From 9780ded39bef5d22a84bdc39112df93f70a58bdd Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 18 Oct 2017 15:51:59 +0200 Subject: ALSA: hda: Avoid racy recreation of widget kobjects The refresh of HD-audio widget sysfs kobjects via snd_hdac_refresh_widget_sysfs() is slightly racy. The driver recreates the whole tree from scratch after deleting the whole. When CONFIG_DEBUG_KOBJECT_RELEASE option is used, kobject release doesn't happen immediately but delayed, while the re-creation of the same named kobject happens soon after invoking kobject_put(). This may end up with the conflicts of duplicated kobjects, as found in the bug report below. In this patch, we take another approach to refresh the tree: instead of recreating the whole tree, just add the new nodes and delete the non-existing nodes. Since the refresh happens only once at initialization, no longer race would happen. Along with the code change, merge snd_hdac_refresh_widget_sysfs() with the existing snd_hdac_refresh_widgets() with an additional bool flag for simplifying the code. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=197307 Signed-off-by: Takashi Iwai --- sound/pci/hda/hda_codec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'sound/pci') diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c index 3db26c451837..bb086665c3e0 100644 --- a/sound/pci/hda/hda_codec.c +++ b/sound/pci/hda/hda_codec.c @@ -977,7 +977,7 @@ int snd_hda_codec_update_widgets(struct hda_codec *codec) hda_nid_t fg; int err; - err = snd_hdac_refresh_widget_sysfs(&codec->core); + err = snd_hdac_refresh_widgets(&codec->core, true); if (err < 0) return err; -- cgit