dect/linux-2.6
Archived
14
0
Fork 0
Code Releases Activity

V4L/DVB: IR: replace workqueue with kthread

Browse source 
It is perfectly possible to have ir_raw_event_work
running concurently on two cpus, thus we must protect
it from that situation.

This stems from the fact that if hardware sends short packets of samples
we might end up queueing the work item more times that nessesary.

Such job isn't well suited for a workqueue, so use a kernel thread.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Maxim Levitsky 2010-07-31 11:59:17 -03:00 committed by Mauro Carvalho Chehab
parent 45a568fa6f
commit 0d2cb1de8e
2 changed files with 32 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
drivers/media/IR/ir-core-priv.h
View file

@ -32,7 +32,7 @@ struct ir_raw_handler {
struct ir_raw_event_ctrl {
struct list_head list; /* to keep track of raw clients */
struct work_struct rx_work; /* for the rx decoding workqueue */
struct task_struct *thread;
struct kfifo kfifo; /* fifo for the pulse/space durations */
ktime_t last_event; /* when last event occurred */
enum raw_event_type last_type; /* last event type */

42
drivers/media/IR/ir-raw-event.c
View file

@ -12,9 +12,10 @@
* GNU General Public License for more details.
*/
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/freezer.h>
#include "ir-core-priv.h"
/* Define the max number of pulse/space transitions to buffer */
@ -33,20 +34,30 @@ static u64 available_protocols;
static struct work_struct wq_load;
#endif
static void ir_raw_event_work(struct work_struct *work)
static int ir_raw_event_thread(void *data)
{
struct ir_raw_event ev;
struct ir_raw_handler *handler;
struct ir_raw_event_ctrl *raw =
container_of(work, struct ir_raw_event_ctrl, rx_work);
struct ir_raw_event_ctrl *raw = (struct ir_raw_event_ctrl *)data;
while (!kthread_should_stop()) {
try_to_freeze();
while (kfifo_out(&raw->kfifo, &ev, sizeof(ev)) == sizeof(ev)) {
mutex_lock(&ir_raw_handler_lock);
list_for_each_entry(handler, &ir_raw_handler_list, list)
handler->decode(raw->input_dev, ev);
while (kfifo_out(&raw->kfifo, &ev, sizeof(ev)) == sizeof(ev)) {
list_for_each_entry(handler, &ir_raw_handler_list, list)
handler->decode(raw->input_dev, ev);
raw->prev_ev = ev;
}
mutex_unlock(&ir_raw_handler_lock);
raw->prev_ev = ev;
set_current_state(TASK_INTERRUPTIBLE);
schedule();
}
return 0;
}
/**
@ -141,7 +152,7 @@ void ir_raw_event_handle(struct input_dev *input_dev)
if (!ir->raw)
return;
schedule_work(&ir->raw->rx_work);
wake_up_process(ir->raw->thread);
}
EXPORT_SYMBOL_GPL(ir_raw_event_handle);
@ -170,7 +181,7 @@ int ir_raw_event_register(struct input_dev *input_dev)
return -ENOMEM;
ir->raw->input_dev = input_dev;
INIT_WORK(&ir->raw->rx_work, ir_raw_event_work);
ir->raw->enabled_protocols = ~0;
rc = kfifo_alloc(&ir->raw->kfifo, sizeof(s64) * MAX_IR_EVENT_SIZE,
GFP_KERNEL);
@ -180,6 +191,15 @@ int ir_raw_event_register(struct input_dev *input_dev)
return rc;
}
ir->raw->thread = kthread_run(ir_raw_event_thread, ir->raw,
"rc%u", (unsigned int)ir->devno);
if (IS_ERR(ir->raw->thread)) {
kfree(ir->raw);
ir->raw = NULL;
return PTR_ERR(ir->raw->thread);
}
mutex_lock(&ir_raw_handler_lock);
list_add_tail(&ir->raw->list, &ir_raw_client_list);
list_for_each_entry(handler, &ir_raw_handler_list, list)
@ -198,7 +218,7 @@ void ir_raw_event_unregister(struct input_dev *input_dev)
if (!ir->raw)
return;
cancel_work_sync(&ir->raw->rx_work);
kthread_stop(ir->raw->thread);
mutex_lock(&ir_raw_handler_lock);
list_del(&ir->raw->list);