linux-kernel - [PATCH 3/7] habanalabs: fix nullifying of destroyed mmu pgt pool

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Date:   Sun, 11 Jul 2021 15:54:14 +0300
From:   Oded Gabbay <ogabbay@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Tomer Tayar <ttayar@...ana.ai>
Subject: [PATCH 3/7] habanalabs: fix nullifying of destroyed mmu pgt pool

From: Tomer Tayar <ttayar@...ana.ai>

In case of host-resident MMU, when the page tables pool is destroyed,
its pointer is not nullified correctly.
As a result, on a device fini which happens after a failing reset, the
already destroyed pool is accessed, which leads to a kernel panic.
The patch fixes the setting of the pool pointer to NULL.

Signed-off-by: Tomer Tayar <ttayar@...ana.ai>
Reviewed-by: Oded Gabbay <ogabbay@...nel.org>
Signed-off-by: Oded Gabbay <ogabbay@...nel.org>
---
 drivers/misc/habanalabs/common/mmu/mmu_v1.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/misc/habanalabs/common/mmu/mmu_v1.c b/drivers/misc/habanalabs/common/mmu/mmu_v1.c
index c5e93ff32586..0f536f79dd9c 100644
--- a/drivers/misc/habanalabs/common/mmu/mmu_v1.c
+++ b/drivers/misc/habanalabs/common/mmu/mmu_v1.c
@@ -470,13 +470,13 @@ static void hl_mmu_v1_fini(struct hl_device *hdev)
 	if (!ZERO_OR_NULL_PTR(hdev->mmu_priv.hr.mmu_shadow_hop0)) {
 		kvfree(hdev->mmu_priv.dr.mmu_shadow_hop0);
 		gen_pool_destroy(hdev->mmu_priv.dr.mmu_pgt_pool);
-	}
 
-	/* Make sure that if we arrive here again without init was called we
-	 * won't cause kernel panic. This can happen for example if we fail
-	 * during hard reset code at certain points
-	 */
-	hdev->mmu_priv.dr.mmu_shadow_hop0 = NULL;
+		/* Make sure that if we arrive here again without init was
+		 * called we won't cause kernel panic. This can happen for
+		 * example if we fail during hard reset code at certain points
+		 */
+		hdev->mmu_priv.dr.mmu_shadow_hop0 = NULL;
+	}
 }
 
 /**
-- 
2.25.1