Re: [PATCH V3 2/8] perf/x86/intel/uncore: Fix refcnt and other cleanups

["Mi, Dapeng" <dapeng1.mi@linux.intel.com>]

LGTM. Thanks.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>

On 6/12/2026 12:00 AM, Zide Chen wrote:
> Fix typo UNCORE_BOX_FLAG_INITIATED to UNCORE_BOX_FLAG_INITIALIZED.
>
> Rename the 'id' parameter in uncore_box_{ref,unref}() to 'die' to
> reflect its actual meaning and be consistent with other functions.
>
> box->refcnt is incremented in the PCI PMU register path but has never
> been checked or decremented. Although for PCI PMUs box->refcnt
> effectively tracks only a single user, add atomic_dec_return() in the
> PCI PMU unregister path to make the reference counting complete and
> consistent.
>
> Signed-off-by: Zide Chen <zide.chen@intel.com>
> ---
> v3:
> - Instead of removing atomic_inc(&box->refcnt) in PMU register, add
>   the corresponding atomic_dec_return(&box->refcnt) in PMU unregister.
>   (Dapeng)
> v2:
> - Don't rename pmu->activeboxes and keep its semantics because in
>   uncore_pci_remove() path, uncore_pci_pmu_unregister() won't be
>   called for non-active boxes.
> - Since pmu->activeboxes keeps its name, don't need to rename
>   box->refcnt to box->cpu_refcnt.
> ---
>  arch/x86/events/intel/uncore.c | 16 +++++++++-------
>  arch/x86/events/intel/uncore.h |  6 +++---
>  2 files changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index b69b6a21d46b..21c8ed1628cb 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -1255,8 +1255,10 @@ static void uncore_pci_pmu_unregister(struct intel_uncore_pmu *pmu, int die)
>  	pmu->boxes[die] = NULL;
>  	if (atomic_dec_return(&pmu->activeboxes) == 0)
>  		uncore_pmu_unregister(pmu);
> -	uncore_box_exit(box);
> -	kfree(box);
> +	if (atomic_dec_return(&box->refcnt) == 0) {
> +		uncore_box_exit(box);
> +		kfree(box);
> +	}
>  }
>  
>  static void uncore_pci_remove(struct pci_dev *pdev)
> @@ -1518,7 +1520,7 @@ static void uncore_change_context(struct intel_uncore_type **uncores,
>  		uncore_change_type_ctx(*uncores, old_cpu, new_cpu);
>  }
>  
> -static void uncore_box_unref(struct intel_uncore_type **types, int id)
> +static void uncore_box_unref(struct intel_uncore_type **types, int die)
>  {
>  	struct intel_uncore_type *type;
>  	struct intel_uncore_pmu *pmu;
> @@ -1529,7 +1531,7 @@ static void uncore_box_unref(struct intel_uncore_type **types, int id)
>  		type = *types;
>  		pmu = type->pmus;
>  		for (i = 0; i < type->num_boxes; i++, pmu++) {
> -			box = pmu->boxes[id];
> +			box = pmu->boxes[die];
>  			if (box && box->cpu >= 0 && atomic_dec_return(&box->refcnt) == 0)
>  				uncore_box_exit(box);
>  		}
> @@ -1604,14 +1606,14 @@ static int allocate_boxes(struct intel_uncore_type **types,
>  }
>  
>  static int uncore_box_ref(struct intel_uncore_type **types,
> -			  int id, unsigned int cpu)
> +			  int die, unsigned int cpu)
>  {
>  	struct intel_uncore_type *type;
>  	struct intel_uncore_pmu *pmu;
>  	struct intel_uncore_box *box;
>  	int i, ret;
>  
> -	ret = allocate_boxes(types, id, cpu);
> +	ret = allocate_boxes(types, die, cpu);
>  	if (ret)
>  		return ret;
>  
> @@ -1619,7 +1621,7 @@ static int uncore_box_ref(struct intel_uncore_type **types,
>  		type = *types;
>  		pmu = type->pmus;
>  		for (i = 0; i < type->num_boxes; i++, pmu++) {
> -			box = pmu->boxes[id];
> +			box = pmu->boxes[die];
>  			if (box && box->cpu >= 0 && atomic_inc_return(&box->refcnt) == 1)
>  				uncore_box_init(box);
>  		}
> diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
> index c2e5ccb1d72c..bad5d8dec8e0 100644
> --- a/arch/x86/events/intel/uncore.h
> +++ b/arch/x86/events/intel/uncore.h
> @@ -185,7 +185,7 @@ struct intel_uncore_box {
>  #define CFL_UNC_CBO_7_PERFEVTSEL0		0xf70
>  #define CFL_UNC_CBO_7_PER_CTR0			0xf76
>  
> -#define UNCORE_BOX_FLAG_INITIATED		0
> +#define UNCORE_BOX_FLAG_INITIALIZED		0
>  /* event config registers are 8-byte apart */
>  #define UNCORE_BOX_FLAG_CTL_OFFS8		1
>  /* CFL 8th CBOX has different MSR space */
> @@ -559,7 +559,7 @@ static inline u64 uncore_read_counter(struct intel_uncore_box *box,
>  
>  static inline void uncore_box_init(struct intel_uncore_box *box)
>  {
> -	if (!test_and_set_bit(UNCORE_BOX_FLAG_INITIATED, &box->flags)) {
> +	if (!test_and_set_bit(UNCORE_BOX_FLAG_INITIALIZED, &box->flags)) {
>  		if (box->pmu->type->ops->init_box)
>  			box->pmu->type->ops->init_box(box);
>  	}
> @@ -567,7 +567,7 @@ static inline void uncore_box_init(struct intel_uncore_box *box)
>  
>  static inline void uncore_box_exit(struct intel_uncore_box *box)
>  {
> -	if (test_and_clear_bit(UNCORE_BOX_FLAG_INITIATED, &box->flags)) {
> +	if (test_and_clear_bit(UNCORE_BOX_FLAG_INITIALIZED, &box->flags)) {
>  		if (box->pmu->type->ops->exit_box)
>  			box->pmu->type->ops->exit_box(box);
>  	}