From c4a8828ddbf5fb445d2679ab006d5743540fc41a Mon Sep 17 00:00:00 2001 From: Mike Isely Date: Tue, 22 Apr 2008 14:45:44 -0300 Subject: [PATCH] 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: Mike Isely Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/pvrusb2/pvrusb2-context.c | 7 ++--- drivers/media/video/pvrusb2/pvrusb2-hdw.c | 31 ++++++++++--------- drivers/media/video/pvrusb2/pvrusb2-hdw.h | 11 ++++--- 3 files changed, 26 insertions(+), 23 deletions(-) diff --git a/drivers/media/video/pvrusb2/pvrusb2-context.c b/drivers/media/video/pvrusb2/pvrusb2-context.c index 2a6726e403..953784c08a 100644 --- a/drivers/media/video/pvrusb2/pvrusb2-context.c +++ b/drivers/media/video/pvrusb2/pvrusb2-context.c @@ -75,10 +75,9 @@ struct pvr2_context *pvr2_context_create( mp = NULL; goto done; } - pvr2_hdw_set_state_callback(mp->hdw, - (void (*)(void *))pvr2_context_state_check, - mp); - pvr2_context_state_check(mp); + pvr2_hdw_initialize(mp->hdw, + (void (*)(void *))pvr2_context_state_check, + mp); done: return mp; } diff --git a/drivers/media/video/pvrusb2/pvrusb2-hdw.c b/drivers/media/video/pvrusb2/pvrusb2-hdw.c index c51c5cef82..f2d2677936 100644 --- a/drivers/media/video/pvrusb2/pvrusb2-hdw.c +++ b/drivers/media/video/pvrusb2/pvrusb2-hdw.c @@ -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) { diff --git a/drivers/media/video/pvrusb2/pvrusb2-hdw.h b/drivers/media/video/pvrusb2/pvrusb2-hdw.h index 57e1ff4914..597ee50331 100644 --- a/drivers/media/video/pvrusb2/pvrusb2-hdw.h +++ b/drivers/media/video/pvrusb2/pvrusb2-hdw.h @@ -101,14 +101,15 @@ struct pvr2_hdw; struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf, const struct usb_device_id *devid); +/* 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 *); -/* Register a function to be called whenever the master state changes. */ -void pvr2_hdw_set_state_callback(struct pvr2_hdw *, - void (*callback_func)(void *), - void *callback_data); - /* Return true if in the ready (normal) state */ int pvr2_hdw_dev_ok(struct pvr2_hdw *); -- 2.39.5