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
For a fast look-up of a control element via either numid or name
matching (enabled via CONFIG_SND_CTL_FAST_LOOKUP), a locking isn't
needed at all thanks to Xarray. OTOH, the locking is still needed for
a slow linked-list traversal, and that's rather a rare case.
In this patch, we reduce the use of locking at snd_ctl_find_*() API
functions, and switch from controls_rwsem to controls_rwlock for
avoiding unnecessary lock inversions. This also resulted in a nice
cleanup, as *_unlocked() version of snd_ctl_find_*() APIs can be
dropped.
snd_ctl_find_id_mixer_unlocked() is still left just as an alias of
snd_ctl_find_id_mixer(), since soc-card.c has a wrapper and there are
several users. Once after converting there, we can remove it later.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240809104234.8488-3-tiwai@suse.de
We'll re-use the existing rwlock for the protection of control list
lookup, too, and now rename it to a more generic name.
This is a preliminary change, only the rename of the struct field
here, no functional changes.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240809104234.8488-2-tiwai@suse.de
Embedding the ctl_dev in the snd_card object may result in UAF when
the delayed kobj release is used; at the delayed kobj release, it
still accesses the struct device itself while the card memory (that
embeds the struct device) may be already gone.
As a workaround, detach the struct device from the card object by
allocating via the new snd_device_alloc() helper. The rest are just
replacing ctl_dev access to the pointer.
This is based on the fix Curtis posted initially. In this patch, the
changes are split and use the new helper function instead.
Link: https://lore.kernel.org/r/20230801171928.1460120-1-cujomalainey@chromium.org
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Tested-by: Curtis Malainey <cujomalainey@chromium.org>
Link: https://lore.kernel.org/r/20230816160252.23396-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
All callers from other files ignore the return value of this function.
And it can only ever return a non-zero value if the parameter card is NULL.
Move the check for card being NULL into snd_card_free_when_closed() to keep
the previous behaviour. Note this isn't necessary for
snd_card_disconnect_sync() because if card was NULL in there the dereference
of card for dev_err() would oops the kernel. Replace this by an oops
triggered by the dereference of card for spin_lock_irq().
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Geoff Levand <geoff@infradead.org>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230207191907.467756-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Currently the call of kill_fasync() from an interrupt handler might
lead to potential spin deadlocks, as spotted by syzkaller.
Unfortunately, it's not so trivial to fix this lock chain as it's
involved with the tasklist_lock that is touched in allover places.
As a temporary workaround, this patch provides the way to defer the
async signal notification in a work. The new helper functions,
snd_fasync_helper() and snd_kill_faync() are replacements for
fasync_helper() and kill_fasync(), respectively. In addition,
snd_fasync_free() needs to be called at the destructor of the relevant
file object.
Link: https://lore.kernel.org/r/20220728125945.29533-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The control elements are managed in a single linked list and we
traverse the whole list for matching each numid or ctl id per every
inquiry of a control element. This is OK-ish for a small number of
elements but obviously it doesn't scale. Especially the matching with
the ctl id takes time because it checks each field of the snd_ctl_id
element, e.g. the name string is matched with strcmp().
This patch adds the hash tables with Xarray for improving the lookup
speed of a control element. There are two xarray tables added to the
card; one for numid and another for ctl id. For the numid, we use the
numid as the index, while for the ctl id, we calculate a hash key.
The lookup is done via a single xa_load() execution. As long as the
given control element is found on the Xarray table, that's fine, we
can give back a quick lookup result. The problem is when no entry
hits on the table, and for this case, we have a slight optimization.
Namely, the driver checks whether we had a collision on Xarray table,
and do a fallback search (linear lookup of the full entries) only if a
hash key collision happened beforehand.
So, in theory, the inquiry for a non-existing element might take still
time even with this patch in a worst case, but this must be pretty
rare.
The feature is enabled via CONFIG_SND_CTL_FAST_LOOKUP, which is turned
on as default. For simplicity, the option can be turned off only when
CONFIG_EXPERT is set ("You are expert? Then you manage 1000 knobs").
Link: https://lore.kernel.org/r/20211028130027.18764-1-tiwai@suse.de
Link: https://lore.kernel.org/r/20220609180504.775-1-tiwai@suse.de
Link: https://lore.kernel.org/all/cover.1653813866.git.quic_rbankapu@quicinc.com/
Link: https://lore.kernel.org/r/20220610064537.18660-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This is a small helper function to handle the error path more easily
when an error happens during the probe for the device with the
device-managed card. Since devres releases in the reverser order of
the creations, usually snd_card_free() gets called at the last in the
probe error path unless it already reached snd_card_register() calls.
Due to this nature, when a driver expects the resource releases in
card->private_free, this might be called too lately.
As a workaround, one should call the probe like:
static int __some_probe(...) { // do real probe.... }
static int some_probe(...)
{
return snd_card_free_on_error(dev, __some_probe(dev, ...));
}
so that the snd_card_free() is called explicitly at the beginning of
the error path from the probe.
This function will be used in the upcoming fixes to address the
regressions by devres usages.
Fixes: e8ad415b7a ("ALSA: core: Add managed card creation")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220412093141.8008-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
As a second step for preliminary to widen the devres usages among
sound drivers, this patch adds a new ALSA core API function,
snd_devm_card_new(), to create a snd_card object via devres.
When a card object is created by this new function, snd_card_free() is
called automatically and the card object resource gets released at the
device unbinding time.
However, the story isn't that simple. A caveat is that we have to
call snd_card_free() at the very first of the whole resource release
procedure, in order to assure that the all exposed devices on
user-space are deleted and sync with processes accessing those devices
before releasing resources.
For achieving it, snd_card_register() adds a new devres action to
trigger snd_card_free() automatically when the given card object is a
"managed" one. Since usually snd_card_register() is the last step of
the initialization, this should work in most cases.
With all these tricks, some drivers can get rid of the whole driver
remove callback code.
About a bit of implementation details: the patch adds two new flags to
snd_card object: managed and releasing. The former indicates that the
object was created via snd_devm_card_new(), and the latter is used for
avoiding the double-free of snd_card_free() calls. Both flags are
fairly internal and likely uninteresting to normal users.
Link: https://lore.kernel.org/r/20210715075941.23332-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Although the power state check is performed in various places (e.g. at
the entrance of quite a few ioctls), there can be still some pending
tasks that already went into the ioctl handler or other ops, and those
may access the hardware even after the power state check. For
example, kcontrol access ioctl paths that call info/get/put callbacks
may update the hardware registers. If a system wants to assure the
free from such hw access (like the case of PCI rescan feature we're
going to implement in future), this situation must be avoided, and we
have to sync such in-flight tasks finishing beforehand.
For that purpose, this patch introduces a few new things in core code:
- A refcount, power_ref, and a wait queue, power_ref_sleep, to the
card object
- A few new helpers, snd_power_ref(), snd_power_unref(),
snd_power_ref_and_wait(), and snd_power_sync_ref()
In the code paths that call kctl info/read/write/tlv ops, we check the
power state with the newly introduced snd_power_ref_and_wait(). This
function also takes the card.power_ref refcount for tracking this
in-flight task. Once after the access finishes, snd_power_unref() is
called to released the refcount in return. So the driver can sync via
snd_power_sync_ref() assuring that all in-flight tasks have been
finished.
As of this patch, snd_power_sync_ref() is called only at
snd_card_disconnect(), but it'll be used in other places in future.
Note that atomic_t is used for power_ref intentionally instead of
refcount_t. It's because of the design of refcount_t type; refcount_t
cannot be zero-based, and it cannot do dec_and_test() call for
multiple times, hence it's not suitable for our purpose.
Also, this patch changes snd_power_wait() to accept only
SNDRV_CTL_POWER_D0, which is the only value that makes sense.
In later patch, the snd_power_wait() calls will be cleaned up.
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20210523090920.15345-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
ALSA control interface allows users to add arbitrary control elements
(called "user controls" or "user elements"), and its resource usage is
limited just by the max number of control sets (currently 32). This
limit, however, is quite loose: each allocation of control set may
have 1028 elements, and each element may have up to 512 bytes (ILP32) or
1024 bytes (LP64) of value data. Moreover, each control set may contain
the enum strings and TLV data, which can be up to 64kB and 128kB,
respectively. Totally, the whole memory consumption may go over 38MB --
it's quite large, and we'd rather like to reduce the size.
OTOH, there have been other requests even to increase the max number
of user elements; e.g. ALSA firewire stack require the more user
controls, hence we want to raise the bar, too.
For satisfying both requirements, this patch changes the management of
user controls: instead of setting the upper limit of the number of
user controls, we check the actual memory allocation size and set the
upper limit of the total allocation in bytes. As long as the memory
consumption stays below the limit, more user controls are allowed than
the current limit 32. At the same time, we set the lower limit (8MB)
as default than the current theoretical limit, in order to lower the
risk of DoS.
As a compromise for lowering the default limit, now the actual memory
limit is defined as a module option, 'max_user_ctl_alloc_size', so that
user can increase/decrease the limit if really needed, too.
Link: https://lore.kernel.org/r/s5htur3zl5e.wl-tiwai@suse.de
Co-developed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Tested-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210408103149.40357-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This change adds audio jack injection feature through debugfs, with
this feature, we could validate alsa userspace changes by injecting
plugin or plugout events to the non-phantom audio jacks.
With this change, the sound core will build the folders
$debugfs_mount_dir/sound/cardN if SND_DEBUG and DEBUG_FS are enabled.
And if users also enable the SND_JACK_INJECTION_DEBUG, the jack
injection nodes will be built in the folder cardN like below:
$tree $debugfs_mount_dir/sound
$debugfs_mount_dir/sound
├── card0
│ ├── HDMI_DP_pcm_10_Jack
│ │ ├── jackin_inject
│ │ ├── kctl_id
│ │ ├── mask_bits
│ │ ├── status
│ │ ├── sw_inject_enable
│ │ └── type
...
│ └── HDMI_DP_pcm_9_Jack
│ ├── jackin_inject
│ ├── kctl_id
│ ├── mask_bits
│ ├── status
│ ├── sw_inject_enable
│ └── type
└── card1
├── HDMI_DP_pcm_5_Jack
│ ├── jackin_inject
│ ├── kctl_id
│ ├── mask_bits
│ ├── status
│ ├── sw_inject_enable
│ └── type
...
├── Headphone_Jack
│ ├── jackin_inject
│ ├── kctl_id
│ ├── mask_bits
│ ├── status
│ ├── sw_inject_enable
│ └── type
└── Headset_Mic_Jack
├── jackin_inject
├── kctl_id
├── mask_bits
├── status
├── sw_inject_enable
└── type
The nodes kctl_id, mask_bits, status and type are read-only, users
could check jack or jack_kctl's information through them.
The nodes sw_inject_enable and jackin_inject are directly used for
injection. The sw_inject_enable is read-write, users could check if
software injection is enabled or not on this jack, and users could
echo 1 or 0 to enable or disable software injection on this jack. Once
the injection is enabled, the jack will not change by hardware events
anymore, once the injection is disabled, the jack will restore the
last reported hardware events to the jack. The jackin_inject is
write-only, if the injection is enabled, users could echo 1 or 0 to
this node to inject plugin or plugout events to this jack.
For the detailed usage information on these nodes, please refer to
Documentation/sound/designs/jack-injection.rst.
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Link: https://lore.kernel.org/r/20210127085639.74954-2-hui.wang@canonical.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cezary RojewskiandTakashi Iwai
Dr. David Alan GilbertandTakashi Iwai
Ivan OrlovandTakashi Iwai
Oswald BuddenhagenandTakashi Iwai
Uwe Kleine-KönigandTakashi Iwai
Takashi SakamotoandTakashi Iwai
Hui WangandTakashi Iwai
Mauro Carvalho ChehabandTakashi Iwai