The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 2e2832562c877e6530b8480982d99a4ff90c6777 Mon Sep 17 00:00:00 2001
From: Alan Young consult.awy@gmail.com Date: Fri, 9 Jul 2021 09:48:54 +0100 Subject: [PATCH] ALSA: pcm: Call substream ack() method upon compat mmap commit
If a 32-bit application is being used with a 64-bit kernel and is using the mmap mechanism to write data, then the SNDRV_PCM_IOCTL_SYNC_PTR ioctl results in calling snd_pcm_ioctl_sync_ptr_compat(). Make this use pcm_lib_apply_appl_ptr() so that the substream's ack() method, if defined, is called.
The snd_pcm_sync_ptr() function, used in the 64-bit ioctl case, already uses snd_pcm_ioctl_sync_ptr_compat().
Fixes: 9027c4639ef1 ("ALSA: pcm: Call ack() whenever appl_ptr is updated") Signed-off-by: Alan Young consult.awy@gmail.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/c441f18c-eb2a-3bdd-299a-696ccca2de9c@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 14e32825c339..c88c4316c417 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3063,9 +3063,14 @@ static int snd_pcm_ioctl_sync_ptr_compat(struct snd_pcm_substream *substream, boundary = 0x7fffffff; snd_pcm_stream_lock_irq(substream); /* FIXME: we should consider the boundary for the sync from app */ - if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) - control->appl_ptr = scontrol.appl_ptr; - else + if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) { + err = pcm_lib_apply_appl_ptr(substream, + scontrol.appl_ptr); + if (err < 0) { + snd_pcm_stream_unlock_irq(substream); + return err; + } + } else scontrol.appl_ptr = control->appl_ptr % boundary; if (!(sflags & SNDRV_PCM_SYNC_PTR_AVAIL_MIN)) control->avail_min = scontrol.avail_min;