[PATCH net v3 6/9] ibmvnic: track pending login

[Dany Madden <drt@linux.ibm.com>]

From: Sukadev Bhattiprolu <sukadev@linux.ibm.com>

If after ibmvnic sends a LOGIN it gets a FAILOVER, it is possible that
the worker thread will start reset process and free the login response
buffer before it gets a (now stale) LOGIN_RSP. The ibmvnic tasklet will
then try to access the login response buffer and crash.

Have ibmvnic track pending logins and discard any stale login responses.

Fixes: 032c5e82847a ("Driver for IBM System i/p VNIC protocol")
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 17 +++++++++++++++++
 drivers/net/ethernet/ibm/ibmvnic.h |  1 +
 2 files changed, 18 insertions(+)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index e2f9b0e9dea8..55b07bd4c741 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -3839,6 +3839,8 @@ static int send_login(struct ibmvnic_adapter *adapter)
 	crq.login.cmd = LOGIN;
 	crq.login.ioba = cpu_to_be32(buffer_token);
 	crq.login.len = cpu_to_be32(buffer_size);
+
+	adapter->login_pending = true;
 	ibmvnic_send_crq(adapter, &crq);
 
 	return 0;
@@ -4391,6 +4393,15 @@ static int handle_login_rsp(union ibmvnic_crq *login_rsp_crq,
 	u64 *size_array;
 	int i;
 
+	/* CHECK: Test/set of login_pending does not need to be atomic
+	 * because only ibmvnic_tasklet tests/clears this.
+	 */
+	if (!adapter->login_pending) {
+		netdev_warn(netdev, "Ignoring unexpected login response\n");
+		return 0;
+	}
+	adapter->login_pending = false;
+
 	dma_unmap_single(dev, adapter->login_buf_token, adapter->login_buf_sz,
 			 DMA_TO_DEVICE);
 	dma_unmap_single(dev, adapter->login_rsp_buf_token,
@@ -4762,6 +4773,11 @@ static void ibmvnic_handle_crq(union ibmvnic_crq *crq,
 		case IBMVNIC_CRQ_INIT:
 			dev_info(dev, "Partner initialized\n");
 			adapter->from_passive_init = true;
+			/* Discard any stale login responses from prev reset.
+			 * CHECK: should we clear even on INIT_COMPLETE?
+			 */
+			adapter->login_pending = false;
+
 			if (!completion_done(&adapter->init_done)) {
 				complete(&adapter->init_done);
 				adapter->init_done_rc = -EIO;
@@ -5191,6 +5207,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 	dev_set_drvdata(&dev->dev, netdev);
 	adapter->vdev = dev;
 	adapter->netdev = netdev;
+	adapter->login_pending = false;
 
 	ether_addr_copy(adapter->mac_addr, mac_addr_p);
 	ether_addr_copy(netdev->dev_addr, adapter->mac_addr);
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h
index 217dcc7ded70..6f0a701c4a38 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -1087,6 +1087,7 @@ struct ibmvnic_adapter {
 	struct delayed_work ibmvnic_delayed_reset;
 	unsigned long resetting;
 	bool napi_enabled, from_passive_init;
+	bool login_pending;
 
 	bool failover_pending;
 	bool force_reset_recovery;
-- 
2.26.2