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drm_context.c

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/**
 * \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"

/******************************************************************/
/** \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.
 */
00059 void drm_ctxbitmap_free(struct drm_device * dev, int ctx_handle)
{
      mutex_lock(&dev->struct_mutex);
      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.
 */
00075 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);
      if (ret == -EAGAIN) {
            mutex_unlock(&dev->struct_mutex);
            goto again;
      }
      mutex_unlock(&dev->struct_mutex);
      return new_id;
}

/**
 * Context bitmap initialization.
 *
 * \param dev DRM device.
 *
 * Initialise the drm_device::ctx_idr
 */
00103 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.
 */
00117 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.
 */
00142 int drm_getsareactx(struct drm_device *dev, void *data,
                struct drm_file *file_priv)
{
      struct drm_ctx_priv_map *request = data;
      struct drm_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;
      }

      mutex_unlock(&dev->struct_mutex);

      request->handle = NULL;
      list_for_each_entry(_entry, &dev->maplist, head) {
            if (_entry->map == map) {
                  request->handle = 
                      (void *)(unsigned long)_entry->user_token;
                  break;
            }
      }
      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.
 */
00185 int drm_setsareactx(struct drm_device *dev, void *data,
                struct drm_file *file_priv)
{
      struct drm_ctx_priv_map *request = data;
      struct drm_map *map = NULL;
      struct drm_map_list *r_list = NULL;

      mutex_lock(&dev->struct_mutex);
      list_for_each_entry(r_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.
 */
00231 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.
 */
00259 static int drm_context_switch_complete(struct drm_device * dev, int new)
{
      dev->last_context = new;      /* PRE/POST: This is the _only_ writer. */
      dev->last_switch = jiffies;

      if (!_DRM_LOCK_IS_HELD(dev->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);
      wake_up(&dev->context_wait);

      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.
 */
00286 int drm_resctx(struct drm_device *dev, void *data,
             struct drm_file *file_priv)
{
      struct drm_ctx_res *res = data;
      struct drm_ctx ctx;
      int i;

      if (res->count >= DRM_RESERVED_CONTEXTS) {
            memset(&ctx, 0, sizeof(ctx));
            for (i = 0; i < DRM_RESERVED_CONTEXTS; i++) {
                  ctx.handle = i;
                  if (copy_to_user(&res->contexts[i], &ctx, sizeof(ctx)))
                        return -EFAULT;
            }
      }
      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.
 */
00317 int drm_addctx(struct drm_device *dev, void *data,
             struct drm_file *file_priv)
{
      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);
      if (ctx->handle == -1) {
            DRM_DEBUG("Not enough free contexts.\n");
            /* Should this return -EBUSY instead? */
            return -ENOMEM;
      }

      if (ctx->handle != DRM_KERNEL_CONTEXT) {
            if (dev->driver->context_ctor)
                  if (!dev->driver->context_ctor(dev, ctx->handle)) {
                        DRM_DEBUG("Running out of ctxs or memory.\n");
                        return -ENOMEM;
                  }
      }

      ctx_entry = drm_alloc(sizeof(*ctx_entry), DRM_MEM_CTXLIST);
      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_priv;

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

      return 0;
}

int drm_modctx(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
      /* 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.
 */
00376 int drm_getctx(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
      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().
 */
00397 int drm_switchctx(struct drm_device *dev, void *data,
              struct drm_file *file_priv)
{
      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().
 */
00417 int drm_newctx(struct drm_device *dev, void *data,
             struct drm_file *file_priv)
{
      struct drm_ctx *ctx = data;

      DRM_DEBUG("%d\n", ctx->handle);
      drm_context_switch_complete(dev, 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.
 */
00439 int drm_rmctx(struct drm_device *dev, void *data,
            struct drm_file *file_priv)
{
      struct drm_ctx *ctx = data;

      DRM_DEBUG("%d\n", ctx->handle);
      if (ctx->handle == DRM_KERNEL_CONTEXT + 1) {
            file_priv->remove_auth_on_close = 1;
      }
      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, &dev->ctxlist, head) {
                  if (pos->handle == ctx->handle) {
                        list_del(&pos->head);
                        drm_free(pos, sizeof(*pos), DRM_MEM_CTXLIST);
                        --dev->ctx_count;
                  }
            }
      }
      mutex_unlock(&dev->ctxlist_mutex);

      return 0;
}

/*@}*/

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