Am Donnerstag, 5. Oktober 2006 16:13 schrieb Takashi Iwai:
> At Thu, 5 Oct 2006 15:54:47 +0200,
> Karsten Wiese wrote:
> >
> > snd_disconnected_file, virtual device
> >
> > On response to "usb disconnect" an usb-soundcard manipulates
> > that snd_card's file's f_ops to only allow release
> > by calling this virtual device's
> > void snd_disconnect_file(struct file *file).
> > After release is actually called, the virtual device instance is freed.
> >
> > Signed-off-by: Karsten Wiese <fzu@xxxxxxxxxxxxxxxxxxxxx>
>
> Thanks, the code looks better.
>
> > +void snd_disconnect_file(struct file *file)
> > +{
> > + struct snd_disconnected_file *df;
> > + df = kmalloc(sizeof(struct snd_disconnected_file), GFP_KERNEL);
> > + if (df == NULL)
> > + panic("Atomic allocation failed for snd_disconnected_file!");
>
> The message doesn't match...
> Some people prefer "if (!df)" although I myself don't mind at all.
Me neither. I remember Al Viro preferring the "== NULL".
>
> > +
> > + df->file = file;
> > + df->f_op = file->f_op;
> > +
> > + mutex_lock(&mutex);
> > + list_add(&df->list, &disconnected_files);
> > + mutex_unlock(&mutex);
> > +
> > + fops_get(&snd_disconnect_f_ops);
> > + file->f_op = &snd_disconnect_f_ops;
> > + printk(KERN_INFO "%s rc3\n", __FUNCTION__);
>
> This will be removed in the final version, right?
right.
>
> > +}
>
> My only concern is whether the release of the old f_op can be called
> at the same time during snd_disconnect_file(). If this can happen,
> it's racy and results in a memory leak.
Uiuiui, good point!
rc4 will merge with init.c.
Karsten
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