Takashi Iwai [Wed, 28 Jun 2017 06:13:41 +0000 (08:13 +0200)]
ALSA: Fix forgotten dependency fix for tristate OSS sequencer kconfig
In the commit 3d774d5ef066 ("ALSA: seq: Allow the tristate build of
OSS emulation") we changed CONFIG_SND_SEQUENCER_OSS to tristate, but a
couple of places were forgotten, namely, opl3 and emux Makefile.
These contain the line like
snd-opl3-synth-$(CONFIG_SND_SEQUENCER_OSS) += opl3_oss.o
and this doesn't work any longer as expected because snd-opl3-synth
can be built-in while CONFIG_SND_SEQUENCER_OSS=m.
This patch fixes these places to build properly for the new kconfig
dependency. In the end, we had to use ifneq() to satisfy the
requirement. It's a bit ugly, but lesser evil.
Fixes: 3d774d5ef066 ("ALSA: seq: Allow the tristate build of OSS emulation") Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Iwai [Tue, 27 Jun 2017 09:54:37 +0000 (11:54 +0200)]
ALSA: pcm: Disable only control mmap for explicit appl_ptr sync
Now that user-space (typically alsa-lib) can specify which protocol
version it supports, we can optimize the kernel code depending on the
reported protocol version.
In this patch, we change the previous hack for enforcing the appl_ptr
sync by disabling status/control mmap. Instead of forcibly disabling
both mmaps, we disable only the control mmap when user-space declares
the supported protocol version new enough. For older user-space,
still both PCM status and control mmaps are disabled when requested by
the driver due to the compatibility reason.
Takashi Iwai [Mon, 19 Jun 2017 21:11:54 +0000 (23:11 +0200)]
ALSA: pcm: Add an ioctl to specify the supported protocol version
We have an ioctl to inform the PCM protocol version the running kernel
supports, but there is no way to know which protocol version the
user-space can understand. This lack of information caused headaches
in the past when we tried to extend the ABI. For example, because we
couldn't guarantee the validity of the reserved bytes, we had to
introduce a new ioctl SNDRV_PCM_IOCTL_STATUS_EXT for assigning a few
new fields in the formerly reserved bits. If we could know that it's
a new alsa-lib, we could assume the availability of the new fields,
thus we could have reused the existing SNDRV_PCM_IOCTL_STATUS.
In order to improve the ABI extensibility, this patch adds a new ioctl
for user-space to inform its supporting protocol version to the
kernel. By reporting the supported protocol from user-space, the
kernel can judge which feature should be provided and which not.
With the addition of the new ioctl, the PCM protocol version is bumped
to 2.0.14, too. User-space checks the kernel protocol version via
SNDRV_PCM_INFO_PVERSION, then it sets the supported version back via
SNDRV_PCM_INFO_USER_PVERSION.
Hui Wang [Mon, 26 Jun 2017 04:30:32 +0000 (12:30 +0800)]
ALSA: hda/realtek - There is no loopback mixer in the ALC234/274/294
We have a Lenovo machine with the codec ALC294 on it, without the
patch, the Node 0x0b is regarded as the loopback mixer, but the Node
0x0b in this codec is "Vendor Defined Widget" instead of the audio
mixer, please see the log below:
Takashi Iwai [Mon, 19 Jun 2017 20:39:18 +0000 (22:39 +0200)]
ALSA: pcm: Add the explicit appl_ptr sync support
Currently x86 platforms use the PCM status/control mmaps for
transferring the PCM status and appl_ptr between kernel and
user-spaces. The mmap is a most efficient way of communication, but
it has a drawback per its nature, namely, it can't notify the change
explicitly to kernel.
The lack of appl_ptr update notification is a problem on a few
existing drivers, but it's mostly a small issue and negligible.
However, a new type of driver that uses DSP for a deep buffer
management requires the exact position of appl_ptr for calculating the
buffer prefetch size, and the asynchronous appl_ptr update between
kernel and user-spaces becomes a significant problem for it.
How can we enforce user-space to report the appl_ptr update? The way
is relatively simple. Just by disabling the PCM control mmap, the
user-space is supposed to fall back to the mode using SYNC_PTR ioctl,
and the kernel gets control over that. This fallback mode is used in
all non-x86 platforms as default, and also in the 32bit compatible
model on all platforms including x86. It's been implemented already
over a decade, so we can say it's fairly safe and stably working.
With the help of the knowledge above, this patch introduces a new PCM
info flag SNDRV_PCM_INFO_SYNC_APPLPTR for achieving the appl_ptr sync
from user-space. When a driver sets this flag at open, the PCM status
/ control mmap is disabled, which effectively switches to SYNC_PTR
mode in user-space side.
In this version, both PCM status and control mmaps are disabled
although only the latter, control mmap, is the target. It's because
the current alsa-lib implementation supposes that both status and
control mmaps are always coupled, thus it handles a fatal error when
only one of them fails.
Of course, the disablement of the status/control mmaps may bring a
slight performance overhead. Thus, as of now, this should be used
only for the dedicated devices that deserves.
Note that the disablement of mmap is a sort of workaround. In the
later patch, we'll introduce the way to identify the protocol version
alsa-lib supports, and keep mmap working while the sync_ptr is
performed together.
Kailang Yang [Wed, 21 Jun 2017 06:50:54 +0000 (14:50 +0800)]
ALSA: hda/realtek - Add default procedure for suspend and resume state
Except ALC269.
This will reduce pop noise from headset or headphone.
If codec enter to power save state, when plug headset or headphone....
It has a chance to cut off power by system.
Our new codec use this procedure will be more stable during suspend
and resume state.
Signed-off-by: Kailang Yang <kailang@realtek.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Iwai [Fri, 16 Jun 2017 20:29:55 +0000 (22:29 +0200)]
ALSA: pcm: Fix possible inconsistent appl_ptr update via mmap
The ALSA PCM core refers to the appl_ptr value stored on the mmapped
page that is shared between kernel and user-space. Although the
reference is performed in the PCM stream lock, it doesn't guarantee
the atomic access when the value gets updated concurrently from the
user-space on another CPU.
In most of codes, this is no big problem, but still there are a few
places that may result in slight inconsistencies because they access
runtime->control->appl_ptr multiple times; that is, the second read
might be a different value from the first value. It can be even
backward or jumping, as we have no control for it. Hence, the
calculation may give an unexpected value. Luckily, there is no
security vulnerability by that, as far as I've checked. But still we
should address it.
This patch tries to reduce such possible cases. The fix is simple --
we just read once, store it to a local variable and use it for the
rest calculations. The READ_ONCE() macro is used for it in order to
avoid the ill-effect by possible compiler optimizations.
Takashi Iwai [Mon, 19 Jun 2017 15:49:48 +0000 (17:49 +0200)]
ALSA: hda: Fix potential race at unregistration and unsol events
When the codec device is unregistered / freed, it may release the
resource while being used in an unsolicited event like the jack
detection work. This leads to use-after-free.
The fix here is to unregister the device at first, i.e. removing the
codec from the list, then flushing the pending works to assure that
all unsol events are gone. After this point, we're free from
accessing the codec via unsol events, thus can release the resources
gracefully.
The issue was spotted originally by Intel CI, but it couldn't be
reproduced reliably by its nature. So let's hope this fix really
addresses the whole issues.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196045 Reported-by: Martin Peres <martin.peres@free.fr> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Iwai [Wed, 14 Jun 2017 05:26:00 +0000 (07:26 +0200)]
ALSA: hda - Add AZX_DRIVER_SKL for simplification
We checked the quirks specific to the recent Intel chips by checking
the PCI IDs manually, but it's becoming messy with lots of IS_SKL()
and other macros, as the amount accumulated.
For simplification, here the new AZX_DRIVER_SKL type is introduced,
and check chip->driver_type instead of the manual PCI ID. The short
name for this is still "HDA Intel PCH", so that it doesn't break the
existing user-space unnecessarily.
Takashi Iwai [Wed, 14 Jun 2017 05:37:14 +0000 (07:37 +0200)]
ALSA: hda - Apply quirks to Broxton-T, too
Broxton-T was a forgotten child and we didn't apply the quirks for
Skylake+ properly. Meanwhile, a quirk for reducing the DMA latency
seems specific to the early Broxton model, so we leave as is.
ALSA: line6: remove unnecessary initialization to PODHD500X
Remove Initialization from POD HD500X because it's not needed.
Every time the device is connected dmesg gives the following output:
"receive length failed (error -11)".
To solve this problem, another flags is introduced
(LINE6_CAP_CONTROL_INFO) and it is only used for PODX3 in: sysfs
entries, call podhd_startup_finalize(pod) and disconnection.
With this patch the error disappear.
Signed-off-by: Hans P. Moller <hmoller@uc.cl> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Sakamoto [Sun, 11 Jun 2017 07:08:21 +0000 (16:08 +0900)]
ALSA: firewire-lib: Fix stall of process context at packet error
At Linux v3.5, packet processing can be done in process context of ALSA
PCM application as well as software IRQ context for OHCI 1394. Below is
an example of the callgraph (some calls are omitted).
ioctl(2) with e.g. HWSYNC
(sound/core/pcm_native.c)
->snd_pcm_common_ioctl1()
->snd_pcm_hwsync()
->snd_pcm_stream_lock_irq
(sound/core/pcm_lib.c)
->snd_pcm_update_hw_ptr()
->snd_pcm_udpate_hw_ptr0()
->struct snd_pcm_ops.pointer()
(sound/firewire/*)
= Each handler on drivers in ALSA firewire stack
(sound/firewire/amdtp-stream.c)
->amdtp_stream_pcm_pointer()
(drivers/firewire/core-iso.c)
->fw_iso_context_flush_completions()
->struct fw_card_driver.flush_iso_completion()
(drivers/firewire/ohci.c)
= flush_iso_completions()
->struct fw_iso_context.callback.sc
(sound/firewire/amdtp-stream.c)
= in_stream_callback() or out_stream_callback()
->...
->snd_pcm_stream_unlock_irq
When packet queueing error occurs or detecting invalid packets in
'in_stream_callback()' or 'out_stream_callback()', 'snd_pcm_stop_xrun()'
is called on local CPU with disabled IRQ.
(sound/firewire/amdtp-stream.c)
in_stream_callback() or out_stream_callback()
->amdtp_stream_pcm_abort()
->snd_pcm_stop_xrun()
->snd_pcm_stream_lock_irqsave()
->snd_pcm_stop()
->snd_pcm_stream_unlock_irqrestore()
The process is stalled on the CPU due to attempt to acquire recursive lock.
This commit fixes the above bug. This assumes two cases:
1. Any error is detected in software IRQ context of OHCI 1394 context.
In this case, PCM substream should be aborted in packet handler. On the
other hand, it should not be done in any process context. TO distinguish
these two context, use 'in_interrupt()' macro.
2. Any error is detect in process context of ALSA PCM application.
In this case, PCM substream should not be aborted in packet handler
because PCM substream lock is acquired. The task to abort PCM substream
should be done in ALSA PCM core. For this purpose, SNDRV_PCM_POS_XRUN is
returned at 'struct snd_pcm_ops.pointer()'.
Takashi Iwai [Wed, 14 Jun 2017 14:20:32 +0000 (16:20 +0200)]
ALSA: pcm: Don't treat NULL chmap as a fatal error
The standard PCM chmap helper callbacks treat the NULL info->chmap as
a fatal error and spews the kernel warning with stack trace when
CONFIG_SND_DEBUG is on. This was OK, originally it was supposed to be
always static and non-NULL. But, as the recent addition of Intel LPE
audio driver shows, the chmap content may vary dynamically, and it can
be even NULL when disconnected. The user still sees the kernel
warning unnecessarily.
For clearing such a confusion, this patch simply removes the
snd_BUG_ON() in each place, just returns an error without warning.
Drivers can implement 'struct snd_pcm_ops.ioctl' to handle some requests
from ALSA PCM core. These requests are internal purpose in kernel land.
Usually common set of operations are used for it.
SNDRV_PCM_IOCTL1_INFO is one of the requests. According to code comment,
it has been obsoleted in the old days.
We can see old releases in ftp.alsa-project.org. The command was firstly
introduced in v0.5.0 release as SND_PCM_IOCTL1_INFO, to allow drivers to
fill data of 'struct snd_pcm_channel_info' type. In v0.9.0 release,
this was obsoleted by the other commands for ioctl(2) such as
SNDRV_PCM_IOCTL_CHANNEL_INFO.
This commit removes the long-abandoned command, bye.
Takashi Iwai [Tue, 13 Jun 2017 13:57:28 +0000 (15:57 +0200)]
ALSA: pcm: Skip ack callback without actual appl_ptr update
We call ack callback whenever appl_ptr gets updated via
pcm_lib_apply_appl_ptr(). There are various code paths to call this
function. A part of them are for read/write/forward/rewind, where the
appl_ptr is always changed and thus the call of ack is mandatory.
OTOH, another part of code paths are from the explicit user call,
e.g. via SYNC_PTR ioctl. There, we may receive the same appl_ptr
value, and in such a case, calling ack is obviously superfluous.
This patch adds the check of the given appl_ptr value, and returns
immediately if it's no real update.
Takashi Iwai [Tue, 24 May 2016 13:40:03 +0000 (15:40 +0200)]
ALSA: pcm: Preprocess PAUSED or SUSPENDED stream before PREPARE
Calling PREPARE ioctl to the stream in either PAUSED or SUSPENDED
state may confuse some drivers that don't handle the state properly.
Instead of fixing each driver, PCM core should take care of the proper
state change before actually trying to (re-)prepare the stream.
Namely, when the stream is in PAUSED state, it triggers PAUSE_RELEASE,
and when in SUSPENDED state, it triggers STOP, before calling prepare
callbacks.
Takashi Iwai [Tue, 24 May 2016 13:08:31 +0000 (15:08 +0200)]
ALSA: pcm: Allow dropping stream directly after resume
So far, the PCM core refuses DROP ioctl when the stream in the
suspended state. This was basically to avoid the invalid state change
*during* the suspend. But since we protect the power change globally
in the common PCM ioctl caller side, it's guaranteed that
snd_pcm_drop() is called at the right power state. So we can assume
that the drop of stream is safe immediately after SUSPENDED state.
Takashi Iwai [Tue, 24 May 2016 13:07:39 +0000 (15:07 +0200)]
ALSA: pcm: Apply power lock globally to common ioctls
All PCM common ioctls should run only in the powered up state, but
currently only a few ioctls do the proper snd_power_lock() and
snd_power_wait() invocations. Instead of adding to each place, do it
commonly in the caller side, so that all these ioctls are assured to
be operated at the power up state.
Takashi Sakamoto [Mon, 12 Jun 2017 00:41:46 +0000 (09:41 +0900)]
ALSA: pcm: use %s instead of %c for format of PCM buffer tracepoints
As long as I know, in userspace, '%c' format on printing format for
tracepoint is replaced with '>c<' by existent tracing program; i.g.
'perf-trace' and 'trace-cmd'. This is inconvenient.
This commit replaces the format with '%s'. The length of letters in the
format string is not changed, thus this commit doesn't increase object
size.
In theory, I should work for improvements of these tracing programs, but
here I'd like to save my time to work for the other projects.
Takashi Sakamoto [Mon, 12 Jun 2017 00:41:45 +0000 (09:41 +0900)]
ALSA: pcm: add 'applptr' event of tracepoint
In design of ALSA PCM core, status and control data for runtime of ALSA
PCM substream are shared between kernel/user spaces by page frame
mapping with read-only attribute. Both of hardware-side and
application-side position on PCM buffer are maintained as a part of
the status data. In a view of ALSA PCM application, these two positions
can be updated by executing ioctl(2) with some commands.
There's an event of tracepoint for hardware-side position; 'hwptr'.
On the other hand, no events for application-side position. This commit
adds a new event for this purpose; 'applptr'. When the application-side
position is changed in kernel space, this event is probed with useful
information for developers.
I note that the event is not probed for all of ALSA PCM applications, When
applications are written by read/write programming scenario, the event is
surely probed. The applications execute ioctl(2) with
SNDRV_PCM_IOCTL_[READ|WRITE][N/I]_FRAMES to read/write any PCM frame, then
ALSA PCM core updates the application-side position in kernel land.
However, when applications are written by mmap programming scenario, if
maintaining the application side position in kernel space accurately,
applications should voluntarily execute ioctl(2) with
SNDRV_PCM_IOCTL_SYNC_PTR to commit the number of handled PCM frames. If
not voluntarily, the application-side position is not changed, thus the
added event is not probed.
There's a loophole, using architectures to which ALSA PCM core judges
non cache coherent. In this case, the status and control data is not mapped
into processe's VMA for any applications. Userland library, alsa-lib, is
programmed for this case. It executes ioctl(2) with
SNDRV_PCM_IOCTL_SYNC_PTR command every time to requiring the status and
control data.
ARM is such an architecture. Below is an example with serial sound interface
(ssi) on i.mx6 quad core SoC. I use v4.1 kernel released by fsl-community
with patches from VIA Tech. Inc. for VAB820, and my backport patches for
relevant features for this patchset. I use Ubuntu 17.04 from
ports.ubuntu.com as user land for armhf architecture.
We can surely see 'applptr' event is probed even if the application run
for mmap programming scenario ('-M' option and 'hw' plugin). Below is a
result of strace:
We can see 7 calls of ioctl(2) with SNDRV_PCM_IOCTL_SYNC_PTR per loop with
call of poll(2). 128 PCM frames are transferred per loop of one poll(2),
because the PCM substream is configured with S16_LE format and 1 channel
(2 byte * 1 * 128 = 256 bytes). This equals to the size of period of PCM
buffer. Comparing to the probed data, one of the 7 calls of ioctl(2) is
actually used to commit the number of copied PCM frames to kernel space.
The other calls are just used to check runtime status of PCM substream;
e.g. XRUN.
The tracepoint event is useful to investigate this case. I note that below
modules are related to the above sample.
My additional note is lock acquisition. The event is probed under acquiring
PCM stream lock. This means that calculation in the event is free from
any hardware events.
Takashi Sakamoto [Mon, 12 Jun 2017 00:41:44 +0000 (09:41 +0900)]
ALSA: pcm: unify codes to operate application-side position on PCM buffer
In a series of recent work, ALSA PCM core got some arrangements to handle
application-side position on PCM buffer. However, relevant codes still
disperse to two translation units
This commit unifies these codes into a helper function.
Takashi Iwai [Fri, 9 Jun 2017 13:11:58 +0000 (15:11 +0200)]
ALSA: seq: Allow the modular sequencer registration
Many drivers bind the sequencer stuff in off-load by another driver
module, so that it's loaded only on demand. In the current code, this
mechanism doesn't work when the driver is built-in while the sequencer
is module. We check with IS_REACHABLE() and enable only when the
sequencer is in the same level of build.
However, this is basically a overshoot. The binder code
(snd-seq-device) is an individual module from the sequencer core
(snd-seq), and we just have to make the former a built-in while
keeping the latter a module for allowing the scenario like the above.
This patch achieves that by rewriting Kconfig slightly. Now, a driver
that provides the manual sequencer device binding should select
CONFIG_SND_SEQ_DEVICE in a way as
select SND_SEQ_DEVICE if SND_SEQUENCER != n
Note that the "!=n" is needed here to avoid the influence of the
sequencer core is module while the driver is built-in.
Also, since rawmidi.o may be linked with snd_seq_device.o when
built-in, we have to shuffle the code to make the linker happy.
(the kernel linker isn't smart enough yet to handle such a case.)
That is, snd_seq_device.c is moved to sound/core from sound/core/seq,
as well as Makefile.
Last but not least, the patch replaces the code using IS_REACHABLE()
with IS_ENABLED(), since now the condition meets always when enabled.
Takashi Sakamoto [Sun, 11 Jun 2017 14:56:12 +0000 (23:56 +0900)]
ALSA: pcm: return error immediately for parameters handling
When refining mask/interval parameters, helper functions can return error
code. This error is not handled immediately. This seems to return
parameters to userspace applications in its meddle of processing.
However, in general, when receiving error from system calls, the
application might not handle argument buffer. It's reasonable to
judge the above design as superfluity.
Takashi Iwai [Fri, 9 Jun 2017 12:57:51 +0000 (14:57 +0200)]
ALSA: synth: Select snd-emux-synth explicitly
Instead of the non-standard way to enable the build of snd-emux-synth
module inside Makefile, rewrite Kconfig to select the item explicitly
from each driver (sbawe and emu10k1). This is the standard way.
Takashi Iwai [Fri, 9 Jun 2017 12:40:18 +0000 (14:40 +0200)]
ALSA: seq: Reorganize kconfig and build
This is a slightly intensive rewrite of Kconfig and Makefile about
ALSA sequencer stuff.
The first major change is that the kconfig items for the sequencer are
moved to sound/core/seq/Kconfig. OK, that's easy.
The substantial change is that, instead of hackish top-level module
selection in Makefile, we define a Kconfig item for each sequencer
module. The driver that requires such sequencer components select
exclusively the kconfig items. This is more straightforward and
standard way.
Takashi Iwai [Fri, 9 Jun 2017 12:06:46 +0000 (14:06 +0200)]
ALSA: seq: Allow the tristate build of OSS emulation
Currently OSS sequencer emulation is tied with ALSA sequencer core,
both are built in the same level; i.e. when CONFIG_SND_SEQUENCER=y,
the OSS sequencer emulation is also always built-in, even though the
functionality can be built as an individual module.
This patch changes the rule and allows users to build snd-seq-oss
module while others are built-in. Essentially, it's just a few simple
changes in Kconfig and Makefile. Some driver codes like opl3 need to
convert from the simple ifdef to IS_ENABLED(). But that's all.
You might wonder how about the dependency: right, it can be messy, but
it still works. Since we rewrote the sequencer binding with the
standard bus, the driver can be bound at any time on demand. So, the
synthesizer driver module can be loaded individually from the OSS
emulation core before/after it.
Takashi Iwai [Fri, 9 Jun 2017 11:56:05 +0000 (13:56 +0200)]
ALSA: Make CONFIG_SND_OSSEMUL user-selectable
Currently CONFIG_SND_OSSEMUL is selected by each config like
CONFIG_SND_PCM_OSS. But, as see in the raw MIDI code that is built
conditionally with CONFIG_SND_OSSEMUL, we should rather make
CONFIG_SND_OSSEMUL user-selectable as the top kconfig item, and leave
the rest depending on it.
ALSA: pcm: add tracepoints for final selection process of hardware parameters
Results of ioctl(2) with SNDRV_PCM_IOCTL_HW_REFINE and
SNDRV_PCM_IOCTL_HW_PARAMS are different, because the latter has single
value for several parameters; e.g. channels of PCM substream. Selection
of the single value is done independently of application of constraints.
It's helpful for developers to trace the selection process.
This commit adds tracepoints to snd_pcm_hw_params_choose() for the
purpose.
As of v4.12, snd_pcm_hw_params_choose() is just called in a process
context of ioctl(2) with SNDRV_PCM_IOCTL_HW_PARAMS. The function locates
in a different file, which has no tracepoints.
This commit moves the function to a file with the tracepoints for later
commit.
ALSA: pcm: move fixup of info flag after selecting single parameters
When drivers register no flags about information of PCM hardware, ALSA
PCM core fixups it roughly. Currently, this operation places in a
function snd_pcm_hw_refine(). It can be moved to a function
fixup_unreferenced_params() because it doesn't affects operations
between these two functions.
This idea is better to bundle codes with similar purposes and this commit
achieves it.
ALSA: pcm: calculate non-mask/non-interval parameters always when possible
A structure for parameters of PCM runtime has parameters which are
not classified as mask/interval type. They are decided only when
corresponding normal parameters have unique values.
* struct snd_pcm_hw_params.msbits
* struct snd_pcm_hw_params.rate_num
* struct snd_pcm_hw_params.rate_den
* struct snd_pcm_hw_params.fifo_size
Current implementation of hw_params ioctl sometimes doesn't decide these
parameters even if corresponding parameters are fixed, because these
parameters are evaluated before a call of snd_pcm_hw_params_choose().
This commit adds a helper function to process the parameters and call it
in proper positions.
ALSA: pcm: add comment about application of rule to PCM parameters
Drivers add rules of parameters to runtime of PCM substream, when
applications open ALSA PCM character device. When applications call
ioctl(2) with SNDRV_PCM_IOCTL_HW_REFINE or SNDRV_PCM_IOCTL_HW_PARAMS, the
rules are applied to the parameters and return the result to user space.
The rule can have dependency between parameters. Additionally, it can have
condition flags about application of rules. Userspace applications can
indicate the flags to suppress change of parameters.
ALSA: pcm: use helper functions to check whether parameters are determined
A commit 8bea869c5e56 ("ALSA: PCM midlevel: improve fifo_size handling")
allows drivers to implement calculation of fifo size in parameter
structure. This calculation runs only when two of the other parameters
have single value.
In ALSA PCM core, there're some helper functions for the case. This commit
applies the functions instead of value comparison.
This commit modifies current for readability in below aspects:
- use bool type variable instead of int type variable assigned to 0/1
- move variable definition from loop to top of the function definition
ALSA: pcm: remove function local variable with alternative evaluation
A local variable is used to judge whether a parameter should be handled
due to reverse dependency of the other rules. However, this can be
obsoleted by check of a sentinel in dependency array.
This commit removes the local variable and check the sentinel to reduce
stack usage.
ALSA: pcm: use goto statement instead of while statement to reduce indentation
In a process to calculate parameters of PCM substream, application of all
rules is iterated several times till parameter dependencies are satisfied.
In current implementation, two loops are used for the design, however this
brings two-level indentation and decline readability.
This commit attempts to reduce the indentation by using goto statement,
instead of outer while loop.
ALSA: pcm: add a helper function to apply parameter rules
Application of rules to parameters of PCM substream is done in a call of
snd_pcm_hw_refine(), while the function includes much codes and is not
enough friendly to readers.
This commit splits the codes to a separated function so that readers can
get it easily. I leave desicion into compilers to merge the function into
its callee.
ALSA: pcm: add a helper function to constrain interval-type parameters
Application of constraints to interval-type parameters for PCM substream
is done in a call of snd_pcm_hw_refine(), while the function includes
much codes and is not enough friendly to readers.
This commit splits the codes to a separated function so that readers can
get it easily. I leave desicion into compilers to merge the function into
its callee.
ALSA: pcm: add a helper function to constrain mask-type parameters
Application of constraints to mask-type parameters for PCM substream is
done in a call of snd_pcm_hw_refine(), while the function includes much
codes and is not enough friendly to readers.
This commit splits the codes to a separated function so that readers can
get it easily. I leave desicion into compilers to merge the function into
its callee.
ALSA: pcm: enable parameter tracepoints only when CONFIG_SND_DEBUG is enabled
In a previous commit, tracepoints are added for PCM parameter processing.
As long as I know, this implementation increases size of relocatable
object by 35%. For vendors who are conscious of memory footprint, it
brings apparent disadvantage.
This commit utilizes CONFIG_SND_DEBUG configuration to enable/disable the
tracepoints.
ALSA: pcm: tracepoints for refining PCM parameters
When working for devices which support configurable modes for its data
transmission or which consists of several components, developers are
likely to use rules of parameters of PCM substream. However, there's no
infrastructure to assist their work.
In old days, ALSA PCM core got a local 'RULES_DEBUG' macro to debug
refinement of parameters for PCM substream. Although this is merely a
makeshift. With some modifications, we get the infrastructure.
This commit is for the purpose. Refinement of mask/interval type of
PCM parameters is probed as tracepoint events as 'hw_mask_param' and
'hw_interval_param' on existent 'snd_pcm' subsystem.
Takashi Iwai [Fri, 2 Jun 2017 15:16:59 +0000 (17:16 +0200)]
ALSA: timer: Improve user queue reallocation
ALSA timer may reallocate the user queue upon request, and it happens
at three places for now: at opening, at SNDRV_TIMER_IOCTL_PARAMS, and
at SNDRV_TIMER_IOCTL_SELECT. However, the last one,
snd_timer_user_tselect(), doesn't need to reallocate the buffer since
it doesn't change the queue size. It does just because tu->tread
might have been changed before starting the timer.
Instead of *_SELECT ioctl, we should reallocate the queue at
SNDRV_TIMER_IOCTL_TREAD; then the timer is guaranteed to be stopped,
thus we can reassign the buffer more safely.
This patch implements that with a slight code refactoring.
Essentially, the patch achieves:
- Introduce realloc_user_queue() for (re-)allocating the ring buffer,
and call it from all places. Also, realloc_user_queue() uses
kcalloc() for avoiding possible leaks.
- Add the buffer reallocation at SNDRV_TIMER_IOCTL_TREAD. When it
fails, tu->tread is restored to the old value, too.
- Drop the buffer reallocation at snd_timer_user_tselect().
Tested-by: Alexander Potapenko <glider@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Iwai [Fri, 2 Jun 2017 15:26:56 +0000 (17:26 +0200)]
ALSA: timer: Fix missing queue indices reset at SNDRV_TIMER_IOCTL_SELECT
snd_timer_user_tselect() reallocates the queue buffer dynamically, but
it forgot to reset its indices. Since the read may happen
concurrently with ioctl and snd_timer_user_tselect() allocates the
buffer via kmalloc(), this may lead to the leak of uninitialized
kernel-space data, as spotted via KMSAN:
BUG: KMSAN: use of unitialized memory in snd_timer_user_read+0x6c4/0xa10
CPU: 0 PID: 1037 Comm: probe Not tainted 4.11.0-rc5+ #2739
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:16
dump_stack+0x143/0x1b0 lib/dump_stack.c:52
kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:1007
kmsan_check_memory+0xc2/0x140 mm/kmsan/kmsan.c:1086
copy_to_user ./arch/x86/include/asm/uaccess.h:725
snd_timer_user_read+0x6c4/0xa10 sound/core/timer.c:2004
do_loop_readv_writev fs/read_write.c:716
__do_readv_writev+0x94c/0x1380 fs/read_write.c:864
do_readv_writev fs/read_write.c:894
vfs_readv fs/read_write.c:908
do_readv+0x52a/0x5d0 fs/read_write.c:934
SYSC_readv+0xb6/0xd0 fs/read_write.c:1021
SyS_readv+0x87/0xb0 fs/read_write.c:1018
This patch adds the missing reset of queue indices. Together with the
previous fix for the ioctl/read race, we cover the whole problem.
Reported-by: Alexander Potapenko <glider@google.com> Tested-by: Alexander Potapenko <glider@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Takashi Iwai [Fri, 2 Jun 2017 13:03:38 +0000 (15:03 +0200)]
ALSA: timer: Fix race between read and ioctl
The read from ALSA timer device, the function snd_timer_user_tread(),
may access to an uninitialized struct snd_timer_user fields when the
read is concurrently performed while the ioctl like
snd_timer_user_tselect() is invoked. We have already fixed the races
among ioctls via a mutex, but we seem to have forgotten the race
between read vs ioctl.
This patch simply applies (more exactly extends the already applied
range of) tu->ioctl_lock in snd_timer_user_tread() for closing the
race window.
Reported-by: Alexander Potapenko <glider@google.com> Tested-by: Alexander Potapenko <glider@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
ALSA fireface driver has ALSA specific operations for MIDI/PCM data.
Structured data for the operations can be constified. Additionally,
The structured data can be function local.
ALSA: firewire: process packets in 'struct snd_pcm_ops.ack' callback
In recent commit for ALSA PCM core, some arrangement is done for
'struct snd_pcm_ops.ack' callback. This is called when appl_ptr is
explicitly moved in intermediate buffer for PCM frames, except for
some cases described later.
For drivers in ALSA firewire stack, usage of this callback has a merit to
reduce latency between time of PCM frame queueing and handling actual
packets in recent isochronous cycle, because no need to wait for software
IRQ context from isochronous context of OHCI 1394.
If this works well in a case that mapped page frame is used for the
intermediate buffer, user process should execute some commands for ioctl(2)
to tell the number of handled PCM frames in the intermediate buffer just
after handling them. Therefore, at present, with a combination of below
conditions, this doesn't work as expected and user process should wait for
the software IRQ context as usual:
- when ALSA PCM core judges page frame mapping is available for status
data (struct snd_pcm_mmap_status) and control data
(struct snd_pcm_mmap_control).
- user process handles PCM frames by loop just with 'snd_pcm_mmap_begin()'
and 'snd_pcm_mmap_commit()'.
- user process uses PCM hw plugin in alsa-lib to operate I/O without
'sync_ptr_ioctl' option.
Unfortunately, major use case include these three conditions.
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