linux/include
Cezary Rojewski 84446536f6 ALSA: control: Verify put() result when in debug mode
The put() operation is expected to return:
1) 0 on success if no changes were made
2) 1 on success if changes were made
3) error code otherwise

Currently 2) is usually ignored when writing control-operations. While
forcing compliance is not an option right now, make it easier for
developers to adhere to the expectations and notice problems by logging
them when CONFIG_SND_CTL_DEBUG is enabled.

Due to large size of struct snd_ctl_elem_value, 'value_buf' is provided
as a reusable buffer for kctl->put() verification. This prevents
exhausting the stack when verifying the operation.

>From user perspective, patch introduces a new trace/events category
'snd_ctl' containing a single 'snd_ctl_put' event type. Log sample:

  amixer-1086    [003] .....    8.035939: snd_ctl_put: success: expected=0, actual=0 for ctl numid=1, iface=MIXER, name='Master Playback Volume', index=0, device=0, subdevice=0, card=0
  amixer-1087    [003] .....    8.938721: snd_ctl_put: success: expected=1, actual=1 for ctl numid=1, iface=MIXER, name='Master Playback Volume', index=0, device=0, subdevice=0, card=0
  amixer-1088    [003] .....    9.631470: snd_ctl_put: success: expected=1, actual=1 for ctl numid=1, iface=MIXER, name='Master Playback Volume', index=0, device=0, subdevice=0, card=0
  amixer-1089    [000] .....    9.636786: snd_ctl_put: fail: expected=1, actual=0 for ctl numid=5, iface=MIXER, name='Loopback Mute', index=0, device=0, subdevice=0, card=0

Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260224205619.584795-1-cezary.rojewski@intel.com
2026-02-28 09:32:39 +01:00
..
acpi mailbox: platform and core updates 2026-02-14 11:13:32 -08:00
asm-generic hyperv-next for v7.0 2026-02-20 08:48:31 -08:00
clocksource
crypto Networking changes for 7.0 2026-02-11 19:31:52 -08:00
cxl
drm drm/pagemap: pass pagemap_addr by reference 2026-02-17 19:39:44 -05:00
dt-bindings phy-for-7.0 2026-02-17 11:40:04 -08:00
hyperv hyperv-next for v7.0 2026-02-20 08:48:31 -08:00
keys
kunit treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
kvm
linux fsverity fixes for v7.0-rc1 2026-02-22 13:12:04 -08:00
math-emu
media [GIT PULL for v7.0] media updates 2026-02-11 12:20:25 -08:00
memory
misc
net Convert more 'alloc_obj' cases to default GFP_KERNEL arguments 2026-02-21 20:03:00 -08:00
pcmcia
ras
rdma RDMA v7.0 merge window 2026-02-12 17:05:20 -08:00
rv rv: Fix multiple definition of __pcpu_unique_da_mon_this 2026-02-20 13:12:00 +01:00
scsi SCSI misc on 20260212 2026-02-12 15:43:02 -08:00
soc
sound ALSA: control: Verify put() result when in debug mode 2026-02-28 09:32:39 +01:00
target
trace vfs-7.0-rc1.misc.2 2026-02-16 13:00:36 -08:00
uapi drm next fixes for 7.0-rc1 2026-02-20 15:36:38 -08:00
ufs
vdso
video
xen
Kbuild