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SubjectRe: [PATCH] staging: bcm2835-camera: Replace open-coded idr with a struct idr.
Hi Eric,

> Eric Anholt <eric@anholt.net> hat am 11. Mai 2018 um 01:31 geschrieben:
>
>
> We just need some integer handles that can map back to our message
> struct when we're handling a reply, which struct idr is perfect for.
>
> Signed-off-by: Eric Anholt <eric@anholt.net>
> ---
> .../vc04_services/bcm2835-camera/mmal-vchiq.c | 135 ++++--------------
> 1 file changed, 31 insertions(+), 104 deletions(-)
>
> diff --git a/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c b/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
> index 3a3b843fc122..f0dac6440cfb 100644
> --- a/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
> +++ b/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
> @@ -21,7 +21,6 @@
> #include <linux/slab.h>
> #include <linux/completion.h>
> #include <linux/vmalloc.h>
> -#include <linux/btree.h>
> #include <asm/cacheflush.h>
> #include <media/videobuf2-vmalloc.h>
>
> @@ -111,7 +110,11 @@ struct vchiq_mmal_instance;
> /* normal message context */
> struct mmal_msg_context {
> struct vchiq_mmal_instance *instance;
> - u32 handle;
> +
> + /* Index in the context_map idr so that we can find the
> + * mmal_msg_context again when servicing the VCHI reply.
> + */
> + int handle;
>
> union {
> struct {
> @@ -149,13 +152,6 @@ struct mmal_msg_context {
>
> };
>
> -struct vchiq_mmal_context_map {
> - /* ensure serialized access to the btree(contention should be low) */
> - struct mutex lock;
> - struct btree_head32 btree_head;
> - u32 last_handle;
> -};
> -
> struct vchiq_mmal_instance {
> VCHI_SERVICE_HANDLE_T handle;
>
> @@ -165,92 +161,19 @@ struct vchiq_mmal_instance {
> /* vmalloc page to receive scratch bulk xfers into */
> void *bulk_scratch;
>
> - /* mapping table between context handles and mmal_msg_contexts */
> - struct vchiq_mmal_context_map context_map;
> + struct idr context_map;
> + spinlock_t context_map_lock;
>
> /* component to use next */
> int component_idx;
> struct vchiq_mmal_component component[VCHIQ_MMAL_MAX_COMPONENTS];
> };
>
> -static int __must_check
> -mmal_context_map_init(struct vchiq_mmal_context_map *context_map)
> -{
> - mutex_init(&context_map->lock);
> - context_map->last_handle = 0;
> - return btree_init32(&context_map->btree_head);
> -}
> -
> -static void mmal_context_map_destroy(struct vchiq_mmal_context_map *context_map)
> -{
> - mutex_lock(&context_map->lock);
> - btree_destroy32(&context_map->btree_head);
> - mutex_unlock(&context_map->lock);
> -}
> -
> -static u32
> -mmal_context_map_create_handle(struct vchiq_mmal_context_map *context_map,
> - struct mmal_msg_context *msg_context,
> - gfp_t gfp)
> -{
> - u32 handle;
> -
> - mutex_lock(&context_map->lock);
> -
> - while (1) {
> - /* just use a simple count for handles, but do not use 0 */
> - context_map->last_handle++;
> - if (!context_map->last_handle)
> - context_map->last_handle++;
> -
> - handle = context_map->last_handle;
> -
> - /* check if the handle is already in use */
> - if (!btree_lookup32(&context_map->btree_head, handle))
> - break;
> - }
> -
> - if (btree_insert32(&context_map->btree_head, handle,
> - msg_context, gfp)) {
> - /* probably out of memory */
> - mutex_unlock(&context_map->lock);
> - return 0;
> - }
> -
> - mutex_unlock(&context_map->lock);
> - return handle;
> -}
> -
> -static struct mmal_msg_context *
> -mmal_context_map_lookup_handle(struct vchiq_mmal_context_map *context_map,
> - u32 handle)
> -{
> - struct mmal_msg_context *msg_context;
> -
> - if (!handle)
> - return NULL;
> -
> - mutex_lock(&context_map->lock);
> -
> - msg_context = btree_lookup32(&context_map->btree_head, handle);
> -
> - mutex_unlock(&context_map->lock);
> - return msg_context;
> -}
> -
> -static void
> -mmal_context_map_destroy_handle(struct vchiq_mmal_context_map *context_map,
> - u32 handle)
> -{
> - mutex_lock(&context_map->lock);
> - btree_remove32(&context_map->btree_head, handle);
> - mutex_unlock(&context_map->lock);
> -}
> -
> static struct mmal_msg_context *
> get_msg_context(struct vchiq_mmal_instance *instance)
> {
> struct mmal_msg_context *msg_context;
> + int handle;
>
> /* todo: should this be allocated from a pool to avoid kzalloc */
> msg_context = kzalloc(sizeof(*msg_context), GFP_KERNEL);
> @@ -258,32 +181,40 @@ get_msg_context(struct vchiq_mmal_instance *instance)
> if (!msg_context)
> return ERR_PTR(-ENOMEM);
>
> - msg_context->instance = instance;
> - msg_context->handle =
> - mmal_context_map_create_handle(&instance->context_map,
> - msg_context,
> - GFP_KERNEL);
> + /* Create an ID that will be passed along with our message so
> + * that when we service the VCHI reply, we can look up what
> + * message is being replied to.
> + */
> + spin_lock(&instance->context_map_lock);
> + handle = idr_alloc(&instance->context_map, msg_context,
> + 0, 0, GFP_KERNEL);
> + spin_unlock(&instance->context_map_lock);
>
> - if (!msg_context->handle) {
> + if (msg_context->handle < 0) {

handle < 0 ?

> kfree(msg_context);
> - return ERR_PTR(-ENOMEM);
> + return ERR_PTR(handle);
> }
>
> + msg_context->instance = instance;
> + msg_context->handle = handle;
> +
> return msg_context;
> }
>

Regards
Stefan

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