[Intel-gfx] [PATCH] drm/syncobj: Avoid kmalloc(GFP_KERNEL) under spinlock
Chunming Zhou
david1.zhou at amd.com
Thu Oct 25 15:08:31 UTC 2018
drivers/gpu/drm/drm_syncobj.c:202:4-14: ERROR: function drm_syncobj_find_signal_pt_for_point called on line 390 inside lock on line 389 but uses GFP_KERNEL
Find functions that refer to GFP_KERNEL but are called with locks held.
Generated by: scripts/coccinelle/locks/call_kern.cocci
v2:
syncobj->timeline still needs protect.
v3:
use a global signaled fence instead of re-allocation.
v4:
Don't need moving lock.
Don't expose func.
Tested by: syncobj_wait and ./deqp-vk -n dEQP-VK.*semaphore* with
lock debug kernel options enabled.
Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: intel-gfx at lists.freedesktop.org
Cc: Christian König <easy2remember.chk at googlemail.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
CC: Julia Lawall <julia.lawall at lip6.fr>
---
drivers/gpu/drm/drm_syncobj.c | 41 ++++++++++++++++++++---------------
1 file changed, 24 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index b7eaa603f368..fab0a2cf672e 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -80,6 +80,23 @@ struct drm_syncobj_signal_pt {
struct list_head list;
};
+static DEFINE_SPINLOCK(signaled_fence_lock);
+static struct dma_fence signaled_fence;
+
+static struct dma_fence *drm_syncobj_signaled_fence_get(void)
+{
+ spin_lock(&signaled_fence_lock);
+ if (!signaled_fence.ops) {
+ dma_fence_init(&signaled_fence,
+ &drm_syncobj_stub_fence_ops,
+ &signaled_fence_lock,
+ 0, 0);
+ dma_fence_signal_locked(&signaled_fence);
+ }
+ spin_unlock(&signaled_fence_lock);
+
+ return dma_fence_get(&signaled_fence);
+}
/**
* drm_syncobj_find - lookup and reference a sync object.
* @file_private: drm file private pointer
@@ -111,24 +128,12 @@ static struct dma_fence
uint64_t point)
{
struct drm_syncobj_signal_pt *signal_pt;
+ struct dma_fence *f = NULL;
if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) &&
(point <= syncobj->timeline)) {
- struct drm_syncobj_stub_fence *fence =
- kzalloc(sizeof(struct drm_syncobj_stub_fence),
- GFP_KERNEL);
-
- if (!fence)
- return NULL;
- spin_lock_init(&fence->lock);
- dma_fence_init(&fence->base,
- &drm_syncobj_stub_fence_ops,
- &fence->lock,
- syncobj->timeline_context,
- point);
-
- dma_fence_signal(&fence->base);
- return &fence->base;
+ f = drm_syncobj_signaled_fence_get();
+ goto out;
}
list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) {
@@ -137,9 +142,11 @@ static struct dma_fence
if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) &&
(point != signal_pt->value))
continue;
- return dma_fence_get(&signal_pt->fence_array->base);
+ f = dma_fence_get(&signal_pt->fence_array->base);
+ goto out;
}
- return NULL;
+out:
+ return f;
}
static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
--
2.17.1
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