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From a19f5011670341975abb182247038c378baf4234 Mon Sep 17 00:00:00 2001
From: Christian Koenig <christian.koenig@amd.com>
Date: Mon, 11 Sep 2017 18:24:37 -0400
Subject: [PATCH 0920/4131] drm/amdgpu: keep the MMU lock until the update ends
v4
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
This is quite controversial because it adds another lock which is held during
page table updates, but I don't see much other option.
v2: allow multiple updates to be in flight at the same time
v3: simplify the patch, take the read side only once
v4: correctly fix rebase conflict
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Kalyan Alle <kalyan.alle@amd.com>
Conflicts:
drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
Change-Id: I932e17b4e1564a3974004b501b26e00d8259782a
---
drivers/gpu/drm/amd/amdgpu/amdgpu.h | 4 +--
drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c | 55 +++++++++++++++++++++++++++++++++-
2 files changed, 56 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 3c7a9bf..547fc1a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1221,11 +1221,11 @@ void amdgpu_test_moves(struct amdgpu_device *adev);
* MMU Notifier
*/
#if defined(CONFIG_MMU_NOTIFIER)
+void amdgpu_mn_lock(struct amdgpu_mn *mn);
+void amdgpu_mn_unlock(struct amdgpu_mn *mn);
struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev);
int amdgpu_mn_register(struct amdgpu_bo *bo, unsigned long addr);
void amdgpu_mn_unregister(struct amdgpu_bo *bo);
-void amdgpu_mn_lock(struct amdgpu_mn *mn);
-void amdgpu_mn_unlock(struct amdgpu_mn *mn);
#else
static inline void amdgpu_mn_lock(struct amdgpu_mn *mn) {}
static inline void amdgpu_mn_unlock(struct amdgpu_mn *mn) {}
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
index da6ffaa..89d45aa 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
@@ -52,6 +52,8 @@ struct amdgpu_mn {
/* objects protected by lock */
struct rw_semaphore lock;
struct rb_root_cached objects;
+ struct mutex read_lock;
+ atomic_t recursion;
};
struct amdgpu_mn_node {
@@ -126,6 +128,34 @@ void amdgpu_mn_unlock(struct amdgpu_mn *mn)
}
/**
+ * amdgpu_mn_read_lock - take the rmn read lock
+ *
+ * @rmn: our notifier
+ *
+ * Take the rmn read side lock.
+ */
+static void amdgpu_mn_read_lock(struct amdgpu_mn *rmn)
+{
+ mutex_lock(&rmn->read_lock);
+ if (atomic_inc_return(&rmn->recursion) == 1)
+ down_read_non_owner(&rmn->lock);
+ mutex_unlock(&rmn->read_lock);
+}
+
+/**
+ * amdgpu_mn_read_unlock - drop the rmn read lock
+ *
+ * @rmn: our notifier
+ *
+ * Drop the rmn read side lock.
+ */
+static void amdgpu_mn_read_unlock(struct amdgpu_mn *rmn)
+{
+ if (atomic_dec_return(&rmn->recursion) == 0)
+ up_read_non_owner(&rmn->lock);
+}
+
+/**
* amdgpu_mn_invalidate_node - unmap all BOs of a node
*
* @node: the node with the BOs to unmap
@@ -176,7 +206,7 @@ static void amdgpu_mn_invalidate_range_start(struct mmu_notifier *mn,
/* notification is exclusive, but interval is inclusive */
end -= 1;
- down_read(&rmn->lock);
+ amdgpu_mn_read_lock(rmn);
it = interval_tree_iter_first(&rmn->objects, start, end);
while (it) {
@@ -191,9 +221,30 @@ static void amdgpu_mn_invalidate_range_start(struct mmu_notifier *mn,
up_read(&rmn->lock);
}
+/**
+ * amdgpu_mn_invalidate_range_end - callback to notify about mm change
+ *
+ * @mn: our notifier
+ * @mn: the mm this callback is about
+ * @start: start of updated range
+ * @end: end of updated range
+ *
+ * Release the lock again to allow new command submissions.
+ */
+static void amdgpu_mn_invalidate_range_end(struct mmu_notifier *mn,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ struct amdgpu_mn *rmn = container_of(mn, struct amdgpu_mn, mn);
+
+ amdgpu_mn_read_unlock(rmn);
+}
+
static const struct mmu_notifier_ops amdgpu_mn_ops = {
.release = amdgpu_mn_release,
.invalidate_range_start = amdgpu_mn_invalidate_range_start,
+ .invalidate_range_end = amdgpu_mn_invalidate_range_end,
};
/**
@@ -231,6 +282,8 @@ struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev,
rmn->mn.ops = &amdgpu_mn_ops;
init_rwsem(&rmn->lock);
rmn->objects = RB_ROOT_CACHED;
+ mutex_init(&rmn->read_lock);
+ atomic_set(&rmn->recursion, 0);
r = __mmu_notifier_register(&rmn->mn, mm);
if (r)
--
2.7.4
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