Commit c4a8828d authored by Mike Isely's avatar Mike Isely Committed by Mauro Carvalho Chehab
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V4L/DVB (7319): pvrusb2: Close potential race condition during initialization 



There is a callback that is issued to into pvr2_context from pvr2_hdw
after initialization is done.  There was a probability that this
callback could get missed.  Fixed.

Signed-off-by: default avatarMike Isely <isely@pobox.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
parent ee9ca4b2

drivers/media/video/pvrusb2/pvrusb2-context.c

+3 −4
Original line number Diff line number Diff line
@@ -75,10 +75,9 @@ struct pvr2_context *pvr2_context_create( 
		mp = NULL;

		goto done;

	}

	pvr2_hdw_set_state_callback(mp->hdw,

	pvr2_hdw_initialize(mp->hdw,

			    (void (*)(void *))pvr2_context_state_check,

			    mp);

	pvr2_context_state_check(mp);

 done:

	return mp;

}

drivers/media/video/pvrusb2/pvrusb2-hdw.c

+17 −14
Original line number Diff line number Diff line
@@ -1813,8 +1813,23 @@ static void pvr2_hdw_setup(struct pvr2_hdw *hdw) 
}





/* Create and return a structure for interacting with the underlying

   hardware */

/* Perform second stage initialization.  Set callback pointer first so that

   we can avoid a possible initialization race (if the kernel thread runs

   before the callback has been set). */

void pvr2_hdw_initialize(struct pvr2_hdw *hdw,

			 void (*callback_func)(void *),

			 void *callback_data)

{

	LOCK_TAKE(hdw->big_lock); do {

		hdw->state_data = callback_data;

		hdw->state_func = callback_func;

	} while (0); LOCK_GIVE(hdw->big_lock);

	queue_work(hdw->workqueue,&hdw->workinit);

}





/* Create, set up, and return a structure for interacting with the

   underlying hardware.  */

struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf,

				 const struct usb_device_id *devid)

{
@@ -2039,7 +2054,6 @@ struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf, 
	mutex_init(&hdw->ctl_lock_mutex);

	mutex_init(&hdw->big_lock_mutex);



	queue_work(hdw->workqueue,&hdw->workinit);

	return hdw;

 fail:

	if (hdw) {
@@ -2521,17 +2535,6 @@ static int pvr2_hdw_wait(struct pvr2_hdw *hdw,int state) 
}





void pvr2_hdw_set_state_callback(struct pvr2_hdw *hdw,

				 void (*callback_func)(void *),

				 void *callback_data)

{

	LOCK_TAKE(hdw->big_lock); do {

		hdw->state_data = callback_data;

		hdw->state_func = callback_func;

	} while (0); LOCK_GIVE(hdw->big_lock);

}





/* Return name for this driver instance */

const char *pvr2_hdw_get_driver_name(struct pvr2_hdw *hdw)

{

drivers/media/video/pvrusb2/pvrusb2-hdw.h

+6 −5
Original line number Diff line number Diff line
@@ -101,14 +101,15 @@ struct pvr2_hdw; 
struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf,

				 const struct usb_device_id *devid);



/* Destroy hardware interaction structure */

void pvr2_hdw_destroy(struct pvr2_hdw *);



/* Register a function to be called whenever the master state changes. */

void pvr2_hdw_set_state_callback(struct pvr2_hdw *,

/* Perform second stage initialization, passing in a notification callback

   for when the master state changes. */

void pvr2_hdw_initialize(struct pvr2_hdw *,

			 void (*callback_func)(void *),

			 void *callback_data);



/* Destroy hardware interaction structure */

void pvr2_hdw_destroy(struct pvr2_hdw *);



/* Return true if in the ready (normal) state */

int pvr2_hdw_dev_ok(struct pvr2_hdw *);