netdev - [PATCH net-next] iavf: check that state transitions happen under lock

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Date:   Fri, 28 Oct 2022 15:45:15 +0200
From:   Stefan Assmann <sassmann@...nic.de>
To:     intel-wired-lan@...ts.osuosl.org
Cc:     netdev@...r.kernel.org, anthony.l.nguyen@...el.com,
        patryk.piotrowski@...el.com, sassmann@...nic.de
Subject: [PATCH net-next] iavf: check that state transitions happen under lock

Add a check to make sure crit_lock is being held during every state
transition and print a warning if that's not the case. For convenience
a wrapper is added that helps pointing out where the locking is missing.

Make an exception for iavf_probe() as that is too early in the init
process and generates a false positive report.

Signed-off-by: Stefan Assmann <sassmann@...nic.de>
---
 drivers/net/ethernet/intel/iavf/iavf.h      | 23 +++++++++++++++------
 drivers/net/ethernet/intel/iavf/iavf_main.c |  2 +-
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf.h b/drivers/net/ethernet/intel/iavf/iavf.h
index 3f6187c16424..28f41bbc9c86 100644
--- a/drivers/net/ethernet/intel/iavf/iavf.h
+++ b/drivers/net/ethernet/intel/iavf/iavf.h
@@ -498,19 +498,30 @@ static inline const char *iavf_state_str(enum iavf_state_t state)
 	}
 }
 
-static inline void iavf_change_state(struct iavf_adapter *adapter,
-				     enum iavf_state_t state)
+static inline void __iavf_change_state(struct iavf_adapter *adapter,
+				       enum iavf_state_t state,
+				       const char *func,
+				       int line)
 {
 	if (adapter->state != state) {
 		adapter->last_state = adapter->state;
 		adapter->state = state;
 	}
-	dev_dbg(&adapter->pdev->dev,
-		"state transition from:%s to:%s\n",
-		iavf_state_str(adapter->last_state),
-		iavf_state_str(adapter->state));
+	if (mutex_is_locked(&adapter->crit_lock))
+		dev_dbg(&adapter->pdev->dev, "%s:%d state transition %s to %s\n",
+			func, line,
+			iavf_state_str(adapter->last_state),
+			iavf_state_str(adapter->state));
+	else
+		dev_warn(&adapter->pdev->dev, "%s:%d state transition %s to %s without locking!\n",
+			 func, line,
+			 iavf_state_str(adapter->last_state),
+			 iavf_state_str(adapter->state));
 }
 
+#define iavf_change_state(adapter, state) \
+	__iavf_change_state(adapter, state, __func__, __LINE__)
+
 int iavf_up(struct iavf_adapter *adapter);
 void iavf_down(struct iavf_adapter *adapter);
 int iavf_process_config(struct iavf_adapter *adapter);
diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index 3fc572341781..bbc0c9f347a7 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_main.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
@@ -4892,7 +4892,7 @@ static int iavf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	hw->back = adapter;
 
 	adapter->msg_enable = BIT(DEFAULT_DEBUG_LEVEL_SHIFT) - 1;
-	iavf_change_state(adapter, __IAVF_STARTUP);
+	adapter->state = __IAVF_STARTUP;
 
 	/* Call save state here because it relies on the adapter struct. */
 	pci_save_state(pdev);
-- 
2.37.3