drm/src/drm_context.c

/*
 * Copyright (c) 2006, 2013, Oracle and/or its affiliates. All rights reserved.
 */

/*
 * Copyright (c) 2006, 2013 Intel Corporation.  All rights reserved.
 */

/**
 * \file drm_context.c
 * IOCTLs for generic contexts
 *
 * \author Rickard E. (Rik) Faith <faith@valinux.com>
 * \author Gareth Hughes <gareth@valinux.com>
 */

/*
 * Created: Fri Nov 24 18:31:37 2000 by gareth@valinux.com
 *
 * Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * ChangeLog:
 *  2001-11-16  Torsten Duwe <duwe@caldera.de>
 *      added context constructor/destructor hooks,
 *      needed by SiS driver's memory management.
 */

#include "drmP.h"
#include "drm_io32.h"

/******************************************************************/
/** \name Context bitmap support */
/*@{*/

/**
 * Free a handle from the context bitmap.
 *
 * \param dev DRM device.
 * \param ctx_handle context handle.
 *
 * Clears the bit specified by \p ctx_handle in drm_device::ctx_bitmap and the entry
 * in drm_device::ctx_idr, while holding the drm_device::struct_mutex
 * lock.
 */
void drm_ctxbitmap_free(struct drm_device * dev, int ctx_handle)
{
    mutex_lock(&dev->struct_mutex);
    (void) idr_remove(&dev->ctx_idr, ctx_handle);
    mutex_unlock(&dev->struct_mutex);
}

/**
 * Context bitmap allocation.
 *
 * \param dev DRM device.
 * \return (non-negative) context handle on success or a negative number on failure.
 *
 * Allocate a new idr from drm_device::ctx_idr while holding the
 * drm_device::struct_mutex lock.
 */
static int drm_ctxbitmap_next(struct drm_device * dev)
{
    int new_id;
    int ret;

again:
    if (idr_pre_get(&dev->ctx_idr, GFP_KERNEL) == 0) {
        DRM_ERROR("Out of memory expanding drawable idr\n");
        return -ENOMEM;
    }
    mutex_lock(&dev->struct_mutex);
    ret = idr_get_new_above(&dev->ctx_idr, NULL,
                DRM_RESERVED_CONTEXTS, &new_id);
        mutex_unlock(&dev->struct_mutex);
    if (ret == -EAGAIN)
        goto again;
    else if (ret)
        return ret;

    return new_id;
}

/**
 * Context bitmap initialization.
 *
 * \param dev DRM device.
 *
 * Initialise the drm_device::ctx_idr
 */
int drm_ctxbitmap_init(struct drm_device * dev)
{
    idr_init(&dev->ctx_idr);
    return 0;
}

/**
 * Context bitmap cleanup.
 *
 * \param dev DRM device.
 *
 * Free all idr members using drm_ctx_sarea_free helper function
 * while holding the drm_device::struct_mutex lock.
 */
void drm_ctxbitmap_cleanup(struct drm_device * dev)
{
    mutex_lock(&dev->struct_mutex);
    idr_remove_all(&dev->ctx_idr);
    mutex_unlock(&dev->struct_mutex);
}

/*@}*/

/******************************************************************/
/** \name Per Context SAREA Support */
/*@{*/

/**
 * Get per-context SAREA.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx_priv_map structure.
 * \return zero on success or a negative number on failure.
 *
 * Gets the map from drm_device::ctx_idr with the handle specified and
 * returns its handle.
 */
/* LINTED */
int drm_getsareactx(DRM_IOCTL_ARGS)
{
    struct drm_ctx_priv_map *request = data;
    struct drm_local_map *map;
    struct drm_map_list *_entry;

    mutex_lock(&dev->struct_mutex);

    map = idr_find(&dev->ctx_idr, request->ctx_id);
    if (!map) {
        mutex_unlock(&dev->struct_mutex);
        return -EINVAL;
    }

    request->handle = NULL;
    list_for_each_entry(_entry, struct drm_map_list, &dev->maplist, head) {
        if (_entry->map == map) {
            request->handle =
                (void *)(unsigned long)_entry->user_token;
            break;
        }
    }

    mutex_unlock(&dev->struct_mutex);

    if (request->handle == NULL)
        return -EINVAL;

    return 0;
}

/**
 * Set per-context SAREA.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx_priv_map structure.
 * \return zero on success or a negative number on failure.
 *
 * Searches the mapping specified in \p arg and update the entry in
 * drm_device::ctx_idr with it.
 */
/* LINTED */
int drm_setsareactx(DRM_IOCTL_ARGS)
{
    struct drm_ctx_priv_map *request = data;
    struct drm_local_map *map = NULL;
    struct drm_map_list *r_list = NULL;

    mutex_lock(&dev->struct_mutex);
    list_for_each_entry(r_list, struct drm_map_list, &dev->maplist, head) {
        if (r_list->map
            && r_list->user_token == (unsigned long) request->handle)
            goto found;
    }
      bad:
    mutex_unlock(&dev->struct_mutex);
    return -EINVAL;

      found:
    map = r_list->map;
    if (!map)
        goto bad;

    if (IS_ERR(idr_replace(&dev->ctx_idr, map, request->ctx_id)))
        goto bad;

    mutex_unlock(&dev->struct_mutex);

    return 0;
}

/*@}*/

/******************************************************************/
/** \name The actual DRM context handling routines */
/*@{*/

/**
 * Switch context.
 *
 * \param dev DRM device.
 * \param old old context handle.
 * \param new new context handle.
 * \return zero on success or a negative number on failure.
 *
 * Attempt to set drm_device::context_flag.
 */
static int drm_context_switch(struct drm_device * dev, int old, int new)
{
    if (test_and_set_bit(0, &dev->context_flag)) {
        DRM_ERROR("Reentering -- FIXME\n");
        return -EBUSY;
    }

    DRM_DEBUG("Context switch from %d to %d\n", old, new);

    if (new == dev->last_context) {
        clear_bit(0, &dev->context_flag);
        return 0;
    }

    return 0;
}

/**
 * Complete context switch.
 *
 * \param dev DRM device.
 * \param new new context handle.
 * \return zero on success or a negative number on failure.
 *
 * Updates drm_device::last_context and drm_device::last_switch. Verifies the
 * hardware lock is held, clears the drm_device::context_flag and wakes up
 * drm_device::context_wait.
 */
static int drm_context_switch_complete(struct drm_device *dev,
                       struct drm_file *file_priv, int new)
{
    dev->last_context = new;    /* PRE/POST: This is the _only_ writer. */
    dev->last_switch = jiffies;

    if (file_priv->master->lock.hw_lock != NULL &&
        !_DRM_LOCK_IS_HELD(file_priv->master->lock.hw_lock->lock)) {
        DRM_ERROR("Lock isn't held after context switch\n");
    }

    /* If a context switch is ever initiated
       when the kernel holds the lock, release
       that lock here. */
    clear_bit(0, &dev->context_flag);

    return 0;
}

/**
 * Reserve contexts.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx_res structure.
 * \return zero on success or a negative number on failure.
 */
/* LINTED */
int drm_resctx(DRM_IOCTL_ARGS)
{
    struct drm_ctx_res *res = data;
    struct drm_ctx ctx;
    int i;

    if (res->count >= DRM_RESERVED_CONTEXTS) {
        (void) memset(&ctx, 0, sizeof(ctx));
        for (i = 0; i < DRM_RESERVED_CONTEXTS; i++) {
            ctx.handle = i;
            DRM_COPYTO_WITH_RETURN(&res->contexts[i],
                &ctx, sizeof (ctx));
        }
    }
    res->count = DRM_RESERVED_CONTEXTS;

    return 0;
}

/**
 * Add context.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * Get a new handle for the context and copy to userspace.
 */
/* LINTED */
int drm_addctx(DRM_IOCTL_ARGS)
{
    struct drm_ctx_list *ctx_entry;
    struct drm_ctx *ctx = data;

    ctx->handle = drm_ctxbitmap_next(dev);
    if (ctx->handle == DRM_KERNEL_CONTEXT) {
        /* Skip kernel's context and get a new one. */
        ctx->handle = drm_ctxbitmap_next(dev);
    }
    DRM_DEBUG("%d\n", ctx->handle);
    /* LINTED */
    if (ctx->handle == -1) {
        DRM_DEBUG("Not enough free contexts.\n");
        /* Should this return -EBUSY instead? */
        return -ENOMEM;
    }

    ctx_entry = kmalloc(sizeof(*ctx_entry), GFP_KERNEL);
    if (!ctx_entry) {
        DRM_DEBUG("out of memory\n");
        return -ENOMEM;
    }

    INIT_LIST_HEAD(&ctx_entry->head);
    ctx_entry->handle = ctx->handle;
    ctx_entry->tag = file;

    mutex_lock(&dev->ctxlist_mutex);
    list_add(&ctx_entry->head, &dev->ctxlist, (caddr_t)ctx_entry);
    ++dev->ctx_count;
    mutex_unlock(&dev->ctxlist_mutex);

    return 0;
}

/* LINTED */
int drm_modctx(DRM_IOCTL_ARGS)
{
    /* This does nothing */
    return 0;
}

/**
 * Get context.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 */
/* LINTED */
int drm_getctx(DRM_IOCTL_ARGS)
{
    struct drm_ctx *ctx = data;

    /* This is 0, because we don't handle any context flags */
    ctx->flags = 0;

    return 0;
}

/**
 * Switch context.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * Calls context_switch().
 */
/* LINTED */
int drm_switchctx(DRM_IOCTL_ARGS)
{
    struct drm_ctx *ctx = data;

    DRM_DEBUG("%d\n", ctx->handle);
    return drm_context_switch(dev, dev->last_context, ctx->handle);
}

/**
 * New context.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * Calls context_switch_complete().
 */
/* LINTED */
int drm_newctx(DRM_IOCTL_ARGS)
{
    struct drm_ctx *ctx = data;

    DRM_DEBUG("%d\n", ctx->handle);
    (void) drm_context_switch_complete(dev, file, ctx->handle);

    return 0;
}

/**
 * Remove context.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * If not the special kernel context, calls ctxbitmap_free() to free the specified context.
 */
/* LINTED */
int drm_rmctx(DRM_IOCTL_ARGS)
{
    struct drm_ctx *ctx = data;

    DRM_DEBUG("%d\n", ctx->handle);
    if (ctx->handle != DRM_KERNEL_CONTEXT) {
        if (dev->driver->context_dtor)
            dev->driver->context_dtor(dev, ctx->handle);
        drm_ctxbitmap_free(dev, ctx->handle);
    }

    mutex_lock(&dev->ctxlist_mutex);
    if (!list_empty(&dev->ctxlist)) {
        struct drm_ctx_list *pos, *n;

        list_for_each_entry_safe(pos, n, struct drm_ctx_list, &dev->ctxlist, head) {
            if (pos->handle == ctx->handle) {
                list_del(&pos->head);
                kfree(pos, sizeof (*pos));
                --dev->ctx_count;
            }
        }
    }
    mutex_unlock(&dev->ctxlist_mutex);

    return 0;
}

/*@}*/