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The configfs system is a source of access to the config information in the
configuration and feature lists.
This can result in additional LOCKDEP issues as a result of the mutex
ordering between the config list mutex (cscfg_mutex) and the configfs
system mutexes.
As such we need to adjust how load/unload operations work to ensure correct
operation.
1) Previously the cscfg_mutex was held throughout the load/unload
operation. This is now only held during configuration list manipulations,
resulting in a multi-stage load/unload process.
2) All operations that manipulate the configfs representation of the
configurations and features are now separated out and run without the
cscfg_mutex being held. This avoids circular lock_dep issue with the
built-in configfs mutexes and semaphores
3) As the load and unload is now multi-stage, some parts under the
cscfg_mutex and others not:
i) A flag indicating a load / unload operation in progress is used to
serialise load / unload operations.
ii) activating any configuration not possible when unload is in progress.
iii) Configurations have an "available" flag set only after the last load
stage for the configuration is complete. Activation of the configuration
not possible till flag is set.
4) Following load/unload rules remain:
i) Unload prevented while any configuration is active remains.
ii) Unload in strict reverse order of load.
iii) Existing configurations can be activated while a new load operation
is underway. (by definition there can be no dependencies between an
existing configuration and a new loading one due to ii) above.)
Fixes: eb2ec49606c2 ("coresight: syscfg: Update load API for config loadable modules")
Reported-by: Suzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-and-tested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220628173004.30002-3-mike.leach@linaro.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Any loaded configurations must be correctly unloaded on coresight module
exit, or issues can arise with nested locking in the configfs directory
code if built with CONFIG_LOCKDEP.
Prior to this patch, the preloaded configuration configfs directory entries
were being unloaded by the recursive code in
configfs_unregister_subsystem().
However, when built with CONFIG_LOCKDEP, this caused a nested lock warning,
which was not mitigated by the LOCKDEP dependent code in fs/configfs/dir.c
designed to prevent this, due to the different directory levels for the
root of the directory being removed.
As the preloaded (and all other) configurations are registered after
configfs_register_subsystem(), we now explicitly unload them before the
call to configfs_unregister_subsystem().
The new routine cscfg_unload_cfgs_on_exit() iterates through the load
owner list to unload any remaining configurations that were not unloaded
by the user before the module exits. This covers both the
CSCFG_OWNER_PRELOAD and CSCFG_OWNER_MODULE owner types, and will be
extended to cover future load owner types for CoreSight configurations.
Fixes: eb2ec49606c2 ("coresight: syscfg: Update load API for config loadable modules")
Reported-by: Suzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-and-tested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220628173004.30002-2-mike.leach@linaro.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
device_register() calls device_initialize(),
according to doc of device_initialize:
Use put_device() to give up your reference instead of freeing
* @dev directly once you have called this function.
To prevent potential memleak, use put_device() for error handling.
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Fixes: 85e2414c518a ("coresight: syscfg: Initial coresight system configuration")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220124124121.8888-1-linmq006@gmail.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Adds configfs attributes to allow a configuration to be enabled for use
when sysfs is used to control CoreSight.
perf retains independent enabling of configurations.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20211124200038.28662-6-mike.leach@linaro.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
CoreSight configurations and features can be added as kernel loadable
modules. This patch updates the load owner API to ensure that the module
cannot be unloaded either:
1) if the config it supplies is in use
2) if the module is not the last in the load order list.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20211124200038.28662-4-mike.leach@linaro.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Expand the configuration API to allow dynamic runtime load and unload of
configurations and features.
On load, configurations and features are tagged with a "load owner" that
is used to determine sets that were loaded together in a given API call.
To unload the API uses the load owner to unload all elements previously
loaded by that owner.
The API also records the order in which different owners loaded
their elements into the system. Later loading configurations can use
previously loaded features, creating load dependencies. Therefore unload
is enforced strictly in the reverse order to load.
A load owner will be an additional loadable module, or a configuration
loaded via configfs.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20211124200038.28662-3-mike.leach@linaro.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Update the existing load API to introduce a "load owner" concept.
This allows the tracking of the loaded configurations and features against
the loading owner type, to allow later unload according to owner.
A list of loaded configurations by owner is created.
The load owner infrastructure will be used in following patches
to implement dynanic load and unload, alongside dependency tracking.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20211124200038.28662-2-mike.leach@linaro.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Adds configfs subsystem and attributes to the configuration manager
to enable the listing of loaded configurations and features.
The default values of feature parameters can be accessed and altered
from these attributes to affect all installed devices using the feature.
Link: https://lore.kernel.org/r/20210723165444.1048-10-mike.leach@linaro.org
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210818194022.379573-10-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Preload set of configurations.
This patch creates a small set of preloaded configurations and features
that are available immediately after coresight has been initialised.
The current set provides a strobing feature for ETMv4, that creates a
periodic sampling of trace by switching trace generation on and off
using counters in the ETM.
A configuration called "autofdo" is also provided that uses the 'strobing'
feature and provides a couple of preset values, selectable on the perf
command line.
Link: https://lore.kernel.org/r/20210723165444.1048-9-mike.leach@linaro.org
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210818194022.379573-9-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
API for individual devices to register with the syscfg management
system is added.
Devices register with matching information, and any features or
configurations that match will be loaded into the device.
The feature and configuration loading is extended so that on load these
are loaded into any currently registered devices. This allows
configuration loading after devices have been registered.
Link: https://lore.kernel.org/r/20210723165444.1048-3-mike.leach@linaro.org
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210818194022.379573-3-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Creates an system management API to allow complex configurations and
features to be programmed into a CoreSight infrastructure.
A feature is defined as a programming set for a device or class of
devices.
A configuration is a set of features across the system that are enabled
for a trace session.
The API will manage system wide configuration, and allow complex
programmed features to be added to individual device instances, and
provide for system wide configuration selection on trace capture
operations.
This patch creates the initial data object and the initial API for
loading configurations and features.
Link: https://lore.kernel.org/r/20210723165444.1048-2-mike.leach@linaro.org
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210818194022.379573-2-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
