099d1c290e
Lets not trick ourselves into thinking "drm_device" objects are not ref-counted. That's just utterly stupid. We manage "drm_minor" objects on each drm-device and each minor can have an unlimited number of open handles. Each of these handles has the drm_minor (and thus the drm_device) as private-data in the file-handle. Therefore, we may not destroy "drm_device" until all these handles are closed. It is *not* possible to reset all these pointers atomically and restrict access to them, and this is *not* how this is done! Instead, we use ref-counts to make sure the object is valid and not freed. Note that we currently use "dev->open_count" for that, which is *exactly* the same as a reference-count, just open coded. So this patch doesn't change any semantics on DRM devices (well, this patch just introduces the ref-count, anyway. Follow-up patches will replace open_count by it). Also note that generic VFS revoke support could allow us to drop this ref-count again. We could then just synchronously disable any fops->xy() calls. However, this is not the case, yet, and no such patches are in sight (and I seriously question the idea of dropping the ref-cnt again). Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
/*
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* Copyright (C) 2013 NVIDIA Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include "drm.h"
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static int drm_host1x_set_busid(struct drm_device *dev,
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struct drm_master *master)
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{
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const char *device = dev_name(dev->dev);
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const char *driver = dev->driver->name;
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const char *bus = dev->dev->bus->name;
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int length;
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master->unique_len = strlen(bus) + 1 + strlen(device);
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master->unique_size = master->unique_len;
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master->unique = kmalloc(master->unique_len + 1, GFP_KERNEL);
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if (!master->unique)
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return -ENOMEM;
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snprintf(master->unique, master->unique_len + 1, "%s:%s", bus, device);
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length = strlen(driver) + 1 + master->unique_len;
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dev->devname = kmalloc(length + 1, GFP_KERNEL);
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if (!dev->devname)
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return -ENOMEM;
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snprintf(dev->devname, length + 1, "%s@%s", driver, master->unique);
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return 0;
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}
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static struct drm_bus drm_host1x_bus = {
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.bus_type = DRIVER_BUS_HOST1X,
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.set_busid = drm_host1x_set_busid,
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};
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int drm_host1x_init(struct drm_driver *driver, struct host1x_device *device)
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{
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struct drm_device *drm;
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int ret;
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driver->bus = &drm_host1x_bus;
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drm = drm_dev_alloc(driver, &device->dev);
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if (!drm)
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return -ENOMEM;
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ret = drm_dev_register(drm, 0);
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if (ret)
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goto err_free;
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DRM_INFO("Initialized %s %d.%d.%d %s on minor %d\n", driver->name,
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driver->major, driver->minor, driver->patchlevel,
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driver->date, drm->primary->index);
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return 0;
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err_free:
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drm_dev_unref(drm);
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return ret;
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}
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void drm_host1x_exit(struct drm_driver *driver, struct host1x_device *device)
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{
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struct tegra_drm *tegra = dev_get_drvdata(&device->dev);
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drm_put_dev(tegra->drm);
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}
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