linux-kernel - [PATCH 25/35] perf machine: Use realloc_array_as_needed() in machine__set_current

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Message-Id: <20220711093218.10967-26-adrian.hunter@intel.com>
Date:   Mon, 11 Jul 2022 12:32:08 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: [PATCH 25/35] perf machine: Use realloc_array_as_needed() in machine__set_current_tid()

Prepare machine__set_current_tid() for use with guest machines that do
not currently have a machine->env->nr_cpus_avail value by making use of
realloc_array_as_needed().

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/machine.c | 26 +++++++-------------------
 tools/perf/util/machine.h |  1 +
 2 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 009061852808..27d1a38f44c3 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -3174,9 +3174,7 @@ int machines__for_each_thread(struct machines *machines,
 
 pid_t machine__get_current_tid(struct machine *machine, int cpu)
 {
-	int nr_cpus = min(machine->env->nr_cpus_avail, MAX_NR_CPUS);
-
-	if (cpu < 0 || cpu >= nr_cpus || !machine->current_tid)
+	if (cpu < 0 || (size_t)cpu >= machine->current_tid_sz)
 		return -1;
 
 	return machine->current_tid[cpu];
@@ -3186,26 +3184,16 @@ int machine__set_current_tid(struct machine *machine, int cpu, pid_t pid,
 			     pid_t tid)
 {
 	struct thread *thread;
-	int nr_cpus = min(machine->env->nr_cpus_avail, MAX_NR_CPUS);
+	const pid_t init_val = -1;
 
 	if (cpu < 0)
 		return -EINVAL;
 
-	if (!machine->current_tid) {
-		int i;
-
-		machine->current_tid = calloc(nr_cpus, sizeof(pid_t));
-		if (!machine->current_tid)
-			return -ENOMEM;
-		for (i = 0; i < nr_cpus; i++)
-			machine->current_tid[i] = -1;
-	}
-
-	if (cpu >= nr_cpus) {
-		pr_err("Requested CPU %d too large. ", cpu);
-		pr_err("Consider raising MAX_NR_CPUS\n");
-		return -EINVAL;
-	}
+	if (realloc_array_as_needed(machine->current_tid,
+				    machine->current_tid_sz,
+				    (unsigned int)cpu,
+				    &init_val))
+		return -ENOMEM;
 
 	machine->current_tid[cpu] = tid;
 
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index d40b23c71420..609e24e329d1 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -57,6 +57,7 @@ struct machine {
 	struct map	  *vmlinux_map;
 	u64		  kernel_start;
 	pid_t		  *current_tid;
+	size_t		  current_tid_sz;
 	union { /* Tool specific area */
 		void	  *priv;
 		u64	  db_id;
-- 
2.25.1