[Intel-gfx] [PATCH 1/2] drm/i915/perf: Register sysctl path globally

[Venkata Sandeep Dhanalakota]

On 19/12/12 01:34, Lucas De Marchi wrote:
> On Wed, Dec 11, 2019 at 11:35:21PM -0800, Venkata Sandeep Dhanalakota wrote:
> > We do not require to register the sysctl paths per instance,
> > so making registration global.
> > 
> > v2: make sysctl path register and unregister function driver
> >    specific (Tvrtko and Lucas).
> > 
> > Cc: Sudeep Dutt <sudeep.dutt at intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Jani Nikula <jani.nikula at intel.com>
> > Signed-off-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota at intel.com>
> > ---
> > drivers/gpu/drm/i915/i915_pci.c        |  6 ++++++
> > drivers/gpu/drm/i915/i915_perf.c       | 19 ++++++++++++++++---
> > drivers/gpu/drm/i915/i915_perf.h       |  2 ++
> > drivers/gpu/drm/i915/i915_perf_types.h |  1 -
> > 4 files changed, 24 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
> > index bba6b50e6beb..c5a2bb5e87fe 100644
> > --- a/drivers/gpu/drm/i915/i915_pci.c
> > +++ b/drivers/gpu/drm/i915/i915_pci.c
> > @@ -30,6 +30,7 @@
> > #include "display/intel_fbdev.h"
> > 
> > #include "i915_drv.h"
> > +#include "i915_perf.h"
> > #include "i915_globals.h"
> > #include "i915_selftest.h"
> > 
> > @@ -1051,6 +1052,10 @@ static int __init i915_init(void)
> > 		return 0;
> > 	}
> > 
> > +	err = i915_perf_sysctl_register();
> > +	if (err)
> > +		return err;
> > +
> > 	return pci_register_driver(&i915_pci_driver);
> > }
> > 
> > @@ -1059,6 +1064,7 @@ static void __exit i915_exit(void)
> > 	if (!i915_pci_driver.driver.owner)
> > 		return;
> > 
> > +	i915_perf_sysctl_unregister();
> 
> honoring  the init order means to unregister this after
> pci_unregister_driver()
I think we should reverse the init order, because if we cannot
register pci driver successfully then we dont need to register
sysctl table.

> 
> > 	pci_unregister_driver(&i915_pci_driver);
> > 	i915_globals_exit();
> > }
> > diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> > index 8d2e37949f46..f039beed1771 100644
> > --- a/drivers/gpu/drm/i915/i915_perf.c
> > +++ b/drivers/gpu/drm/i915/i915_perf.c
> > @@ -387,6 +387,8 @@ struct i915_oa_config_bo {
> > 	struct i915_vma *vma;
> > };
> > 
> > +static struct ctl_table_header *sysctl_header;
> > +
> > static enum hrtimer_restart oa_poll_check_timer_cb(struct hrtimer *hrtimer);
> > 
> > void i915_oa_config_release(struct kref *ref)
> > @@ -4345,7 +4347,6 @@ void i915_perf_init(struct drm_i915_private *i915)
> > 
> > 		oa_sample_rate_hard_limit = 1000 *
> > 			(RUNTIME_INFO(i915)->cs_timestamp_frequency_khz / 2);
> > -		perf->sysctl_header = register_sysctl_table(dev_root);
> 
> doc for this function also needs an update with
> s/module load/module bind/
sure.
> 
> > 
> > 		mutex_init(&perf->metrics_lock);
> > 		idr_init(&perf->metrics_idr);
> > @@ -4381,6 +4382,20 @@ static int destroy_config(int id, void *p, void *data)
> > 	return 0;
> > }
> > 
> > +int i915_perf_sysctl_register(void)
> > +{
> > +	sysctl_header = register_sysctl_table(dev_root);
> > +	if (!sysctl_header)
> > +		return -ENOMEM;
> 
> Not sure about this return code here. grepping other drivers, this seems
> to be common, but checking register_sysctl_table() it can actually fail
> for other reasons.
> 
> The previous behavior was to ignore it and not fail the entire thing...
> just living without this sysctl. I'd say to keep that behavior.
> 
Sure, we could ignore the return code for now.
> Lucas De Marchi
> 
> > +
> > +	return 0;
> > +}
> > +
> > +void i915_perf_sysctl_unregister(void)
> > +{
> > +	unregister_sysctl_table(sysctl_header);
> > +}
> > +
> > /**
> >  * i915_perf_fini - Counter part to i915_perf_init()
> >  * @i915: i915 device instance
> > @@ -4395,8 +4410,6 @@ void i915_perf_fini(struct drm_i915_private *i915)
> > 	idr_for_each(&perf->metrics_idr, destroy_config, perf);
> > 	idr_destroy(&perf->metrics_idr);
> > 
> > -	unregister_sysctl_table(perf->sysctl_header);
> > -
> > 	memset(&perf->ops, 0, sizeof(perf->ops));
> > 	perf->i915 = NULL;
> > }
> > diff --git a/drivers/gpu/drm/i915/i915_perf.h b/drivers/gpu/drm/i915/i915_perf.h
> > index 4ceebce72060..1d1329e5af3a 100644
> > --- a/drivers/gpu/drm/i915/i915_perf.h
> > +++ b/drivers/gpu/drm/i915/i915_perf.h
> > @@ -23,6 +23,8 @@ void i915_perf_fini(struct drm_i915_private *i915);
> > void i915_perf_register(struct drm_i915_private *i915);
> > void i915_perf_unregister(struct drm_i915_private *i915);
> > int i915_perf_ioctl_version(void);
> > +int i915_perf_sysctl_register(void);
> > +void i915_perf_sysctl_unregister(void);
> > 
> > int i915_perf_open_ioctl(struct drm_device *dev, void *data,
> > 			 struct drm_file *file);
> > diff --git a/drivers/gpu/drm/i915/i915_perf_types.h b/drivers/gpu/drm/i915/i915_perf_types.h
> > index 74ddc20a0d37..45e581455f5d 100644
> > --- a/drivers/gpu/drm/i915/i915_perf_types.h
> > +++ b/drivers/gpu/drm/i915/i915_perf_types.h
> > @@ -380,7 +380,6 @@ struct i915_perf {
> > 	struct drm_i915_private *i915;
> > 
> > 	struct kobject *metrics_kobj;
> > -	struct ctl_table_header *sysctl_header;
> > 
> > 	/*
> > 	 * Lock associated with adding/modifying/removing OA configs
> > -- 
> > 2.21.0.5.gaeb582a983
> > 
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