Subject: [PATCH AUTOSEL 5.5 471/542] ath10k: pci: Only dump ATH10K_MEM_REGION_TYPE_IOREG when safe

From: Sasha Levin <[email-masked]>
Date: Fri, 14 Feb 2020 10:47:43 -0500

From: Bryan O'Donoghue <[email-masked]>

[ Upstream commit d239380196c4e27a26fa4bea73d2bf994c14ec2d ]

ath10k_pci_dump_memory_reg() will try to access memory of type
ATH10K_MEM_REGION_TYPE_IOREG however, if a hardware restart is in progress
this can crash a system.

Individual ioread32() time has been observed to jump from 15-20 ticks to >
80k ticks followed by a secure-watchdog bite and a system reset.

Work around this corner case by only issuing the read transaction when the
driver state is ATH10K_STATE_ON.

Tested-on: QCA9988 PCI 10.4-3.9.0.2-00044

Fixes: 219cc084c6706 ("ath10k: add memory dump support QCA9984")
Signed-off-by: Bryan O'Donoghue <[email-masked]>
Signed-off-by: Kalle Valo <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 drivers/net/wireless/ath/ath10k/pci.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c
index bb44f5a0941b9..4822a65f6f3c2 100644
--- a/drivers/net/wireless/ath/ath10k/pci.c
+++ b/drivers/net/wireless/ath/ath10k/pci.c
@@ -1604,11 +1604,22 @@ static int ath10k_pci_dump_memory_reg(struct ath10k *ar,
 {
 	struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
 	u32 i;
+	int ret;
+
+	mutex_lock(&ar->conf_mutex);
+	if (ar->state != ATH10K_STATE_ON) {
+		ath10k_warn(ar, "Skipping pci_dump_memory_reg invalid state\n");
+		ret = -EIO;
+		goto done;
+	}
 
 	for (i = 0; i < region->len; i += 4)
 		*(u32 *)(buf + i) = ioread32(ar_pci->mem + region->start + i);
 
-	return region->len;
+	ret = region->len;
+done:
+	mutex_unlock(&ar->conf_mutex);
+	return ret;
 }
 
 /* if an error happened returns < 0, otherwise the length */
@@ -1704,7 +1715,11 @@ static void ath10k_pci_dump_memory(struct ath10k *ar,
 			count = ath10k_pci_dump_memory_sram(ar, current_region, buf);
 			break;
 		case ATH10K_MEM_REGION_TYPE_IOREG:
-			count = ath10k_pci_dump_memory_reg(ar, current_region, buf);
+			ret = ath10k_pci_dump_memory_reg(ar, current_region, buf);
+			if (ret < 0)
+				break;
+
+			count = ret;
 			break;
 		default:
 			ret = ath10k_pci_dump_memory_generic(ar, current_region, buf);
-- 
2.20.1