perf/core: Simplify perf_init_event()

Use the <linux/cleanup.h> guard() and scoped_guard() infrastructure
to simplify the control flow.

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>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20241104135518.302444446@infradead.org

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 215dad53aa1b50e951590cfb9ab75c4085e019b4..fd352361259ca189eeafa7adb345167493d731a5 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12101,10 +12101,10 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
 static struct pmu *perf_init_event(struct perf_event *event)
 {
        bool extended_type = false;
-       int idx, type, ret;
        struct pmu *pmu;
+       int type, ret;
 
-       idx = srcu_read_lock(&pmus_srcu);
+       guard(srcu)(&pmus_srcu);
 
        /*
         * Save original type before calling pmu->event_init() since certain
@@ -12117,7 +12117,7 @@ static struct pmu *perf_init_event(struct perf_event *event)
                pmu = event->parent->pmu;
                ret = perf_try_init_event(pmu, event);
                if (!ret)
-                       goto unlock;
+                       return pmu;
        }
 
        /*
@@ -12136,13 +12136,12 @@ static struct pmu *perf_init_event(struct perf_event *event)
        }
 
 again:
-       rcu_read_lock();
-       pmu = idr_find(&pmu_idr, type);
-       rcu_read_unlock();
+       scoped_guard (rcu)
+               pmu = idr_find(&pmu_idr, type);
        if (pmu) {
                if (event->attr.type != type && type != PERF_TYPE_RAW &&
                    !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
-                       goto fail;
+                       return ERR_PTR(-ENOENT);
 
                ret = perf_try_init_event(pmu, event);
                if (ret == -ENOENT && event->attr.type != type && !extended_type) {
@@ -12151,27 +12150,21 @@ again:
                }
 
                if (ret)
-                       pmu = ERR_PTR(ret);
+                       return ERR_PTR(ret);
 
-               goto unlock;
+               return pmu;
        }
 
        list_for_each_entry_rcu(pmu, &pmus, entry, lockdep_is_held(&pmus_srcu)) {
                ret = perf_try_init_event(pmu, event);
                if (!ret)
-                       goto unlock;
+                       return pmu;
 
-               if (ret != -ENOENT) {
-                       pmu = ERR_PTR(ret);
-                       goto unlock;
-               }
+               if (ret != -ENOENT)
+                       return ERR_PTR(ret);
        }
-fail:
-       pmu = ERR_PTR(-ENOENT);
-unlock:
-       srcu_read_unlock(&pmus_srcu, idx);
 
-       return pmu;
+       return ERR_PTR(-ENOENT);
 }
 
 static void attach_sb_event(struct perf_event *event)