s390/pai: rework pai_crypto mapped buffer reference count

Rework the mapped buffer reference count in PMU pai_crypto
to match the same technique as in PMU pai_ext.
This simplifies the logic.
Do not count the individual number of counter and sampling
processes. Remember the type of access and the total number of
references to the buffer.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/perf_pai_crypto.c

@@ -36,8 +36,8 @@ struct paicrypt_map {
 	unsigned long *page;		/* Page for CPU to store counters */
 	struct pai_userdata *save;	/* Page to store no-zero counters */
 	unsigned int users;		/* # of PAI crypto users */
-	unsigned int sampler;		/* # of PAI crypto samplers */
-	unsigned int counter;		/* # of PAI crypto counters */
+	unsigned int refcnt;		/* Reference count mapped buffers */
+	enum paievt_mode mode;		/* Type of event */
 	struct perf_event *event;	/* Perf event for sampling */
 };
 
@@ -56,15 +56,11 @@ static void paicrypt_event_destroy(struct perf_event *event)
 	cpump->event = NULL;
 	static_branch_dec(&pai_key);
 	mutex_lock(&pai_reserve_mutex);
-	if (event->attr.sample_period)
-		cpump->sampler -= 1;
-	else
-		cpump->counter -= 1;
-	debug_sprintf_event(cfm_dbg, 5, "%s event %#llx cpu %d"
-			    " sampler %d counter %d\n", __func__,
-			    event->attr.config, event->cpu, cpump->sampler,
-			    cpump->counter);
-	if (!cpump->counter && !cpump->sampler) {
+	debug_sprintf_event(cfm_dbg, 5, "%s event %#llx cpu %d users %d"
+			    " mode %d refcnt %d\n", __func__,
+			    event->attr.config, event->cpu, cpump->users,
+			    cpump->mode, cpump->refcnt);
+	if (!--cpump->refcnt) {
 		debug_sprintf_event(cfm_dbg, 4, "%s page %#lx save %p\n",
 				    __func__, (unsigned long)cpump->page,
 				    cpump->save);
@@ -72,6 +68,7 @@ static void paicrypt_event_destroy(struct perf_event *event)
 		cpump->page = NULL;
 		kvfree(cpump->save);
 		cpump->save = NULL;
+		cpump->mode = PAI_MODE_NONE;
 	}
 	mutex_unlock(&pai_reserve_mutex);
 }
@@ -136,17 +133,14 @@ static u64 paicrypt_getall(struct perf_event *event)
  */
 static int paicrypt_busy(struct perf_event_attr *a, struct paicrypt_map *cpump)
 {
-	unsigned int *use_ptr;
 	int rc = 0;
 
 	mutex_lock(&pai_reserve_mutex);
 	if (a->sample_period) {		/* Sampling requested */
-		use_ptr = &cpump->sampler;
-		if (cpump->counter || cpump->sampler)
+		if (cpump->mode != PAI_MODE_NONE)
 			rc = -EBUSY;	/* ... sampling/counting active */
 	} else {			/* Counting requested */
-		use_ptr = &cpump->counter;
-		if (cpump->sampler)
+		if (cpump->mode == PAI_MODE_SAMPLING)
 			rc = -EBUSY;	/* ... and sampling active */
 	}
 	if (rc)
@@ -172,12 +166,16 @@ static int paicrypt_busy(struct perf_event_attr *a, struct paicrypt_map *cpump)
 	rc = 0;
 
 unlock:
-	/* If rc is non-zero, do not increment counter/sampler. */
-	if (!rc)
-		*use_ptr += 1;
-	debug_sprintf_event(cfm_dbg, 5, "%s sample_period %#llx sampler %d"
-			    " counter %d page %#lx save %p rc %d\n", __func__,
-			    a->sample_period, cpump->sampler, cpump->counter,
+	/* If rc is non-zero, do not set mode and reference count */
+	if (!rc) {
+		cpump->refcnt++;
+		cpump->mode = a->sample_period ? PAI_MODE_SAMPLING
+					       : PAI_MODE_COUNTING;
+	}
+	debug_sprintf_event(cfm_dbg, 5, "%s sample_period %#llx users %d"
+			    " mode %d refcnt %d page %#lx save %p rc %d\n",
+			    __func__, a->sample_period, cpump->users,
+			    cpump->mode, cpump->refcnt,
 			    (unsigned long)cpump->page, cpump->save, rc);
 	mutex_unlock(&pai_reserve_mutex);
 	return rc;