IF YOU WOULD LIKE TO GET AN ACCOUNT, please write an
email to Administrator. User accounts are meant only to access repo
and report issues and/or generate pull requests.
This is a purpose-specific Git hosting for
BaseALT
projects. Thank you for your understanding!
Только зарегистрированные пользователи имеют доступ к сервису!
Для получения аккаунта, обратитесь к администратору.
-----BEGIN PGP SIGNATURE-----
iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAmBzdS0eHHRvcnZhbGRz
QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGDdAIAIpKH/tAHhH7s7QH
m5ewgE8foP7M5Ue9fp3+JmbtaYSzhCAMcKhqGtat/zk5PvA9AoYCDXrTetfYtBHh
LUOmhL9hcKItNobfkYBok6BiFjGUEL3HMqz5w+MUsMwnXIc4RXqfJmsQ932z9Kxf
yDwe6ehIzJVrQLI/C0mTamYRHu2aiZ1VWzhKuT493rLeg0R2odCCIClPN+/QvCwb
8/sk6l1c8eOUYYMUzKFZifaZGb12qDjRt4pZmk51aMTzg0WCpElJG+7Uqr4QQhZP
p6xeNuUQq6WwxtlDkmo79Uzkrurb5tN2/hZ1RcJhs3EdHfpR0MjIyH3Znnb31gnu
39VjHhg=
=4KP/
-----END PGP SIGNATURE-----
Merge tag 'v5.12-rc7' into driver-core-next
We need the driver core fix in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We now have three places within the same file doing the same operation
of freeing this pointer and setting it anew. A helper makes this
arguably easier to read, so add one.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20210323153714.25120-2-a.fatoum@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
deferred_probe_timeout kernel commandline parameter allows probing of
consumer devices if the supplier devices don't have any drivers.
fw_devlink=on will indefintely block probe() calls on a device if all
its suppliers haven't probed successfully. This completely skips calls
to driver_deferred_probe_check_state() since that's only called when a
.probe() function calls framework APIs. So fw_devlink=on breaks
deferred_probe_timeout.
deferred_probe_timeout in its current state also ignores a lot of
information that's now available to the kernel. It assumes all suppliers
that haven't probed when the timer expires (or when initcalls are done
on a static kernel) will never probe and fails any calls to acquire
resources from these unprobed suppliers.
However, this assumption by deferred_probe_timeout isn't true under many
conditions. For example:
- If the consumer happens to be before the supplier in the deferred
probe list.
- If the supplier itself is waiting on its supplier to probe.
This patch fixes both these issues by relaxing device links between
devices only if the supplier doesn't have any driver that could match
with (NOT bound to) the supplier device. This way, we only fail attempts
to acquire resources from suppliers that truly don't have any driver vs
suppliers that just happen to not have probed yet.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210402040342.2944858-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
list_for_each_entry_safe() is only useful if we are deleting nodes in a
linked list within the loop. It doesn't protect against other threads
adding/deleting nodes to the list in parallel. We need to grab
deferred_probe_mutex when traversing the deferred_probe_pending_list.
Cc: stable@vger.kernel.org
Fixes: 25b4e70dcc ("driver core: allow stopping deferred probe after init")
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210402040342.2944858-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When device_create_file() fails and returns a non-zero value,
no error return code of driver_sysfs_add() is assigned.
To fix this bug, ret is assigned with the return value of
device_create_file(), and then ret is checked.
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Link: https://lore.kernel.org/r/20210324023405.12465-1-baijiaju1990@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Deferred probe usually runs only on pinned kworkers, which might take
longer time if a device contains multiple sub-devices. One such case
is of sound card on mobile devices, where we have good number of
mixers and controls per mixer.
We observed boot up improvement - deferred probes take ~600ms when bound
to little core kworker and ~200ms when deferred probe is queued on
unbound wq. This is due to scheduler moving the worker running deferred
probe work to big CPUs. Without this change, we see the worker is running
on LITTLE CPU due to affinity.
Since kworker runs deferred probe of several devices, the locality may
not be important. Also, init thread executing driver initcalls, can
potentially migrate as it has cpu affinity set to all cpus.In addition
to this, async probes use unbounded workqueue. So, using unbounded wq for
deferred probes looks to be similar to these w.r.t. scheduling behavior.
Signed-off-by: Yogesh Lal <ylal@codeaurora.org>
Link: https://lore.kernel.org/r/1616583698-6398-1-git-send-email-ylal@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When retrying a deferred probe, any old defer reason string should be
discarded. Otherwise, if the probe is deferred again at a different spot,
but without setting a message, the now incorrect probe reason will remain.
This was observed with the i.MX I2C driver, which ultimately failed
to probe due to lack of the GPIO driver. The probe defer for GPIO
doesn't record a message, but a previous probe defer to clock_get did.
This had the effect that /sys/kernel/debug/devices_deferred listed
a misleading probe deferral reason.
Cc: stable <stable@vger.kernel.org>
Fixes: d090b70ede ("driver core: add deferring probe reason to devices_deferred property")
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20210319110459.19966-1-a.fatoum@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There's no point in adding a device to the deferred probe list if we
know for sure that it doesn't have a matching driver. So, check if a
device can match with a driver before adding it to the deferred probe
list.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210302211133.2244281-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
No need to save the debugfs dentry for the "devices_deferred" debugfs
file (gotta love the juxtaposition), if we need to remove it we can look
it up from debugfs itself.
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20210216142400.3759099-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 5b6164d346.
Stephan reports problems with this commit, so revert it for now.
Fixes: 5b6164d346 ("driver core: Reorder devices on successful probe")
Link: https://lore.kernel.org/r/X/ycQpu7NIGI969v@gerhold.net
Reported-by: Stephan Gerhold <stephan@gerhold.net>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Rafael. J. Wysocki <rafael@kernel.org>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There will be memory leak if driver probe failed. Trace as below:
backtrace:
[<000000002415258f>] kmemleak_alloc+0x3c/0x50
[<00000000f447ebe4>] __kmalloc+0x208/0x530
[<0000000048bc7b3a>] of_dma_get_range+0xe4/0x1b0
[<0000000041e39065>] of_dma_configure_id+0x58/0x27c
[<000000006356866a>] platform_dma_configure+0x2c/0x40
......
[<000000000afcf9b5>] ret_from_fork+0x10/0x3c
This issue is introduced by commit e0d072782c73("dma-mapping:
introduce DMA range map, supplanting dma_pfn_offset "). It doesn't
free dma_range_map when driver probe failed and cause above
memory leak. So, add code to free it in error path.
Fixes: e0d072782c ("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset ")
Cc: stable@vger.kernel.org
Signed-off-by: Meng Li <Meng.Li@windriver.com>
Link: https://lore.kernel.org/r/20210105070927.14968-1-Meng.Li@windriver.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Device drivers usually depend on the fact that the devices that they
control are suspended in the same order that they were probed in. In
most cases this is already guaranteed via deferred probe.
However, there's one case where this can still break: if a device is
instantiated before a dependency (for example if it appears before the
dependency in device tree) but gets probed only after the dependency is
probed. Instantiation order would cause the dependency to get probed
later, in which case probe of the original device would be deferred and
the suspend/resume queue would get reordered properly. However, if the
dependency is provided by a built-in driver and the device depending on
that driver is controlled by a loadable module, which may only get
loaded after the root filesystem has become available, we can be faced
with a situation where the probe order ends up being different from the
suspend/resume order.
One example where this happens is on Tegra186, where the ACONNECT is
listed very early in device tree (sorted by unit-address) and depends on
BPMP (listed very late because it has no unit-address) for power domains
and clocks/resets. If the ACONNECT driver is built-in, there is no
problem because it will be probed before BPMP, causing a probe deferral
and that in turn reorders the suspend/resume queue. However, if built as
a module, it will end up being probed after BPMP, and therefore not
result in a probe deferral, and therefore the suspend/resume queue will
stay in the instantiation order. This in turn causes problems because
ACONNECT will be resumed before BPMP, which will result in a hang
because the ACONNECT's power domain cannot be powered on as long as the
BPMP is still suspended.
Fix this by always reordering devices on successful probe. This ensures
that the suspend/resume queue is always in probe order and hence meets
the natural expectations of drivers vs. their dependencies.
Reported-by: Jonathan Hunter <jonathanh@nvidia.com>
Acked-by: Rafael. J. Wysocki <rafael@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20201203175756.1405564-1-thierry.reding@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 716a7a2596.
The fw_devlink_pause/resume() APIs added by the commit being reverted
were a first cut attempt at optimizing boot time. But these APIs don't
fully solve the problem and are very fragile (can only be used for the
top level devices being added). This series replaces them with a much
better optimization that works for all device additions and also has the
benefit of reducing the complexity of the firmware (DT, EFI) specific
code and abstracting out common code to driver core.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201121020232.908850-7-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit fefcfc9687.
The reverted commit is fixing commit 716a7a2596 ("driver core:
fw_devlink: Add support for batching fwnode parsing"). Since the
original commit will be reverted, the fix can be reverted too.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201121020232.908850-5-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit cec72f3efc.
Commit cec72f3efc ("driver core: Don't do deferred probe in parallel
with kernel_init thread") was fixing a commit 716a7a2596 ("driver
core: fw_devlink: Add support for batching fwnode parsing"). Since the
commit being fixed itself is going to be reverted, the fix can also be
reverted.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201121020232.908850-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since the device is resumed from runtime-suspend in
__device_release_driver() anyway, it is better to do that before
looking for busy managed device links from it to consumers, because
if there are any, device_links_unbind_consumers() will be called
and it will cause the consumer devices' drivers to unbind, so the
consumer devices will be runtime-resumed. In turn, resuming each
consumer device will cause the supplier to be resumed and when the
runtime PM references from the given consumer to it are dropped, it
may be suspended. Then, the runtime-resume of the next consumer
will cause the supplier to resume again and so on.
Update the code accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Fixes: 9ed9895370 ("driver core: Functional dependencies tracking support")
Cc: All applicable <stable@vger.kernel.org> # All applicable
Tested-by: Xiang Chen <chenxiang66@hisilicon.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After commit d12544fb2a ("PM: runtime: Remove link state checks in
rpm_get/put_supplier()") nothing prevents the consumer device's
runtime PM from acquiring additional references to the supplier
device after pm_runtime_clean_up_links() has run (or even while it
is running), so calling this function from __device_release_driver()
may be pointless (or even harmful).
Moreover, it ignores stateless device links, so the runtime PM
handling of managed and stateless device links is inconsistent
because of it, so better get rid of it entirely.
Fixes: d12544fb2a ("PM: runtime: Remove link state checks in rpm_get/put_supplier()")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: 5.1+ <stable@vger.kernel.org> # 5.1+
Tested-by: Xiang Chen <chenxiang66@hisilicon.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
- rework the non-coherent DMA allocator
- move private definitions out of <linux/dma-mapping.h>
- lower CMA_ALIGNMENT (Paul Cercueil)
- remove the omap1 dma address translation in favor of the common
code
- make dma-direct aware of multiple dma offset ranges (Jim Quinlan)
- support per-node DMA CMA areas (Barry Song)
- increase the default seg boundary limit (Nicolin Chen)
- misc fixes (Robin Murphy, Thomas Tai, Xu Wang)
- various cleanups
-----BEGIN PGP SIGNATURE-----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=Bkf/
-----END PGP SIGNATURE-----
Merge tag 'dma-mapping-5.10' of git://git.infradead.org/users/hch/dma-mapping
Pull dma-mapping updates from Christoph Hellwig:
- rework the non-coherent DMA allocator
- move private definitions out of <linux/dma-mapping.h>
- lower CMA_ALIGNMENT (Paul Cercueil)
- remove the omap1 dma address translation in favor of the common code
- make dma-direct aware of multiple dma offset ranges (Jim Quinlan)
- support per-node DMA CMA areas (Barry Song)
- increase the default seg boundary limit (Nicolin Chen)
- misc fixes (Robin Murphy, Thomas Tai, Xu Wang)
- various cleanups
* tag 'dma-mapping-5.10' of git://git.infradead.org/users/hch/dma-mapping: (63 commits)
ARM/ixp4xx: add a missing include of dma-map-ops.h
dma-direct: simplify the DMA_ATTR_NO_KERNEL_MAPPING handling
dma-direct: factor out a dma_direct_alloc_from_pool helper
dma-direct check for highmem pages in dma_direct_alloc_pages
dma-mapping: merge <linux/dma-noncoherent.h> into <linux/dma-map-ops.h>
dma-mapping: move large parts of <linux/dma-direct.h> to kernel/dma
dma-mapping: move dma-debug.h to kernel/dma/
dma-mapping: remove <asm/dma-contiguous.h>
dma-mapping: merge <linux/dma-contiguous.h> into <linux/dma-map-ops.h>
dma-contiguous: remove dma_contiguous_set_default
dma-contiguous: remove dev_set_cma_area
dma-contiguous: remove dma_declare_contiguous
dma-mapping: split <linux/dma-mapping.h>
cma: decrease CMA_ALIGNMENT lower limit to 2
firewire-ohci: use dma_alloc_pages
dma-iommu: implement ->alloc_noncoherent
dma-mapping: add new {alloc,free}_noncoherent dma_map_ops methods
dma-mapping: add a new dma_alloc_pages API
dma-mapping: remove dma_cache_sync
53c700: convert to dma_alloc_noncoherent
...
Split out all the bits that are purely for dma_map_ops implementations
and related code into a new <linux/dma-map-ops.h> header so that they
don't get pulled into all the drivers. That also means the architecture
specific <asm/dma-mapping.h> is not pulled in by <linux/dma-mapping.h>
any more, which leads to a missing includes that were pulled in by the
x86 or arm versions in a few not overly portable drivers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Change additional instances that could use sysfs_emit and sysfs_emit_at
that the coccinelle script could not convert.
o macros creating show functions with ## concatenation
o unbound sprintf uses with buf+len for start of output to sysfs_emit_at
o returns with ?: tests and sprintf to sysfs_emit
o sysfs output with struct class * not struct device * arguments
Miscellanea:
o remove unnecessary initializations around these changes
o consistently use int len for return length of show functions
o use octal permissions and not S_<FOO>
o rename a few show function names so DEVICE_ATTR_<FOO> can be used
o use DEVICE_ATTR_ADMIN_RO where appropriate
o consistently use const char *output for strings
o checkpatch/style neatening
Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/8bc24444fe2049a9b2de6127389b57edfdfe324d.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use the ktime_us_delta() helper to measure the driver probe time. Given the
helpers already returns an s64 value, let's drop the unnecessary casting to
s64 as well. There is no functional change.
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20200803033343.1178-1-yuzenghui@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
/sys/kernel/debug/devices_deferred property contains list of deferred devices.
This list does not contain reason why the driver deferred probe, the patch
improves it.
The natural place to set the reason is dev_err_probe function introduced
recently, ie. if dev_err_probe will be called with -EPROBE_DEFER instead of
printk the message will be attached to a deferred device and printed when user
reads devices_deferred property.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20200713144324.23654-3-a.hajda@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 3451a495ef ("driver core: Establish order of operations for
device_add and device_del via bitflag") sought to prevent asynchronous
driver binding to a device which is being removed. It added a
per-device "dead" flag which is checked in the following code paths:
* asynchronous binding in __driver_attach_async_helper()
* synchronous binding in device_driver_attach()
* asynchronous binding in __device_attach_async_helper()
It did *not* check the flag upon:
* synchronous binding in __device_attach()
However __device_attach() may also be called asynchronously from:
deferred_probe_work_func()
bus_probe_device()
device_initial_probe()
__device_attach()
So if the commit's intention was to check the "dead" flag in all
asynchronous code paths, then a check is also necessary in
__device_attach(). Add the missing check.
Fixes: 3451a495ef ("driver core: Establish order of operations for device_add and device_del via bitflag")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v5.1+
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Link: https://lore.kernel.org/r/de88a23a6fe0ef70f7cfd13c8aea9ab51b4edab6.1594214103.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
syzbot is reporting hung task in wait_for_device_probe() [1]. At least,
we always need to decrement probe_count if we incremented probe_count in
really_probe().
However, since I can't find "Resources present before probing" message in
the console log, both "this message simply flowed off" and "syzbot is not
hitting this path" will be possible. Therefore, while we are at it, let's
also prepare for concurrent wait_for_device_probe() calls by replacing
wake_up() with wake_up_all().
[1] https://syzkaller.appspot.com/bug?id=25c833f1983c9c1d512f4ff860dd0d7f5a2e2c0f
Reported-by: syzbot <syzbot+805f5f6ae37411f15b64@syzkaller.appspotmail.com>
Fixes: 7c35e699c8 ("driver core: Print device when resources present in really_probe()")
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20200713021254.3444-1-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This can be used to check if a device supports sync_state() callbacks
and therefore keeps resources left on by the bootloader enabled till all
its consumers have probed.
This can also be used to check if sync_state() has been called for a
device or whether it is still trying to keep resources enabled because
they were left enabled by the bootloader and all its consumers haven't
probed yet.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200521191800.136035-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The current deferred probe implementation can mess up suspend/resume
ordering if deferred probe thread is kicked off in parallel with the
main initcall thread (kernel_init thread) [1].
For example:
Say device-B is a consumer of device-A.
Initcall thread Deferred probe thread
=============== =====================
1. device-A is added.
2. device-B is added.
3. dpm_list is now [device-A, device-B].
4. driver-A defers probe of device-A.
5. device-A is moved to
end of dpm_list
6. dpm_list is now
[device-B, device-A]
7. driver-B is registereed and probes device-B.
8. dpm_list stays as [device-B, device-A].
The reverse order of dpm_list is used for suspend. So in this case
device-A would incorrectly get suspended before device-B.
Commit 716a7a2596 ("driver core: fw_devlink: Add support for batching
fwnode parsing") kicked off the deferred probe thread early during boot
to run in parallel with the initcall thread and caused suspend/resume
regressions. This patch removes the parallel run of the deferred probe
thread to avoid the suspend/resume regressions.
[1] - https://lore.kernel.org/lkml/CAGETcx8W96KAw-d_siTX4qHB_-7ddk0miYRDQeHE6E0_8qx-6Q@mail.gmail.com/
Fixes: 716a7a2596 ("driver core: fw_devlink: Add support for batching fwnode parsing")
Signed-off-by: Saravana Kannan <saravanak@google.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200701194259.3337652-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The whole point behind adding driver_deferred_probe_force_trigger() in
commit 716a7a2596 ("driver core: fw_devlink: Add support for batching
fwnode parsing") was to skip the check for driver_deferred_probe_enable.
Otherwise, it's identical to driver_deferred_probe_trigger().
Delete the check in driver_deferred_probe_force_trigger() so that
fw_devlink_pause() and fw_devlink_resume() can kick off deferred probe
as intended. Without doing this forced deferred probe trigger, some
platforms seem to be crashing during boot because they assume probe
order of devices.
Fixes: 716a7a2596 ("driver core: fw_devlink: Add support for batching fwnode parsing")
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200517173453.157703-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The amount of time spent parsing fwnodes of devices can become really
high if the devices are added in an non-ideal order. Worst case can be
O(N^2) when N devices are added. But this can be optimized to O(N) by
adding all the devices and then parsing all their fwnodes in one batch.
This commit adds fw_devlink_pause() and fw_devlink_resume() to allow
doing this.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200515053500.215929-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We want the driver core fixes in here and this resolves a merge issue
with drivers/base/dd.c
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Message logged by 'dev_xxx()' or 'pr_xxx()' should end with a '\n'.
While at it, convert some "printk(KERN_" into equivalent but less verbose
(pr|dev)_xxx functions.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20200411133158.27390-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In commit c8c43cee29 ("driver core: Fix
driver_deferred_probe_check_state() logic"), we set the default
driver_deferred_probe_timeout value to 30 seconds to allow for
drivers that are missing dependencies to have some time so that
the dependency may be loaded from userland after initcalls_done
is set.
However, Yoshihiro Shimoda reported that on his device that
expects to have unmet dependencies (due to "optional links" in
its devicetree), was failing to mount the NFS root.
In digging further, it seemed the problem was that while the
device properly probes after waiting 30 seconds for any missing
modules to load, the ip_auto_config() had already failed,
resulting in NFS to fail. This was due to ip_auto_config()
calling wait_for_device_probe() which doesn't wait for the
driver_deferred_probe_timeout to fire.
This patch tries to fix the issue by creating a waitqueue
for the driver_deferred_probe_timeout, and calling wait_event()
to make sure driver_deferred_probe_timeout is zero in
wait_for_device_probe() to make sure all the probing is
finished.
The downside to this solution is that kernel functionality that
uses wait_for_device_probe(), will block until the
driver_deferred_probe_timeout fires, regardless of if there is
any missing dependencies.
However, the previous patch reverts the default timeout value to
zero, so this side-effect will only affect users who specify a
driver_deferred_probe_timeout= value as a boot argument, where
the additional delay would be beneficial to allow modules to
load later during boot.
Thanks to Geert for chasing down that ip_auto_config was why NFS
was failing in this case!
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rob Herring <robh@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Basil Eljuse <Basil.Eljuse@arm.com>
Cc: Ferry Toth <fntoth@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: linux-pm@vger.kernel.org
Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Fixes: c8c43cee29 ("driver core: Fix driver_deferred_probe_check_state() logic")
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200422203245.83244-4-john.stultz@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In commit c8c43cee29 ("driver core: Fix
driver_deferred_probe_check_state() logic") and following
changes the logic was changes slightly so that if there is no
driver to match whats found in the dtb, we wait the sepcified
seconds for modules to be loaded by userland, and then timeout,
where as previously we'd print "ignoring dependency for device,
assuming no driver" and immediately return -ENODEV after
initcall_done.
However, in the timeout case (which previously existed but was
practicaly un-used without a boot argument), the timeout message
uses dev_WARN(). This means folks are now seeing a big backtrace
in their boot logs if there a entry in their dts that doesn't
have a driver.
To fix this, lets use dev_warn(), instead of dev_WARN() to match
the previous error path.
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rob Herring <robh@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Basil Eljuse <Basil.Eljuse@arm.com>
Cc: Ferry Toth <fntoth@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: linux-pm@vger.kernel.org
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Fixes: c8c43cee29 ("driver core: Fix driver_deferred_probe_check_state() logic")
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200422203245.83244-3-john.stultz@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch addresses a regression in 5.7-rc1+
In commit c8c43cee29 ("driver core: Fix
driver_deferred_probe_check_state() logic"), we both cleaned up
the logic and also set the default driver_deferred_probe_timeout
value to 30 seconds to allow for drivers that are missing
dependencies to have some time so that the dependency may be
loaded from userland after initcalls_done is set.
However, Yoshihiro Shimoda reported that on his device that
expects to have unmet dependencies (due to "optional links" in
its devicetree), was failing to mount the NFS root.
In digging further, it seemed the problem was that while the
device properly probes after waiting 30 seconds for any missing
modules to load, the ip_auto_config() had already failed,
resulting in NFS to fail. This was due to ip_auto_config()
calling wait_for_device_probe() which doesn't wait for the
driver_deferred_probe_timeout to fire.
Fixing that issue is possible, but could also introduce 30
second delays in bootups for users who don't have any
missing dependencies, which is not ideal.
So I think the best solution to avoid any regressions is to
revert back to a default timeout value of zero, and allow
systems that need to utilize the timeout in order for userland
to load any modules that supply misisng dependencies in the dts
to specify the timeout length via the exiting documented boot
argument.
Thanks to Geert for chasing down that ip_auto_config was why NFS
was failing in this case!
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rob Herring <robh@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Basil Eljuse <Basil.Eljuse@arm.com>
Cc: Ferry Toth <fntoth@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Anders Roxell <anders.roxell@linaro.org>
Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: c8c43cee29 ("driver core: Fix driver_deferred_probe_check_state() logic")
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200422203245.83244-2-john.stultz@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There is a place in the code where open-coded version of list entry accessors
list_last_entry() is used.
Replace that with the standard macro.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200324122023.9649-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Between printing the debug message and actual check atomic counter can be
altered. For better debugging experience read atomic counter value only once.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Ferry Toth <fntoth@gmail.com>
Link: https://lore.kernel.org/r/20200324122023.9649-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since other subsystems (like regulator) have similar arbitrary
timeouts for how long they try to resolve driver dependencies,
rename deferred_probe_timeout to driver_deferred_probe_timeout
and set it as global, so it can be shared.
Cc: linux-pm@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200225050828.56458-6-john.stultz@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that driver_deferred_probe_check_state() works better, and
we've converted the only user of
driver_deferred_probe_check_state_continue() we can simply
remove it and simplify some of the logic.
Cc: linux-pm@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200225050828.56458-5-john.stultz@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When using modules, its common for the modules not to be loaded
until quite late by userland. With the current code,
driver_deferred_probe_check_state() will stop returning
EPROBE_DEFER after late_initcall, which can cause module
dependency resolution to fail after that.
So allow a longer window of 30 seconds (picked somewhat
arbitrarily, but influenced by the similar regulator core
timeout value) in the case where modules are enabled.
Cc: linux-pm@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200225050828.56458-3-john.stultz@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
driver_deferred_probe_check_state() has some uninituitive behavior.
* From boot to late_initcall, it returns -EPROBE_DEFER
* From late_initcall to the deferred_probe_timeout (if set)
it returns -ENODEV
* If the deferred_probe_timeout it set, after it fires, it
returns -ETIMEDOUT
This is a bit confusing, as its useful to have the function
return -EPROBE_DEFER while the timeout is still running. This
behavior has resulted in the somwhat duplicative
driver_deferred_probe_check_state_continue() function being
added.
Thus this patch tries to improve the logic, so that it behaves
as such:
* If late_initcall has passed, and modules are not enabled
it returns -ENODEV
* If modules are enabled and deferred_probe_timeout is set,
it returns -EPROBE_DEFER until the timeout, afterwhich it
returns -ETIMEDOUT.
* In all other cases, it returns -EPROBE_DEFER
This will make the deferred_probe_timeout value much more
functional, and will allow us to consolidate the
driver_deferred_probe_check_state() and
driver_deferred_probe_check_state_continue() logic in a later
patch.
Cc: linux-pm@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200225050828.56458-2-john.stultz@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If a device already has devres items attached before probing, a warning
backtrace is printed. However, this backtrace does not reveal the
offending device, leaving the user uninformed. Furthermore, using
WARN_ON() causes systems with panic-on-warn to reboot.
Fix this by replacing the WARN_ON() by a dev_crit() message.
Abort probing the device, to prevent doing more damage to the device's
resources.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191206132219.28908-1-geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 134b23eec9.
Based on a lot of email and in-person discussions, this patch series is
being reworked to address a number of issues that were pointed out that
needed to be taken care of before it should be merged. It will be
resubmitted with those changes hopefully soon.
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Persistent tag for others to pull this branch from
This is the first patch in a longer series that adds the ability for the
driver core to create and remove a list of attribute groups
automatically when the device is bound/unbound from a specific driver.
See:
https://lore.kernel.org/r/20190731124349.4474-2-gregkh@linuxfoundation.org
for details on this patch, and examples of how to use it in other
drivers.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-----BEGIN PGP SIGNATURE-----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=ioHW
-----END PGP SIGNATURE-----
Merge tag 'dev_groups_all_drivers' into driver-core-next
dev_groups added to struct driver
Persistent tag for others to pull this branch from
This is the first patch in a longer series that adds the ability for the
driver core to create and remove a list of attribute groups
automatically when the device is bound/unbound from a specific driver.
See:
https://lore.kernel.org/r/20190731124349.4474-2-gregkh@linuxfoundation.org
for details on this patch, and examples of how to use it in other
drivers.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add the ability for the driver core to create and remove a list of
attribute groups automatically when the device is bound/unbound from a
specific driver.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: Richard Gong <richard.gong@linux.intel.com>
Link: https://lore.kernel.org/r/20190731124349.4474-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver core/bus adding supplier-consumer dependencies by default
enables functional dependencies to be tracked correctly even when the
consumer devices haven't had their drivers registered or loaded (if they
are modules).
However, when the bus incorrectly adds dependencies that it shouldn't
have added, the devices might never probe.
For example, if device-C is a consumer of device-S and they have
phandles to each other in DT, the following could happen:
1. Device-S get added first.
2. The bus add_links() callback will (incorrectly) try to link it as
a consumer of device-C.
3. Since device-C isn't present, device-S will be put in
"waiting-for-supplier" list.
4. Device-C gets added next.
5. All devices in "waiting-for-supplier" list are retried for linking.
6. Device-S gets linked as consumer to Device-C.
7. The bus add_links() callback will (correctly) try to link it as
a consumer of device-S.
8. This isn't allowed because it would create a cyclic device links.
Neither devices will get probed since the supplier is marked as
dependent on the consumer. And the consumer will never probe because the
consumer can't get resources from the supplier.
Without this patch, things stay in this broken state. However, with this
patch, the execution will continue like this:
9. Device-C's driver is loaded.
10. Device-C's driver removes Device-S as a consumer of Device-C.
11. Device-C's driver adds Device-C as a consumer of Device-S.
12. Device-S probes.
14. Device-C probes.
kbuild test robot reported missing documentation for device.has_edit_links
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20190731221721.187713-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
