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drm/msm: Fix debugfs deadlock

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In normal cases the gem obj lock is acquired first before mm_lock.  The
exception is iterating the various object lists.  In the shrinker path,
deadlock is avoided by using msm_gem_trylock() and skipping over objects
that cannot be locked.  But for debugfs the straightforward thing is to
split things out into a separate list of all objects protected by it's
own lock.

Fixes: d984457b31 ("drm/msm: Add priv->mm_lock to protect active/inactive lists")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20210401012722.527712-4-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>
This commit is contained in:
Rob Clark 2021-03-31 18:27:20 -07:00
parent cc8a4d5a1b
commit 6ed0897cd8
5 changed files with 35 additions and 15 deletions
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14
drivers/gpu/drm/msm/msm_debugfs.c
View file

@ -111,23 +111,15 @@ static const struct file_operations msm_gpu_fops = {
static int msm_gem_show(struct drm_device *dev, struct seq_file *m)
{
struct msm_drm_private *priv = dev->dev_private;
struct msm_gpu *gpu = priv->gpu;
int ret;
ret = mutex_lock_interruptible(&priv->mm_lock);
ret = mutex_lock_interruptible(&priv->obj_lock);
if (ret)
return ret;
if (gpu) {
seq_printf(m, "Active Objects (%s):\n", gpu->name);
msm_gem_describe_objects(&gpu->active_list, m);
}
msm_gem_describe_objects(&priv->objects, m);
seq_printf(m, "Inactive Objects:\n");
msm_gem_describe_objects(&priv->inactive_dontneed, m);
msm_gem_describe_objects(&priv->inactive_willneed, m);
mutex_unlock(&priv->mm_lock);
mutex_unlock(&priv->obj_lock);
return 0;
}

3
drivers/gpu/drm/msm/msm_drv.c
View file

@ -446,6 +446,9 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
priv->wq = alloc_ordered_workqueue("msm", 0);
INIT_LIST_HEAD(&priv->objects);
mutex_init(&priv->obj_lock);
INIT_LIST_HEAD(&priv->inactive_willneed);
INIT_LIST_HEAD(&priv->inactive_dontneed);
INIT_LIST_HEAD(&priv->inactive_purged);

9
drivers/gpu/drm/msm/msm_drv.h
View file

@ -174,7 +174,14 @@ struct msm_drm_private {
struct msm_rd_state *hangrd; /* debugfs to dump hanging submits */
struct msm_perf_state *perf;
/*
/**
* List of all GEM objects (mainly for debugfs, protected by obj_lock
* (acquire before per GEM object lock)
*/
struct list_head objects;
struct mutex obj_lock;
/**
* Lists of inactive GEM objects. Every bo is either in one of the
* inactive lists (depending on whether or not it is shrinkable) or
* gpu->active_list (for the gpu it is active on[1])

14
drivers/gpu/drm/msm/msm_gem.c
View file

@ -961,7 +961,7 @@ void msm_gem_describe_objects(struct list_head *list, struct seq_file *m)
size_t size = 0;
seq_puts(m, " flags id ref offset kaddr size madv name\n");
list_for_each_entry(msm_obj, list, mm_list) {
list_for_each_entry(msm_obj, list, node) {
struct drm_gem_object *obj = &msm_obj->base;
seq_puts(m, " ");
msm_gem_describe(obj, m);
@ -980,6 +980,10 @@ void msm_gem_free_object(struct drm_gem_object *obj)
struct drm_device *dev = obj->dev;
struct msm_drm_private *priv = dev->dev_private;
mutex_lock(&priv->obj_lock);
list_del(&msm_obj->node);
mutex_unlock(&priv->obj_lock);
mutex_lock(&priv->mm_lock);
if (msm_obj->dontneed)
mark_unpurgable(msm_obj);
@ -1169,6 +1173,10 @@ static struct drm_gem_object *_msm_gem_new(struct drm_device *dev,
list_add_tail(&msm_obj->mm_list, &priv->inactive_willneed);
mutex_unlock(&priv->mm_lock);
mutex_lock(&priv->obj_lock);
list_add_tail(&msm_obj->node, &priv->objects);
mutex_unlock(&priv->obj_lock);
return obj;
fail:
@ -1239,6 +1247,10 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,
list_add_tail(&msm_obj->mm_list, &priv->inactive_willneed);
mutex_unlock(&priv->mm_lock);
mutex_lock(&priv->obj_lock);
list_add_tail(&msm_obj->node, &priv->objects);
mutex_unlock(&priv->obj_lock);
return obj;
fail:

10
drivers/gpu/drm/msm/msm_gem.h
View file

@ -60,10 +60,16 @@ struct msm_gem_object {
*/
uint8_t vmap_count;
/**
* Node in list of all objects (mainly for debugfs, protected by
* priv->obj_lock
*/
struct list_head node;
/**
* An object is either:
* inactive - on priv->inactive_dontneed/willneed/purged depending
* on status
* inactive - on priv->inactive_dontneed or priv->inactive_willneed
* (depending on purgability status)
* active - on one one of the gpu's active_list.. well, at
* least for now we don't have (I don't think) hw sync between
* 2d and 3d one devices which have both, meaning we need to