[PATCH] drm/amdgpu: create fence slab once when amdgpu module init.

[Alex Deucher]

From: Rex Zhu <rex....@amd.com>

This avoids problems with multiple GPUs.  For example,
if the first GPU failed before amdgpu_fence_init() was
called, amdgpu_fence_slab_ref is still 0 and it will
get decremented in amdgpu_fence_driver_fini().  This
will lead to a crash during init of the second GPU since
amdgpu_fence_slab_ref is not 0.

v2: add functions for init/exit instead of
    moving the variables into the driver.

Signed-off-by: Rex Zhu <Rex.Zhu at amd.com>
Reviewed-by: Christian König <christian.koenig at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h       |  2 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c   |  5 ++++-
 drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 25 ++++++++++++++-----------
 3 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 2a009c3..992f00b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -602,6 +602,8 @@ int amdgpu_sync_wait(struct amdgpu_sync *sync);
 void amdgpu_sync_free(struct amdgpu_sync *sync);
 int amdgpu_sync_init(void);
 void amdgpu_sync_fini(void);
+int amdgpu_fence_slab_init(void);
+void amdgpu_fence_slab_fini(void);

 /*
  * GART structures, functions & helpers
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 0dee008..6ff5879 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -565,9 +565,12 @@ static struct pci_driver amdgpu_kms_pci_driver = {
        .driver.pm = &amdgpu_pm_ops,
 };

+
+
 static int __init amdgpu_init(void)
 {
        amdgpu_sync_init();
+       amdgpu_fence_slab_init();
        if (vgacon_text_force()) {
                DRM_ERROR("VGACON disables amdgpu kernel modesetting.\n");
                return -EINVAL;
@@ -578,7 +581,6 @@ static int __init amdgpu_init(void)
        driver->driver_features |= DRIVER_MODESET;
        driver->num_ioctls = amdgpu_max_kms_ioctl;
        amdgpu_register_atpx_handler();
-
        /* let modprobe override vga console setting */
        return drm_pci_init(driver, pdriver);
 }
@@ -589,6 +591,7 @@ static void __exit amdgpu_exit(void)
        drm_pci_exit(driver, pdriver);
        amdgpu_unregister_atpx_handler();
        amdgpu_sync_fini();
+       amdgpu_fence_slab_fini();
 }

 module_init(amdgpu_init);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index ba9c042..7eb2fca8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -55,8 +55,21 @@ struct amdgpu_fence {
 };

 static struct kmem_cache *amdgpu_fence_slab;
-static atomic_t amdgpu_fence_slab_ref = ATOMIC_INIT(0);

+int amdgpu_fence_slab_init(void)
+{
+       amdgpu_fence_slab = kmem_cache_create(
+               "amdgpu_fence", sizeof(struct amdgpu_fence), 0,
+               SLAB_HWCACHE_ALIGN, NULL);
+       if (!amdgpu_fence_slab)
+               return -ENOMEM;
+       return 0;
+}
+
+void amdgpu_fence_slab_fini(void)
+{
+       kmem_cache_destroy(amdgpu_fence_slab);
+}
 /*
  * Cast helper
  */
@@ -396,13 +409,6 @@ int amdgpu_fence_driver_init_ring(struct amdgpu_ring *ring,
  */
 int amdgpu_fence_driver_init(struct amdgpu_device *adev)
 {
-       if (atomic_inc_return(&amdgpu_fence_slab_ref) == 1) {
-               amdgpu_fence_slab = kmem_cache_create(
-                       "amdgpu_fence", sizeof(struct amdgpu_fence), 0,
-                       SLAB_HWCACHE_ALIGN, NULL);
-               if (!amdgpu_fence_slab)
-                       return -ENOMEM;
-       }
        if (amdgpu_debugfs_fence_init(adev))
                dev_err(adev->dev, "fence debugfs file creation failed\n");

@@ -441,9 +447,6 @@ void amdgpu_fence_driver_fini(struct amdgpu_device *adev)
                kfree(ring->fence_drv.fences);
                ring->fence_drv.initialized = false;
        }
-
-       if (atomic_dec_and_test(&amdgpu_fence_slab_ref))
-               kmem_cache_destroy(amdgpu_fence_slab);
 }

 /**
-- 
2.5.5