Commit 6c8b0b83 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf/core: Simplify perf_pmu_register() 



Using the previously introduced perf_pmu_free() and a new IDR helper,
simplify the perf_pmu_register error paths.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarRavi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20241104135518.198937277@infradead.org
parent 8f4c4963

include/linux/idr.h

+17 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/radix-tree.h>

#include <linux/gfp.h>

#include <linux/percpu.h>

#include <linux/cleanup.h>



struct idr {

	struct radix_tree_root	idr_rt;
@@ -124,6 +125,22 @@ void *idr_get_next_ul(struct idr *, unsigned long *nextid); 
void *idr_replace(struct idr *, void *, unsigned long id);

void idr_destroy(struct idr *);



struct __class_idr {

	struct idr *idr;

	int id;

};



#define idr_null ((struct __class_idr){ NULL, -1 })

#define take_idr_id(id) __get_and_null(id, idr_null)



DEFINE_CLASS(idr_alloc, struct __class_idr,

	     if (_T.id >= 0) idr_remove(_T.idr, _T.id),

	     ((struct __class_idr){

	     	.idr = idr,

		.id = idr_alloc(idr, ptr, start, end, gfp),

	     }),

	     struct idr *idr, void *ptr, int start, int end, gfp_t gfp);



/**

 * idr_init_base() - Initialise an IDR.

 * @idr: IDR handle.

kernel/events/core.c

+29 −42
Original line number Diff line number Diff line
@@ -11914,52 +11914,49 @@ static void perf_pmu_free(struct pmu *pmu) 
	free_percpu(pmu->cpu_pmu_context);

}



int perf_pmu_register(struct pmu *pmu, const char *name, int type)

DEFINE_FREE(pmu_unregister, struct pmu *, if (_T) perf_pmu_free(_T))



int perf_pmu_register(struct pmu *_pmu, const char *name, int type)

{

	int cpu, ret, max = PERF_TYPE_MAX;

	int cpu, max = PERF_TYPE_MAX;



	pmu->type = -1;

	struct pmu *pmu __free(pmu_unregister) = _pmu;

	guard(mutex)(&pmus_lock);



	mutex_lock(&pmus_lock);

	ret = -ENOMEM;

	pmu->pmu_disable_count = alloc_percpu(int);

	if (!pmu->pmu_disable_count)

		goto unlock;

		return -ENOMEM;



	if (WARN_ONCE(!name, "Can not register anonymous pmu.\n")) {

		ret = -EINVAL;

		goto free;

	}

	if (WARN_ONCE(!name, "Can not register anonymous pmu.\n"))

		return -EINVAL;



	if (WARN_ONCE(pmu->scope >= PERF_PMU_MAX_SCOPE, "Can not register a pmu with an invalid scope.\n")) {

		ret = -EINVAL;

		goto free;

	}

	if (WARN_ONCE(pmu->scope >= PERF_PMU_MAX_SCOPE,

		      "Can not register a pmu with an invalid scope.\n"))

		return -EINVAL;



	pmu->name = name;



	if (type >= 0)

		max = type;



	ret = idr_alloc(&pmu_idr, NULL, max, 0, GFP_KERNEL);

	if (ret < 0)

		goto free;

	CLASS(idr_alloc, pmu_type)(&pmu_idr, NULL, max, 0, GFP_KERNEL);

	if (pmu_type.id < 0)

		return pmu_type.id;



	WARN_ON(type >= 0 && ret != type);

	WARN_ON(type >= 0 && pmu_type.id != type);



	pmu->type = ret;

	pmu->type = pmu_type.id;

	atomic_set(&pmu->exclusive_cnt, 0);



	if (pmu_bus_running && !pmu->dev) {

		ret = pmu_dev_alloc(pmu);

		int ret = pmu_dev_alloc(pmu);

		if (ret)

			goto free;

			return ret;

	}



	ret = -ENOMEM;

	pmu->cpu_pmu_context = alloc_percpu(struct perf_cpu_pmu_context);

	if (!pmu->cpu_pmu_context)

		goto free;

		return -ENOMEM;



	for_each_possible_cpu(cpu) {

		struct perf_cpu_pmu_context *cpc;
@@ -12000,32 +11997,22 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type) 
	/*

	 * Now that the PMU is complete, make it visible to perf_try_init_event().

	 */

	if (!idr_cmpxchg(&pmu_idr, pmu->type, NULL, pmu)) {

		ret = -EINVAL;

		goto free;

	}

	if (!idr_cmpxchg(&pmu_idr, pmu->type, NULL, pmu))

		return -EINVAL;

	list_add_rcu(&pmu->entry, &pmus);



	ret = 0;

unlock:

	mutex_unlock(&pmus_lock);



	return ret;



free:

	if (pmu->type >= 0)

		idr_remove(&pmu_idr, pmu->type);

	perf_pmu_free(pmu);

	goto unlock;

	take_idr_id(pmu_type);

	_pmu = no_free_ptr(pmu); // let it rip

	return 0;

}

EXPORT_SYMBOL_GPL(perf_pmu_register);



void perf_pmu_unregister(struct pmu *pmu)

{

	mutex_lock(&pmus_lock);

	scoped_guard (mutex, &pmus_lock) {

		list_del_rcu(&pmu->entry);

		idr_remove(&pmu_idr, pmu->type);

	mutex_unlock(&pmus_lock);

	}



	/*

	 * We dereference the pmu list under both SRCU and regular RCU, so