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* [PATCH AUTOSEL 4.19 219/252] ath10k: pci: Only dump ATH10K_MEM_REGION_TYPE_IOREG when safe
From: Sasha Levin @ 2020-02-14 16:11 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Bryan O'Donoghue, Kalle Valo, Sasha Levin, ath10k,
	linux-wireless, netdev
In-Reply-To: <20200214161147.15842-1-sashal@kernel.org>

From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>

[ 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 <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 2a503aacf0c64..caece8339a50a 100644
--- a/drivers/net/wireless/ath/ath10k/pci.c
+++ b/drivers/net/wireless/ath/ath10k/pci.c
@@ -1613,11 +1613,22 @@ 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 */
@@ -1713,7 +1724,11 @@ 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


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