[RFC 5/8] drm/i915: Keep track of registered clients indexed by task struct

Tvrtko Ursulin
2021-10-04T14:45:29Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

A simple hash table of registered clients indexed by the task struct
pointer is kept to be used in a following patch.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 2 ++
drivers/gpu/drm/i915/i915_drm_client.c | 31 ++++++++++++++++++++-
drivers/gpu/drm/i915/i915_drm_client.h | 13 +++++++++
3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index d1992ba59ed8..8d4d687ab1d0 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -1932,6 +1932,8 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
return -EIO;
}

+ i915_drm_client_update_owner(ext_data.fpriv->client, current);
+
ext_data.pc = proto_context_create(i915, args->flags);
if (IS_ERR(ext_data.pc))
return PTR_ERR(ext_data.pc);
diff --git a/drivers/gpu/drm/i915/i915_drm_client.c b/drivers/gpu/drm/i915/i915_drm_client.c
index 91a8559bebf7..82b9636482ef 100644
--- a/drivers/gpu/drm/i915/i915_drm_client.c
+++ b/drivers/gpu/drm/i915/i915_drm_client.c
@@ -18,6 +18,9 @@ void i915_drm_clients_init(struct i915_drm_clients *clients,
clients->next_id = 0;

xa_init_flags(&clients->xarray, XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ);
+
+ rwlock_init(&clients->lock);
+ hash_init(clients->tasks);
}

struct i915_drm_client *i915_drm_client_add(struct i915_drm_clients *clients)
@@ -42,6 +45,8 @@ struct i915_drm_client *i915_drm_client_add(struct i915_drm_clients *clients)
INIT_LIST_HEAD(&client->ctx_list);
client->clients = clients;

+ i915_drm_client_update_owner(client, current);
+
return client;

err:
@@ -54,9 +59,14 @@ void __i915_drm_client_free(struct kref *kref)
{
struct i915_drm_client *client =
container_of(kref, typeof(*client), kref);
- struct xarray *xa = &client->clients->xarray;
+ struct i915_drm_clients *clients = client->clients;
+ struct xarray *xa = &clients->xarray;
unsigned long flags;

+ write_lock(&clients->lock);
+ hash_del(&client->node);
+ write_unlock(&clients->lock);
+
xa_lock_irqsave(xa, flags);
__xa_erase(xa, client->id);
xa_unlock_irqrestore(xa, flags);
@@ -68,3 +78,22 @@ void i915_drm_clients_fini(struct i915_drm_clients *clients)
GEM_BUG_ON(!xa_empty(&clients->xarray));
xa_destroy(&clients->xarray);
}
+
+void i915_drm_client_update_owner(struct i915_drm_client *client,
+ struct task_struct *owner)
+{
+ struct i915_drm_clients *clients;
+
+ if (READ_ONCE(client->owner) == owner)
+ return;
+
+ clients = client->clients;
+ write_lock(&clients->lock);
+ if (READ_ONCE(client->owner) != owner) {
+ if (client->owner)
+ hash_del(&client->node);
+ client->owner = owner;
+ hash_add(clients->tasks, &client->node, (uintptr_t)owner);
+ }
+ write_unlock(&clients->lock);
+}
diff --git a/drivers/gpu/drm/i915/i915_drm_client.h b/drivers/gpu/drm/i915/i915_drm_client.h
index 0207dfad4568..42fd79f0558a 100644
--- a/drivers/gpu/drm/i915/i915_drm_client.h
+++ b/drivers/gpu/drm/i915/i915_drm_client.h
@@ -6,8 +6,11 @@
#ifndef __I915_DRM_CLIENT_H__
#define __I915_DRM_CLIENT_H__

+#include <linux/hashtable.h>
#include <linux/kref.h>
#include <linux/list.h>
+#include <linux/rwlock.h>
+#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/xarray.h>

@@ -18,6 +21,9 @@ struct i915_drm_clients {

struct xarray xarray;
u32 next_id;
+
+ rwlock_t lock;
+ DECLARE_HASHTABLE(tasks, 6);
};

struct i915_drm_client {
@@ -28,6 +34,9 @@ struct i915_drm_client {
spinlock_t ctx_lock; /* For add/remove from ctx_list. */
struct list_head ctx_list; /* List of contexts belonging to client. */

+ struct task_struct *owner; /* No reference kept, never dereferenced. */
+ struct hlist_node node;
+
struct i915_drm_clients *clients;
};

@@ -52,4 +61,8 @@ struct i915_drm_client *i915_drm_client_add(struct i915_drm_clients *clients);

void i915_drm_clients_fini(struct i915_drm_clients *clients);

+void i915_drm_client_update_owner(struct i915_drm_client *client,
+ struct task_struct *owner);
+
+
#endif /* !__I915_DRM_CLIENT_H__ */
--
2.30.2