wil6210: prevent device memory access while in reset or suspend

Accessing some of the memory of the device while the device is
resetting or suspending may cause unexpected error as the HW is still
not in a stable state. Prevent this access to guarantee successful
read/write memory operations.

Signed-off-by: Ahmad Masri <amasri@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

1 files changed, 31 insertions, 10 deletions

diff --git a/drivers/net/wireless/ath/wil6210/main.c b/drivers/net/wireless/ath/wil6210/main.c
index 277abfdf3322..6df19a2a6ce7 100644
--- a/drivers/net/wireless/ath/wil6210/main.c
+++ b/drivers/net/wireless/ath/wil6210/main.c
@@ -184,6 +184,28 @@ void wil_memcpy_toio_32(volatile void __iomem *dst, const void *src,
 	}
 }
 
+/* Device memory access is prohibited while reset or suspend.
+ * wil_mem_access_lock protects accessing device memory in these cases
+ */
+int wil_mem_access_lock(struct wil6210_priv *wil)
+{
+	if (!down_read_trylock(&wil->mem_lock))
+		return -EBUSY;
+
+	if (test_bit(wil_status_suspending, wil->status) ||
+	    test_bit(wil_status_suspended, wil->status)) {
+		up_read(&wil->mem_lock);
+		return -EBUSY;
+	}
+
+	return 0;
+}
+
+void wil_mem_access_unlock(struct wil6210_priv *wil)
+{
+	up_read(&wil->mem_lock);
+}
+
 static void wil_ring_fini_tx(struct wil6210_priv *wil, int id)
 {
 	struct wil_ring *ring = &wil->ring_tx[id];
@@ -703,6 +725,7 @@ int wil_priv_init(struct wil6210_priv *wil)
 	spin_lock_init(&wil->wmi_ev_lock);
 	spin_lock_init(&wil->net_queue_lock);
 	init_waitqueue_head(&wil->wq);
+	init_rwsem(&wil->mem_lock);
 
 	wil->wmi_wq = create_singlethread_workqueue(WIL_NAME "_wmi");
 	if (!wil->wmi_wq)
@@ -1599,15 +1622,6 @@ int wil_reset(struct wil6210_priv *wil, bool load_fw)
 	}
 
 	set_bit(wil_status_resetting, wil->status);
-	if (test_bit(wil_status_collecting_dumps, wil->status)) {
-		/* Device collects crash dump, cancel the reset.
-		 * following crash dump collection, reset would take place.
-		 */
-		wil_dbg_misc(wil, "reject reset while collecting crash dump\n");
-		rc = -EBUSY;
-		goto out;
-	}
-
 	mutex_lock(&wil->vif_mutex);
 	wil_abort_scan_all_vifs(wil, false);
 	mutex_unlock(&wil->vif_mutex);
@@ -1782,7 +1796,9 @@ int __wil_up(struct wil6210_priv *wil)
 
 	WARN_ON(!mutex_is_locked(&wil->mutex));
 
+	down_write(&wil->mem_lock);
 	rc = wil_reset(wil, true);
+	up_write(&wil->mem_lock);
 	if (rc)
 		return rc;
 
@@ -1854,6 +1870,7 @@ int wil_up(struct wil6210_priv *wil)
 
 int __wil_down(struct wil6210_priv *wil)
 {
+	int rc;
 	WARN_ON(!mutex_is_locked(&wil->mutex));
 
 	set_bit(wil_status_resetting, wil->status);
@@ -1873,7 +1890,11 @@ int __wil_down(struct wil6210_priv *wil)
 	wil_abort_scan_all_vifs(wil, false);
 	mutex_unlock(&wil->vif_mutex);
 
-	return wil_reset(wil, false);
+	down_write(&wil->mem_lock);
+	rc = wil_reset(wil, false);
+	up_write(&wil->mem_lock);
+
+	return rc;
 }
 
 int wil_down(struct wil6210_priv *wil)