s390/pai_ext: replace atomic_t with refcount_t

The s390 PMU of PAI extension 1 NNPA counters uses atomic_t for
reference counting. Replace this with the proper data type
refcount_t.

No functional change.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/arch/s390/kernel/perf_pai_ext.c b/arch/s390/kernel/perf_pai_ext.c
index fcea307..3b4f384 100644 (file)
--- a/arch/s390/kernel/perf_pai_ext.c
+++ b/arch/s390/kernel/perf_pai_ext.c
@@ -50,7 +50,7 @@ struct paiext_map {
        struct pai_userdata *save;      /* Area to store non-zero counters */
        enum paievt_mode mode;          /* Type of event */
        unsigned int active_events;     /* # of PAI Extension users */
-       unsigned int refcnt;
+       refcount_t refcnt;
        struct perf_event *event;       /* Perf event for sampling */
        struct paiext_cb *paiext_cb;    /* PAI extension control block area */
 };
@@ -60,14 +60,14 @@ struct paiext_mapptr {
 };
 
 static struct paiext_root {            /* Anchor to per CPU data */
-       int refcnt;                     /* Overall active events */
+       refcount_t refcnt;              /* Overall active events */
        struct paiext_mapptr __percpu *mapptr;
 } paiext_root;
 
 /* Free per CPU data when the last event is removed. */
 static void paiext_root_free(void)
 {
-       if (!--paiext_root.refcnt) {
+       if (refcount_dec_and_test(&paiext_root.refcnt)) {
                free_percpu(paiext_root.mapptr);
                paiext_root.mapptr = NULL;
        }
@@ -80,7 +80,7 @@ static void paiext_root_free(void)
  */
 static int paiext_root_alloc(void)
 {
-       if (++paiext_root.refcnt == 1) {
+       if (!refcount_inc_not_zero(&paiext_root.refcnt)) {
                /* The memory is already zeroed. */
                paiext_root.mapptr = alloc_percpu(struct paiext_mapptr);
                if (!paiext_root.mapptr) {
@@ -91,6 +91,7 @@ static int paiext_root_alloc(void)
                         */
                        return -ENOMEM;
                }
+               refcount_set(&paiext_root.refcnt, 1);
        }
        return 0;
 }
@@ -122,7 +123,7 @@ static void paiext_event_destroy(struct perf_event *event)
 
        mutex_lock(&paiext_reserve_mutex);
        cpump->event = NULL;
-       if (!--cpump->refcnt)           /* Last reference gone */
+       if (refcount_dec_and_test(&cpump->refcnt))      /* Last reference gone */
                paiext_free(mp);
        paiext_root_free();
        mutex_unlock(&paiext_reserve_mutex);
@@ -163,7 +164,7 @@ static int paiext_alloc(struct perf_event_attr *a, struct perf_event *event)
                rc = -ENOMEM;
                cpump = kzalloc(sizeof(*cpump), GFP_KERNEL);
                if (!cpump)
-                       goto unlock;
+                       goto undo;
 
                /* Allocate memory for counter area and counter extraction.
                 * These are
@@ -183,8 +184,9 @@ static int paiext_alloc(struct perf_event_attr *a, struct perf_event *event)
                                             GFP_KERNEL);
                if (!cpump->save || !cpump->area || !cpump->paiext_cb) {
                        paiext_free(mp);
-                       goto unlock;
+                       goto undo;
                }
+               refcount_set(&cpump->refcnt, 1);
                cpump->mode = a->sample_period ? PAI_MODE_SAMPLING
                                               : PAI_MODE_COUNTING;
        } else {
@@ -195,15 +197,15 @@ static int paiext_alloc(struct perf_event_attr *a, struct perf_event *event)
                if (cpump->mode == PAI_MODE_SAMPLING ||
                    (cpump->mode == PAI_MODE_COUNTING && a->sample_period)) {
                        rc = -EBUSY;
-                       goto unlock;
+                       goto undo;
                }
+               refcount_inc(&cpump->refcnt);
        }
 
        rc = 0;
        cpump->event = event;
-       ++cpump->refcnt;
 
-unlock:
+undo:
        if (rc) {
                /* Error in allocation of event, decrement anchor. Since
                 * the event in not created, its destroy() function is never
@@ -211,6 +213,7 @@ unlock:
                 */
                paiext_root_free();
        }
+unlock:
        mutex_unlock(&paiext_reserve_mutex);
        /* If rc is non-zero, no increment of counter/sampler was done. */
        return rc;