[Intel-gfx] [RFC 03/12] drm/i915: Make GEM contexts track DRM clients

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

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

If we make GEM contexts keep a reference to i915_drm_client for the whole
of their lifetime, we can consolidate the current task pid and name usage
by getting it from the client.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c   | 23 +++++++++++---
 .../gpu/drm/i915/gem/i915_gem_context_types.h | 13 ++------
 drivers/gpu/drm/i915/i915_debugfs.c           | 31 +++++++++----------
 drivers/gpu/drm/i915/i915_gpu_error.c         | 21 +++++++------
 4 files changed, 48 insertions(+), 40 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 2c3fd9748d39..0f4150c8d7fe 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -300,8 +300,13 @@ static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx)
 
 static void i915_gem_context_free(struct i915_gem_context *ctx)
 {
+	struct i915_drm_client *client = ctx->client;
+
 	GEM_BUG_ON(!i915_gem_context_is_closed(ctx));
 
+	if (client)
+		i915_drm_client_put(client);
+
 	spin_lock(&ctx->i915->gem.contexts.lock);
 	list_del(&ctx->link);
 	spin_unlock(&ctx->i915->gem.contexts.lock);
@@ -311,7 +316,6 @@ static void i915_gem_context_free(struct i915_gem_context *ctx)
 	if (ctx->timeline)
 		intel_timeline_put(ctx->timeline);
 
-	put_pid(ctx->pid);
 	mutex_destroy(&ctx->mutex);
 
 	kfree_rcu(ctx, rcu);
@@ -899,6 +903,7 @@ static int gem_context_register(struct i915_gem_context *ctx,
 				struct drm_i915_file_private *fpriv,
 				u32 *id)
 {
+	struct i915_drm_client *client;
 	struct i915_address_space *vm;
 	int ret;
 
@@ -910,15 +915,25 @@ static int gem_context_register(struct i915_gem_context *ctx,
 		WRITE_ONCE(vm->file, fpriv); /* XXX */
 	mutex_unlock(&ctx->mutex);
 
-	ctx->pid = get_task_pid(current, PIDTYPE_PID);
+	client = i915_drm_client_get(fpriv->client);
+
+	rcu_read_lock();
 	snprintf(ctx->name, sizeof(ctx->name), "%s[%d]",
-		 current->comm, pid_nr(ctx->pid));
+		 rcu_dereference(client->name),
+		 pid_nr(rcu_dereference(client->pid)));
+	rcu_read_unlock();
 
 	/* And finally expose ourselves to userspace via the idr */
 	ret = xa_alloc(&fpriv->context_xa, id, ctx, xa_limit_32b, GFP_KERNEL);
 	if (ret)
-		put_pid(fetch_and_zero(&ctx->pid));
+		goto err;
+
+	ctx->client = client;
 
+	return 0;
+
+err:
+	i915_drm_client_put(client);
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
index 28760bd03265..b0e03380c690 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
@@ -96,20 +96,13 @@ struct i915_gem_context {
 	 */
 	struct i915_address_space __rcu *vm;
 
-	/**
-	 * @pid: process id of creator
-	 *
-	 * Note that who created the context may not be the principle user,
-	 * as the context may be shared across a local socket. However,
-	 * that should only affect the default context, all contexts created
-	 * explicitly by the client are expected to be isolated.
-	 */
-	struct pid *pid;
-
 	/** link: place with &drm_i915_private.context_list */
 	struct list_head link;
 	struct llist_node free_link;
 
+	/** client: struct i915_drm_client */
+	struct i915_drm_client *client;
+
 	/**
 	 * @ref: reference count
 	 *
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 8f2525e4ce0f..0655f1e7527d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -330,17 +330,17 @@ static void print_context_stats(struct seq_file *m,
 				.vm = rcu_access_pointer(ctx->vm),
 			};
 			struct drm_file *file = ctx->file_priv->file;
-			struct task_struct *task;
 			char name[80];
 
 			rcu_read_lock();
+
 			idr_for_each(&file->object_idr, per_file_stats, &stats);
-			rcu_read_unlock();
 
-			rcu_read_lock();
-			task = pid_task(ctx->pid ?: file->pid, PIDTYPE_PID);
 			snprintf(name, sizeof(name), "%s",
-				 task ? task->comm : "<unknown>");
+				 I915_SELFTEST_ONLY(!ctx->client) ?
+				 "[kernel]" :
+				 rcu_dereference(ctx->client->name));
+
 			rcu_read_unlock();
 
 			print_file_stats(m, name, stats);
@@ -1273,19 +1273,16 @@ static int i915_context_status(struct seq_file *m, void *unused)
 		spin_unlock(&i915->gem.contexts.lock);
 
 		seq_puts(m, "HW context ");
-		if (ctx->pid) {
-			struct task_struct *task;
-
-			task = get_pid_task(ctx->pid, PIDTYPE_PID);
-			if (task) {
-				seq_printf(m, "(%s [%d]) ",
-					   task->comm, task->pid);
-				put_task_struct(task);
-			}
-		} else if (IS_ERR(ctx->file_priv)) {
-			seq_puts(m, "(deleted) ");
+
+		if (I915_SELFTEST_ONLY(!ctx->client)) {
+			seq_puts(m, "([kernel]) ");
 		} else {
-			seq_puts(m, "(kernel) ");
+			rcu_read_lock();
+			seq_printf(m, "(%s [%d]) %s",
+				   rcu_dereference(ctx->client->name),
+				   pid_nr(rcu_dereference(ctx->client->pid)),
+				   ctx->client->closed ? "(closed) " : "");
+			rcu_read_unlock();
 		}
 
 		seq_putc(m, ctx->remap_slice ? 'R' : 'r');
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 2a4cd0ba5464..653e1bc5050e 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1221,7 +1221,8 @@ static void record_request(const struct i915_request *request,
 	rcu_read_lock();
 	ctx = rcu_dereference(request->context->gem_context);
 	if (ctx)
-		erq->pid = pid_nr(ctx->pid);
+		erq->pid = I915_SELFTEST_ONLY(!ctx->client) ?
+			   0 : pid_nr(rcu_dereference(ctx->client->pid));
 	rcu_read_unlock();
 }
 
@@ -1241,23 +1242,25 @@ static bool record_context(struct i915_gem_context_coredump *e,
 			   const struct i915_request *rq)
 {
 	struct i915_gem_context *ctx;
-	struct task_struct *task;
 	bool simulated;
 
 	rcu_read_lock();
+
 	ctx = rcu_dereference(rq->context->gem_context);
 	if (ctx && !kref_get_unless_zero(&ctx->ref))
 		ctx = NULL;
-	rcu_read_unlock();
-	if (!ctx)
+	if (!ctx) {
+		rcu_read_unlock();
 		return true;
+	}
 
-	rcu_read_lock();
-	task = pid_task(ctx->pid, PIDTYPE_PID);
-	if (task) {
-		strcpy(e->comm, task->comm);
-		e->pid = task->pid;
+	if (I915_SELFTEST_ONLY(!ctx->client)) {
+		strcpy(e->comm, "[kernel]");
+	} else {
+		strcpy(e->comm, rcu_dereference(ctx->client->name));
+		e->pid = pid_nr(rcu_dereference(ctx->client->pid));
 	}
+
 	rcu_read_unlock();
 
 	e->sched_attr = ctx->sched;
-- 
2.20.1

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