path: root/drivers/misc/vmw_vmci/vmci_context.c

/*
 * VMware VMCI Driver
 *
 * Copyright (C) 2012 VMware, Inc. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation version 2 and no later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 */

#include <linux/vmw_vmci_defs.h>
#include <linux/vmw_vmci_api.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include "vmci_queue_pair.h"
#include "vmci_datagram.h"
#include "vmci_doorbell.h"
#include "vmci_context.h"
#include "vmci_driver.h"
#include "vmci_event.h"

/*
 * List of current VMCI contexts.  Contexts can be added by
 * vmci_ctx_create() and removed via vmci_ctx_destroy().
 * These, along with context lookup, are protected by the
 * list structure's lock.
 */
static struct {
	struct list_head head;
	spinlock_t lock; /* Spinlock for context list operations */
} ctx_list = {
	.head = LIST_HEAD_INIT(ctx_list.head),
	.lock = __SPIN_LOCK_UNLOCKED(ctx_list.lock),
};

/* Used by contexts that did not set up notify flag pointers */
static bool ctx_dummy_notify;

static void ctx_signal_notify(struct vmci_ctx *context)
{
	*context->notify = true;
}

static void ctx_clear_notify(struct vmci_ctx *context)
{
	*context->notify = false;
}

/*
 * If nothing requires the attention of the guest, clears both
 * notify flag and call.
 */
static void ctx_clear_notify_call(struct vmci_ctx *context)
{
	if (context->pending_datagrams == 0 &&
	    vmci_handle_arr_get_size(context->pending_doorbell_array) == 0)
		ctx_clear_notify(context);
}

/*
 * Sets the context's notify flag iff datagrams are pending for this
 * context.  Called from vmci_setup_notify().
 */
void vmci_ctx_check_signal_notify(struct vmci_ctx *context)
{
	spin_lock(&context->lock);
	if (context->pending_datagrams)
		ctx_signal_notify(context);
	spin_unlock(&context->lock);
}

/*
 * Allocates and initializes a VMCI context.
 */
struct vmci_ctx *vmci_ctx_create(u32 cid, u32 priv_flags,
				 uintptr_t event_hnd,
				 int user_version,
				 const struct cred *cred)
{
	struct vmci_ctx *context;
	int error;

	if (cid == VMCI_INVALID_ID) {
		pr_devel("Invalid context ID for VMCI context\n");
		error = -EINVAL;
		goto err_out;
	}

	if (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS) {
		pr_devel("Invalid flag (flags=0x%x) for VMCI context\n",
			 priv_flags);
		error = -EINVAL;
		goto err_out;
	}

	if (user_version == 0) {
		pr_devel("Invalid suer_version %d\n", user_version);
		error = -EINVAL;
		goto err_out;
	}

	context = kzalloc(sizeof(*context), GFP_KERNEL);
	if (!context) {
		pr_warn("Failed to allocate memory for VMCI context\n");
		error = -EINVAL;
		goto err_out;
	}

	kref_init(&context->kref);
	spin_lock_init(&context->lock);
	INIT_LIST_HEAD(&context->list_item);
	INIT_LIST_HEAD(&context->datagram_queue);