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drm/udl: Get rid of dev->struct_mutex usage

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It's only used to protect our page list, and only when we know we have
a full reference. This means none of these code paths can ever race
with the final unref, and hence we do not need dev->struct_mutex
serialization and can simply switch to our own locking.

For more context the only magic the locked gem_free_object provides is
that it prevents concurrent final unref (and destruction) of gem
objects while anyone is holding dev->struct_mutex. This was used by
i915 (and other drivers) to implement eviction handling with less
headaches.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180327082356.24516-3-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2018-03-27 10:23:54 +02:00
parent fcb1e57f79
commit ae358dacd2
5 changed files with 11 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/gpu/drm/udl/udl_dmabuf.c
View File

@ -76,6 +76,7 @@ static struct sg_table *udl_map_dma_buf(struct dma_buf_attachment *attach,
struct udl_drm_dmabuf_attachment *udl_attach = attach->priv;
struct udl_gem_object *obj = to_udl_bo(attach->dmabuf->priv);
struct drm_device *dev = obj->base.dev;
struct udl_device *udl = dev->dev_private;
struct scatterlist *rd, *wr;
struct sg_table *sgt = NULL;
unsigned int i;
@ -112,7 +113,7 @@ static struct sg_table *udl_map_dma_buf(struct dma_buf_attachment *attach,
return ERR_PTR(-ENOMEM);
}
mutex_lock(&dev->struct_mutex);
mutex_lock(&udl->gem_lock);
rd = obj->sg->sgl;
wr = sgt->sgl;
@ -137,7 +138,7 @@ static struct sg_table *udl_map_dma_buf(struct dma_buf_attachment *attach,
attach->priv = udl_attach;
err_unlock:
mutex_unlock(&dev->struct_mutex);
mutex_unlock(&udl->gem_lock);
return sgt;
}

2
drivers/gpu/drm/udl/udl_drv.c
View File

@ -53,7 +53,7 @@ static struct drm_driver driver = {
.unload = udl_driver_unload,
/* gem hooks */
.gem_free_object = udl_gem_free_object,
.gem_free_object_unlocked = udl_gem_free_object,
.gem_vm_ops = &udl_gem_vm_ops,
.dumb_create = udl_dumb_create,

2
drivers/gpu/drm/udl/udl_drv.h
View File

@ -54,6 +54,8 @@ struct udl_device {
struct usb_device *udev;
struct drm_crtc *crtc;
struct mutex gem_lock;
int sku_pixel_limit;
struct urb_list urbs;

5
drivers/gpu/drm/udl/udl_gem.c
View File

@ -214,9 +214,10 @@ int udl_gem_mmap(struct drm_file *file, struct drm_device *dev,
{
struct udl_gem_object *gobj;
struct drm_gem_object *obj;
struct udl_device *udl = dev->dev_private;
int ret = 0;
mutex_lock(&dev->struct_mutex);
mutex_lock(&udl->gem_lock);
obj = drm_gem_object_lookup(file, handle);
if (obj == NULL) {
ret = -ENOENT;
@ -236,6 +237,6 @@ int udl_gem_mmap(struct drm_file *file, struct drm_device *dev,
out:
drm_gem_object_put(&gobj->base);
unlock:
mutex_unlock(&dev->struct_mutex);
mutex_unlock(&udl->gem_lock);
return ret;
}

2
drivers/gpu/drm/udl/udl_main.c
View File

@ -324,6 +324,8 @@ int udl_driver_load(struct drm_device *dev, unsigned long flags)
udl->ddev = dev;
dev->dev_private = udl;
mutex_init(&udl->gem_lock);
if (!udl_parse_vendor_descriptor(dev, udl->udev)) {
ret = -ENODEV;
DRM_ERROR("firmware not recognized. Assume incompatible device\n");