[PATCH] DVB: dvb_frontend: fix delayed thread exit

[Andreas Oberritter <obi@linuxtv.org>]

On 10.12.2011 00:43, Mauro Carvalho Chehab wrote:
> On 09-12-2011 21:37, Mauro Carvalho Chehab wrote:
>> On 09-12-2011 20:33, Devin Heitmueller wrote:
>>> On Fri, Dec 9, 2011 at 5:11 PM, Mauro Carvalho Chehab
>>> <mchehab@redhat.com> wrote:
>>>>> Could someone explain reason for that?
>>>>
>>>>
>>>> I dunno, but I think this needs to be fixed, at least when the frontend
>>>> is opened with O_NONBLOCK.
>>>
>>> Are you doing the drx-k firmware load on dvb_init()? That could
>>> easily take 4 seconds.
>>
>> No. The firmware were opened previously.
> 
> Maybe the delay is due to this part of dvb_frontend.c:
> 
> static int dvb_mfe_wait_time = 5;
> ...
>                         int mferetry = (dvb_mfe_wait_time << 1);
> 
>                         mutex_unlock (&adapter->mfe_lock);
>                         while (mferetry-- && (mfedev->users != -1 ||
>                                         mfepriv->thread != NULL)) {
>                                 if(msleep_interruptible(500)) {
>                                         if(signal_pending(current))
>                                                 return -EINTR;
>                                 }
>                         }

I haven't looked at the mfe code, but in case it's waiting for the
frontend thread to exit, there's a problem that causes the thread
not to exit immediately. Here's a patch that's been sitting in my
queue for a while:

---

Signed-off-by: Andreas Oberritter <obi@linuxtv.org>

diff --git a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c b/linux/drivers/media/dvb/dvb-core/dvb_frontend.c
index 7784d74..6823c2b 100644
--- a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c	2011-09-07 12:32:24.000000000 +0200
+++ a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c	2011-09-13 15:55:48.865742791 +0200
@@ -514,7 +514,7 @@
 		return 1;
 
 	if (fepriv->dvbdev->writers == 1)
-		if (time_after(jiffies, fepriv->release_jiffies +
+		if (time_after_eq(jiffies, fepriv->release_jiffies +
 				  dvb_shutdown_timeout * HZ))
 			return 1;
 
@@ -2070,12 +2070,15 @@
 
 	dprintk ("%s\n", __func__);
 
-	if ((file->f_flags & O_ACCMODE) != O_RDONLY)
+	if ((file->f_flags & O_ACCMODE) != O_RDONLY) {
 		fepriv->release_jiffies = jiffies;
+		mb();
+	}
 
 	ret = dvb_generic_release (inode, file);
 
 	if (dvbdev->users == -1) {
+		wake_up(&fepriv->wait_queue);
 		if (fepriv->exit != DVB_FE_NO_EXIT) {
 			fops_put(file->f_op);
 			file->f_op = NULL;