From 1396500d673bd027683a0609ff84dca7eb6ea2e7 Mon Sep 17 00:00:00 2001
From: Lucas Stach <l.stach@pengutronix.de>
Date: Tue, 21 May 2019 14:53:40 +0200
Subject: drm/etnaviv: lock MMU while dumping core
Git-commit: 1396500d673bd027683a0609ff84dca7eb6ea2e7
Patch-mainline: v5.2-rc3
References: bsc#1113722

The devcoredump needs to operate on a stable state of the MMU while
it is writing the MMU state to the coredump. The missing lock
allowed both the userspace submit, as well as the GPU job finish
paths to mutate the MMU state while a coredump is under way.

Fixes: a8c21a5451d8 (drm/etnaviv: add initial etnaviv DRM driver)
Reported-by: David Jander <david@protonic.nl>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Tested-by: David Jander <david@protonic.nl>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/etnaviv/etnaviv_dump.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/gpu/drm/etnaviv/etnaviv_dump.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_dump.c
@@ -124,6 +124,8 @@ void etnaviv_core_dump(struct etnaviv_gp
 		return;
 	etnaviv_dump_core = false;
 
+	mutex_lock(&gpu->mmu->lock);
+
 	mmu_size = etnaviv_iommu_dump_size(gpu->mmu);
 
 	/* We always dump registers, mmu, ring and end marker */
@@ -166,6 +168,7 @@ void etnaviv_core_dump(struct etnaviv_gp
 	iter.start = __vmalloc(file_size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
 			       PAGE_KERNEL);
 	if (!iter.start) {
+		mutex_unlock(&gpu->mmu->lock);
 		dev_warn(gpu->dev, "failed to allocate devcoredump file\n");
 		return;
 	}
@@ -233,6 +236,8 @@ void etnaviv_core_dump(struct etnaviv_gp
 					 obj->base.size);
 	}
 
+	mutex_unlock(&gpu->mmu->lock);
+
 	etnaviv_core_dump_header(&iter, ETDUMP_BUF_END, iter.data);
 
 	dev_coredumpv(gpu->dev, iter.start, iter.data - iter.start, GFP_KERNEL);