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media: media-request: add media_request_(un)lock_for_access

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Add helper functions to prevent a completed request from being
re-inited while it is being accessed.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Hans Verkuil
2018-08-27 11:10:38 -04:00
committed by Mauro Carvalho Chehab
parent e5079cf113
commit 6736f4e948
2 changed files with 66 additions and 0 deletions
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56
include/media/media-request.h
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@@ -53,6 +53,7 @@ struct media_request_object;
* @debug_str: Prefix for debug messages (process name:fd)
* @state: The state of the request
* @updating_count: count the number of request updates that are in progress
* @access_count: count the number of request accesses that are in progress
* @objects: List of @struct media_request_object request objects
* @num_incomplete_objects: The number of incomplete objects in the request
* @poll_wait: Wait queue for poll
@@ -64,6 +65,7 @@ struct media_request {
char debug_str[TASK_COMM_LEN + 11];
enum media_request_state state;
unsigned int updating_count;
unsigned int access_count;
struct list_head objects;
unsigned int num_incomplete_objects;
struct wait_queue_head poll_wait;
@@ -72,6 +74,50 @@ struct media_request {
#ifdef CONFIG_MEDIA_CONTROLLER
/**
* media_request_lock_for_access - Lock the request to access its objects
*
* @req: The media request
*
* Use before accessing a completed request. A reference to the request must
* be held during the access. This usually takes place automatically through
* a file handle. Use @media_request_unlock_for_access when done.
*/
static inline int __must_check
media_request_lock_for_access(struct media_request *req)
{
unsigned long flags;
int ret = -EBUSY;
spin_lock_irqsave(&req->lock, flags);
if (req->state == MEDIA_REQUEST_STATE_COMPLETE) {
req->access_count++;
ret = 0;
}
spin_unlock_irqrestore(&req->lock, flags);
return ret;
}
/**
* media_request_unlock_for_access - Unlock a request previously locked for
* access
*
* @req: The media request
*
* Unlock a request that has previously been locked using
* @media_request_lock_for_access.
*/
static inline void media_request_unlock_for_access(struct media_request *req)
{
unsigned long flags;
spin_lock_irqsave(&req->lock, flags);
if (!WARN_ON(!req->access_count))
req->access_count--;
spin_unlock_irqrestore(&req->lock, flags);
}
/**
* media_request_lock_for_update - Lock the request for updating its objects
*
@@ -333,6 +379,16 @@ void media_request_object_complete(struct media_request_object *obj);
#else
static inline int __must_check
media_request_lock_for_access(struct media_request *req)
{
return -EINVAL;
}
static inline void media_request_unlock_for_access(struct media_request *req)
{
}
static inline int __must_check
media_request_lock_for_update(struct media_request *req)
{