drm: Move legacy device list out of drm_driver

The drm_driver structure contains a single field (legacy_dev_list) that
is modified by the DRM core, used to store a linked list of legacy DRM
devices associated with the driver. In order to make the structure
const, move the field out to a global variable. This requires locking
access to the global where the local field didn't require serialization,
but this only affects legacy drivers, and isn't in any hot path.

While at it, compile-out the legacy_dev_list field when DRM_LEGACY isn't
defined.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 6dba4b8ce4fe2fd438f4d09ff870151a5e7255ec..dfb138aaccba9425a3efaa41a7ac0ee45f9b3b2f 100644 (file)
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -24,6 +24,8 @@
 
 #include <linux/dma-mapping.h>
 #include <linux/export.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
 #include <linux/pci.h>
 #include <linux/slab.h>
 
@@ -36,6 +38,9 @@
 #include "drm_legacy.h"
 
 #ifdef CONFIG_DRM_LEGACY
+/* List of devices hanging off drivers with stealth attach. */
+static LIST_HEAD(legacy_dev_list);
+static DEFINE_MUTEX(legacy_dev_list_lock);
 
 /**
  * drm_pci_alloc - Allocate a PCI consistent memory block, for DMA.
@@ -225,10 +230,11 @@ static int drm_get_pci_dev(struct pci_dev *pdev,
        if (ret)
                goto err_agp;
 
-       /* No locking needed since shadow-attach is single-threaded since it may
-        * only be called from the per-driver module init hook. */
-       if (drm_core_check_feature(dev, DRIVER_LEGACY))
-               list_add_tail(&dev->legacy_dev_list, &driver->legacy_dev_list);
+       if (drm_core_check_feature(dev, DRIVER_LEGACY)) {
+               mutex_lock(&legacy_dev_list_lock);
+               list_add_tail(&dev->legacy_dev_list, &legacy_dev_list);
+               mutex_unlock(&legacy_dev_list_lock);
+       }
 
        return 0;
 
@@ -261,7 +267,6 @@ int drm_legacy_pci_init(struct drm_driver *driver, struct pci_driver *pdriver)
                return -EINVAL;
 
        /* If not using KMS, fall back to stealth mode manual scanning. */
-       INIT_LIST_HEAD(&driver->legacy_dev_list);
        for (i = 0; pdriver->id_table[i].vendor != 0; i++) {
                pid = &pdriver->id_table[i];
 
@@ -304,11 +309,15 @@ void drm_legacy_pci_exit(struct drm_driver *driver, struct pci_driver *pdriver)
        if (!(driver->driver_features & DRIVER_LEGACY)) {
                WARN_ON(1);
        } else {
-               list_for_each_entry_safe(dev, tmp, &driver->legacy_dev_list,
+               mutex_lock(&legacy_dev_list_lock);
+               list_for_each_entry_safe(dev, tmp, &legacy_dev_list,
                                         legacy_dev_list) {
-                       list_del(&dev->legacy_dev_list);
-                       drm_put_dev(dev);
+                       if (dev->driver == driver) {
+                               list_del(&dev->legacy_dev_list);
+                               drm_put_dev(dev);
+                       }
                }
+               mutex_unlock(&legacy_dev_list_lock);
        }
        DRM_INFO("Module unloaded\n");
 }

diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index 283a93ce4617261470a43354a9466852ab149240..bd5abe7cd48f67719c885e8b6d038bfb4cebaccc 100644 (file)
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -51,13 +51,6 @@ enum switch_power_state {
  * may contain multiple heads.
  */
 struct drm_device {
-       /**
-        * @legacy_dev_list:
-        *
-        * List of devices per driver for stealth attach cleanup
-        */
-       struct list_head legacy_dev_list;
-
        /** @if_version: Highest interface version set */
        int if_version;
 
@@ -336,6 +329,9 @@ struct drm_device {
        /* Everything below here is for legacy driver, never use! */
        /* private: */
 #if IS_ENABLED(CONFIG_DRM_LEGACY)
+       /* List of devices per driver for stealth attach cleanup */
+       struct list_head legacy_dev_list;
+
        /* Context handle management - linked list of context handles */
        struct list_head ctxlist;
 

diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index 02787319246a9b80c83474bbe3fb971e88877b0d..827838e0a97e6c2d2f50ae92a2715a227919ce29 100644 (file)
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -499,8 +499,6 @@ struct drm_driver {
        /* Everything below here is for legacy driver, never use! */
        /* private: */
 
-       /* List of devices hanging off this driver with stealth attach. */
-       struct list_head legacy_dev_list;
        int (*firstopen) (struct drm_device *);
        void (*preclose) (struct drm_device *, struct drm_file *file_priv);
        int (*dma_ioctl) (struct drm_device *dev, void *data, struct drm_file *file_priv);