On Tue, 26 Mar 2019 08:49:33 +0100, <twischer@xxxxxxxxxxxxxx> wrote: > > From: Timo Wischer <twischer@xxxxxxxxxxxxxx> > > snd_pcm_link() can be called by the user as long as the device is not > yet started. Therefore currently a driver which wants to iterate over > the linked substreams has to do this at the start trigger. But the start > trigger should not block for a long time. Therefore there is no callback > which can be used to iterate over the linked substreams without delaying > the start trigger. > This patch introduces a new callback function which will be called after > the linked substream list was updated by snd_pcm_link(). This callback > function is allowed to block for a longer time without interfering the > synchronized start up of linked substreams. > > Signed-off-by: Timo Wischer <twischer@xxxxxxxxxxxxxx> Well, the idea appears interesting, but I'm afraid that the implementation is still racy. The place you're calling the new callback isn't protected, hence the stream can be triggered while calling it. That is, even during operating your loopback link_changed callback, another thread is able to start the stream. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
