = tx_space;
- if (netif_queue_stopped(ks->netdev))
- netif_wake_queue(ks->netdev);
+ need_wake_queue = netif_queue_stopped(ks->netdev);
spin_unlock(&ks->statelock);
+ if (need_wake_queue)
+ netif_wake_queue(ks->netdev);
}
if (status & IRQ_SPIBEI) {
--
2.45.2
