[PATCH v7 09/25] coresight: etm3x: allow etm3x to be built as a module
Sai Prakash Ranjan
saiprakash.ranjan at codeaurora.org
Thu Aug 6 01:44:56 EDT 2020
Hi Mike,
On 2020-08-05 18:24, Mike Leach wrote:
> Hi,
>
> On Wed, 5 Aug 2020 at 12:05, Suzuki K Poulose <suzuki.poulose at arm.com>
> wrote:
>>
>> On 08/05/2020 03:54 AM, Tingwei Zhang wrote:
>> > From: Kim Phillips <kim.phillips at arm.com>
>> >
>> > Allow to build coresight-etm3x as a module, for ease of development.
>> >
>> > - Kconfig becomes a tristate, to allow =m
>> > - append -core to source file name to allow module to
>> > be called coresight-etm3x by the Makefile
>> > - add an etm_remove function, for module unload
>> > - add a MODULE_DEVICE_TABLE for autoloading on boot
>> >
>> > Cc: Mathieu Poirier <mathieu.poirier at linaro.org>
>> > Cc: Leo Yan <leo.yan at linaro.org>
>> > Cc: Alexander Shishkin <alexander.shishkin at linux.intel.com>
>> > Cc: Randy Dunlap <rdunlap at infradead.org>
>> > Cc: Suzuki K Poulose <Suzuki.Poulose at arm.com>
>> > Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
>> > Cc: Russell King <linux at armlinux.org.uk>
>> > Signed-off-by: Kim Phillips <kim.phillips at arm.com>
>> > Signed-off-by: Tingwei Zhang <tingwei at codeaurora.org>
>> > Reviewed-by: Mike Leach <mike.leach at linaro.org>
>> > ---
>> > drivers/hwtracing/coresight/Kconfig | 5 +++-
>> > drivers/hwtracing/coresight/Makefile | 3 ++-
>> > ...resight-etm3x.c => coresight-etm3x-core.c} | 27 ++++++++++++++++++-
>> > 3 files changed, 32 insertions(+), 3 deletions(-)
>> > rename drivers/hwtracing/coresight/{coresight-etm3x.c => coresight-etm3x-core.c} (97%)
>> >
>> > diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
>> > index 6433f835fc97..8fd9fd139cf3 100644
>> > --- a/drivers/hwtracing/coresight/Kconfig
>> > +++ b/drivers/hwtracing/coresight/Kconfig
>> > @@ -65,7 +65,7 @@ config CORESIGHT_SINK_ETBV10
>> > special enhancement or added features.
>> >
>> > config CORESIGHT_SOURCE_ETM3X
>> > - bool "CoreSight Embedded Trace Macrocell 3.x driver"
>> > + tristate "CoreSight Embedded Trace Macrocell 3.x driver"
>> > depends on !ARM64
>> > select CORESIGHT_LINKS_AND_SINKS
>> > help
>> > @@ -74,6 +74,9 @@ config CORESIGHT_SOURCE_ETM3X
>> > This is primarily useful for instruction level tracing. Depending
>> > the ETM version data tracing may also be available.
>> >
>> > + To compile this driver as a module, choose M here: the
>> > + module will be called coresight-etm3x.
>> > +
>> > config CORESIGHT_SOURCE_ETM4X
>> > bool "CoreSight Embedded Trace Macrocell 4.x driver"
>> > depends on ARM64
>> > diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
>> > index 19497d1d92bf..d619cfd0abd8 100644
>> > --- a/drivers/hwtracing/coresight/Makefile
>> > +++ b/drivers/hwtracing/coresight/Makefile
>> > @@ -11,7 +11,8 @@ obj-$(CONFIG_CORESIGHT_SINK_TPIU) += coresight-tpiu.o
>> > obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
>> > obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
>> > coresight-replicator.o
>> > -obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o coresight-etm-cp14.o \
>> > +obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o
>> > +coresight-etm3x-y := coresight-etm3x-core.o coresight-etm-cp14.o \
>> > coresight-etm3x-sysfs.o
>> > obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
>> > coresight-etm4x-sysfs.o
>> > diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
>> > similarity index 97%
>> > rename from drivers/hwtracing/coresight/coresight-etm3x.c
>> > rename to drivers/hwtracing/coresight/coresight-etm3x-core.c
>> > index bf22dcfd3327..82b333c40006 100644
>> > --- a/drivers/hwtracing/coresight/coresight-etm3x.c
>> > +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
>> > @@ -895,6 +895,23 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
>> > return ret;
>> > }
>> >
>> > +static int __exit etm_remove(struct amba_device *adev)
>> > +{
>> > + struct etm_drvdata *drvdata = dev_get_drvdata(&adev->dev);
>> > +
>> > + etm_perf_symlink(drvdata->csdev, false);
>> > +
>> > + if (--etm_count == 0) {
>>
>> Could there be multiple instances of remove running in parallel ? I
>> believe we need some sort of a protection here to avoid racing.
>>
>> Or even better, I would recommend leaving the notifiers registered
>> at module_init and removed at the cleanup of the module, just like
>> we are doing for etm4x driver, and get rid of this silly scheme.
>
> I would agree that this needs addressing but this is an independent
> problem that could be better served by a separate patchset, rather
> than add feature creep to this set. The same schema is used in the CTI
> driver as well and needs fixing there.
>
>> Like here :
>>
>> https://lkml.kernel.org/r/20200729051310.18436-1-saiprakash.ranjan@codeaurora.org
>>
>
> This conflicts with the init / exit fns created for module loading in
> the etm4x part of this set..
>
> A decision needs to be made on which set gets applied first - my view
> is that the module set could go first, then a set fixing the PM
> registration issues for all three affected drivers to be applied next.
The etm4_count race is a bug fix which in my opinion should go first
because
this feature would likely to be merged for 5.10 and till then we would
have
a bug lying around if the fix patch for the race does not go in right?
Thanks,
Sai
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