Re: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U6

[Adam Heath]

On Tue, 19 Oct 2004, Ingo Molnar wrote:

>
> * Adam Heath <doogie@xxxxxxxxxx> wrote:
>
> > I am still having the same bug(repeatable by running liquidwar) as I
> > reported with -U5(see my earlier email).
>
> ok, this seems to be some questionable code in OSS. It really has no
> business up()-ing the inode semaphore - nobody down()-ed it before! This
> could be either a bad workaround for a bug/hang someone saw, or an old
> VFS assumption that doesnt hold anymore. In any case, could you try the
> patch below, does it fix liquidwar?

Yup, the below fixes it.  However, this problem *only* started occuring in
-U5.  I've been running liquidwar on all versions(it's my current
game-to-play-when-I-feel-stupid program).

>
> 	Ingo
>
> --- linux/sound/core/oss/pcm_oss.c.orig
> +++ linux/sound/core/oss/pcm_oss.c
> @@ -2120,9 +2120,7 @@ static ssize_t snd_pcm_oss_write(struct
>  	substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
>  	if (substream == NULL)
>  		return -ENXIO;
> -	up(&file->f_dentry->d_inode->i_sem);
>  	result = snd_pcm_oss_write1(substream, buf, count);
> -	down(&file->f_dentry->d_inode->i_sem);
>  #ifdef OSS_DEBUG
>  	printk("pcm_oss: write %li bytes (wrote %li bytes)\n", (long)count, (long)result);
>  #endif
> -
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