[RFC net v4 4/4] bnxt_en: refuse to open a device with stopped DMA

[Joe Damato <joe@dama.to>]

Add BNXT_STATE_DMA_STOPPED and set it in bnxt_stop_dma() to signal that
the device had DMA disabled. When opening the device later, check this
bit and exit with an error.

This is a very rare case, but when it happens the device needs manual
intervention by the user to become usable again.

Fixes: 74608fc98d28 ("bnxt_en: Ring free response from close path should use completion ring")
Signed-off-by: Joe Damato <joe@dama.to>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 26 ++++++++++++++++++++---
 drivers/net/ethernet/broadcom/bnxt/bnxt.h |  1 +
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 33e9ce8eb449..21da989e136e 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -7814,9 +7814,20 @@ static void bnxt_stop_dma(struct bnxt *bp)
 {
 	netdev_err(bp->dev,
 		   "Disabling DMA before releasing ring memory, the driver must be rebound to recover\n");
+	set_bit(BNXT_STATE_DMA_STOPPED, &bp->state);
 	pci_clear_master(bp->pdev);
 }
 
+static int bnxt_check_dma_stopped(struct bnxt *bp)
+{
+	if (!test_bit(BNXT_STATE_DMA_STOPPED, &bp->state))
+		return 0;
+
+	netdev_err(bp->dev,
+		   "DMA was disabled after the firmware failed to free rings, rebind the driver to recover\n");
+	return -ENODEV;
+}
+
 static int __bnxt_trim_rings(struct bnxt *bp, int *rx, int *tx, int max,
 			     bool shared);
 static int bnxt_trim_rings(struct bnxt *bp, int *rx, int *tx, int max,
@@ -13387,9 +13398,10 @@ static int __bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 
 int bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 {
-	int rc = 0;
+	int rc;
 
-	if (test_bit(BNXT_STATE_ABORT_ERR, &bp->state))
+	rc = bnxt_check_dma_stopped(bp);
+	if (!rc && test_bit(BNXT_STATE_ABORT_ERR, &bp->state))
 		rc = -EIO;
 	if (!rc)
 		rc = __bnxt_open_nic(bp, irq_re_init, link_re_init);
@@ -13406,7 +13418,11 @@ int bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
  */
 int bnxt_half_open_nic(struct bnxt *bp)
 {
-	int rc = 0;
+	int rc;
+
+	rc = bnxt_check_dma_stopped(bp);
+	if (rc)
+		goto half_open_err;
 
 	if (test_bit(BNXT_STATE_ABORT_ERR, &bp->state)) {
 		netdev_err(bp->dev, "A previous firmware reset has not completed, aborting half open\n");
@@ -13466,6 +13482,10 @@ static int bnxt_open(struct net_device *dev)
 	struct bnxt *bp = netdev_priv(dev);
 	int rc;
 
+	rc = bnxt_check_dma_stopped(bp);
+	if (rc)
+		return rc;
+
 	if (test_bit(BNXT_STATE_ABORT_ERR, &bp->state)) {
 		rc = bnxt_reinit_after_abort(bp);
 		if (rc) {
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index c673b2ce4a0d..061f57824c7a 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -2470,6 +2470,7 @@ struct bnxt {
 #define BNXT_STATE_DRV_REGISTERED	7
 #define BNXT_STATE_PCI_CHANNEL_IO_FROZEN	8
 #define BNXT_STATE_NAPI_DISABLED	9
+#define BNXT_STATE_DMA_STOPPED		10
 #define BNXT_STATE_FW_ACTIVATE		11
 #define BNXT_STATE_RECOVER		12
 #define BNXT_STATE_FW_NON_FATAL_COND	13
-- 
2.53.0-Meta