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perf/core: Simplify the perf_event_alloc() error path

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The error cleanup sequence in perf_event_alloc() is a subset of the
existing _free_event() function (it must of course be).

Split this out into __free_event() and simplify the error path.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20241104135517.967889521@infradead.org
This commit is contained in:
Peter Zijlstra 2024-11-04 14:39:13 +01:00 • committed by Ingo Molnar
parent 061c991697
commit c70ca29803
2 changed files with 79 additions and 77 deletions
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16
include/linux/perf_event.h
View file

@ -673,13 +673,15 @@ struct swevent_hlist {
struct rcu_head rcu_head;
};
#define PERF_ATTACH_CONTEXT 0x01
#define PERF_ATTACH_GROUP 0x02
#define PERF_ATTACH_TASK 0x04
#define PERF_ATTACH_TASK_DATA 0x08
#define PERF_ATTACH_ITRACE 0x10
#define PERF_ATTACH_SCHED_CB 0x20
#define PERF_ATTACH_CHILD 0x40
#define PERF_ATTACH_CONTEXT 0x0001
#define PERF_ATTACH_GROUP 0x0002
#define PERF_ATTACH_TASK 0x0004
#define PERF_ATTACH_TASK_DATA 0x0008
#define PERF_ATTACH_ITRACE 0x0010
#define PERF_ATTACH_SCHED_CB 0x0020
#define PERF_ATTACH_CHILD 0x0040
#define PERF_ATTACH_EXCLUSIVE 0x0080
#define PERF_ATTACH_CALLCHAIN 0x0100
struct bpf_prog;
struct perf_cgroup;

140
kernel/events/core.c
View file

@ -5289,6 +5289,8 @@ static int exclusive_event_init(struct perf_event *event)
return -EBUSY;
}
event->attach_state |= PERF_ATTACH_EXCLUSIVE;
return 0;
}
@ -5296,14 +5298,13 @@ static void exclusive_event_destroy(struct perf_event *event)
{
struct pmu *pmu = event->pmu;
if (!is_exclusive_pmu(pmu))
return;
/* see comment in exclusive_event_init() */
if (event->attach_state & PERF_ATTACH_TASK)
atomic_dec(&pmu->exclusive_cnt);
else
atomic_inc(&pmu->exclusive_cnt);
event->attach_state &= ~PERF_ATTACH_EXCLUSIVE;
}
static bool exclusive_event_match(struct perf_event *e1, struct perf_event *e2)
@ -5362,6 +5363,54 @@ static void perf_pending_task_sync(struct perf_event *event)
rcuwait_wait_event(&event->pending_work_wait, !event->pending_work, TASK_UNINTERRUPTIBLE);
}
/* vs perf_event_alloc() error */
static void __free_event(struct perf_event *event)
{
if (event->attach_state & PERF_ATTACH_CALLCHAIN)
put_callchain_buffers();
kfree(event->addr_filter_ranges);
if (event->attach_state & PERF_ATTACH_EXCLUSIVE)
exclusive_event_destroy(event);
if (is_cgroup_event(event))
perf_detach_cgroup(event);
if (event->destroy)
event->destroy(event);
/*
* Must be after ->destroy(), due to uprobe_perf_close() using
* hw.target.
*/
if (event->hw.target)
put_task_struct(event->hw.target);
if (event->pmu_ctx) {
/*
* put_pmu_ctx() needs an event->ctx reference, because of
* epc->ctx.
*/
WARN_ON_ONCE(!event->ctx);
WARN_ON_ONCE(event->pmu_ctx->ctx != event->ctx);
put_pmu_ctx(event->pmu_ctx);
}
/*
* perf_event_free_task() relies on put_ctx() being 'last', in
* particular all task references must be cleaned up.
*/
if (event->ctx)
put_ctx(event->ctx);
if (event->pmu)
module_put(event->pmu->module);
call_rcu(&event->rcu_head, free_event_rcu);
}
/* vs perf_event_alloc() success */
static void _free_event(struct perf_event *event)
{
irq_work_sync(&event->pending_irq);
@ -5384,42 +5433,10 @@ static void _free_event(struct perf_event *event)
mutex_unlock(&event->mmap_mutex);
}
if (is_cgroup_event(event))
perf_detach_cgroup(event);
if (!event->parent) {
if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
put_callchain_buffers();
}
perf_event_free_bpf_prog(event);
perf_addr_filters_splice(event, NULL);
kfree(event->addr_filter_ranges);
if (event->destroy)
event->destroy(event);
/*
* Must be after ->destroy(), due to uprobe_perf_close() using
* hw.target.
*/
if (event->hw.target)
put_task_struct(event->hw.target);
if (event->pmu_ctx)
put_pmu_ctx(event->pmu_ctx);
/*
* perf_event_free_task() relies on put_ctx() being 'last', in particular
* all task references must be cleaned up.
*/
if (event->ctx)
put_ctx(event->ctx);
exclusive_event_destroy(event);
module_put(event->pmu->module);
call_rcu(&event->rcu_head, free_event_rcu);
__free_event(event);
}
/*
@ -12093,8 +12110,10 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
event->destroy(event);
}
if (ret)
if (ret) {
event->pmu = NULL;
module_put(pmu->module);
}
return ret;
}
@ -12422,7 +12441,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
* See perf_output_read().
*/
if (has_inherit_and_sample_read(attr) && !(attr->sample_type & PERF_SAMPLE_TID))
goto err_ns;
goto err;
if (!has_branch_stack(event))
event->attr.branch_sample_type = 0;
@ -12430,7 +12449,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
pmu = perf_init_event(event);
if (IS_ERR(pmu)) {
err = PTR_ERR(pmu);
goto err_ns;
goto err;
}
/*
@ -12440,25 +12459,25 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
*/
if (pmu->task_ctx_nr == perf_invalid_context && (task || cgroup_fd != -1)) {
err = -EINVAL;
goto err_pmu;
goto err;
}
if (event->attr.aux_output &&
(!(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT) ||
event->attr.aux_pause || event->attr.aux_resume)) {
err = -EOPNOTSUPP;
goto err_pmu;
goto err;
}
if (event->attr.aux_pause && event->attr.aux_resume) {
err = -EINVAL;
goto err_pmu;
goto err;
}
if (event->attr.aux_start_paused) {
if (!(pmu->capabilities & PERF_PMU_CAP_AUX_PAUSE)) {
err = -EOPNOTSUPP;
goto err_pmu;
goto err;
}
event->hw.aux_paused = 1;
}
@ -12466,12 +12485,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
if (cgroup_fd != -1) {
err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
if (err)
goto err_pmu;
goto err;
}
err = exclusive_event_init(event);
if (err)
goto err_pmu;
goto err;
if (has_addr_filter(event)) {
event->addr_filter_ranges = kcalloc(pmu->nr_addr_filters,
@ -12479,7 +12498,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
GFP_KERNEL);
if (!event->addr_filter_ranges) {
err = -ENOMEM;
goto err_per_task;
goto err;
}
/*
@ -12504,41 +12523,22 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
err = get_callchain_buffers(attr->sample_max_stack);
if (err)
goto err_addr_filters;
goto err;
event->attach_state |= PERF_ATTACH_CALLCHAIN;
}
}
err = security_perf_event_alloc(event);
if (err)
goto err_callchain_buffer;
goto err;
/* symmetric to unaccount_event() in _free_event() */
account_event(event);
return event;
err_callchain_buffer:
if (!event->parent) {
if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
put_callchain_buffers();
}
err_addr_filters:
kfree(event->addr_filter_ranges);
err_per_task:
exclusive_event_destroy(event);
err_pmu:
if (is_cgroup_event(event))
perf_detach_cgroup(event);
if (event->destroy)
event->destroy(event);
module_put(pmu->module);
err_ns:
if (event->hw.target)
put_task_struct(event->hw.target);
call_rcu(&event->rcu_head, free_event_rcu);
err:
__free_event(event);
return ERR_PTR(err);
}