[PATCH 6.6 055/121] net: ks8851: Fix deadlock with the SPI chip variant

[PATCH 6.6 055/121] net: ks8851: Fix deadlock with the SPI chip variant

[Greg Kroah-Hartman]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ronald Wahl <ronald.wahl@raritan.com>

commit 0913ec336a6c0c4a2b296bd9f74f8e41c4c83c8c upstream.

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@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Ronald Wahl <ronald.wahl@raritan.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20240706101337.854474-1-rwahl@gmx.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/micrel/ks8851_common.c |    8 ++++----
 drivers/net/ethernet/micrel/ks8851_spi.c    |    4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

--- 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, v
 		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 ne
 
 	/* 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)
--- 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_s
 
 	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);
 }

[PATCH 6.6 056/121] net: ks8851: Fix potential TX stall after interface reopen

[Greg Kroah-Hartman]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ronald Wahl <ronald.wahl@raritan.com>

commit 7a99afef17af66c276c1d6e6f4dbcac223eaf6ac upstream.

The amount of TX space in the hardware buffer is tracked in the tx_space
variable. The initial value is currently only set during driver probing.

After closing the interface and reopening it the tx_space variable has
the last value it had before close. If it is smaller than the size of
the first send packet after reopeing the interface the queue will be
stopped. The queue is woken up after receiving a TX interrupt but this
will never happen since we did not send anything.

This commit moves the initialization of the tx_space variable to the
ks8851_net_open function right before starting the TX queue. Also query
the value from the hardware instead of using a hard coded value.

Only the SPI chip variant is affected by this issue because only this
driver variant actually depends on the tx_space variable in the xmit
function.

Fixes: 3dc5d4454545 ("net: ks8851: Fix TX stall caused by TX buffer overrun")
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Ronald Wahl <ronald.wahl@raritan.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20240709195845.9089-1-rwahl@gmx.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/micrel/ks8851_common.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/micrel/ks8851_common.c
+++ b/drivers/net/ethernet/micrel/ks8851_common.c
@@ -482,6 +482,7 @@ static int ks8851_net_open(struct net_de
 	ks8851_wrreg16(ks, KS_IER, ks->rc_ier);
 
 	ks->queued_len = 0;
+	ks->tx_space = ks8851_rdreg16(ks, KS_TXMIR);
 	netif_start_queue(ks->netdev);
 
 	netif_dbg(ks, ifup, ks->netdev, "network device up\n");
@@ -1101,7 +1102,6 @@ int ks8851_probe_common(struct net_devic
 	int ret;
 
 	ks->netdev = netdev;
-	ks->tx_space = 6144;
 
 	ks->gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
 	ret = PTR_ERR_OR_ZERO(ks->gpio);