perf: Humanize the number of contexts

Instead of hardcoding the number of contexts for the recursions
barriers, define a cpp constant to make the code more
self-explanatory.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index d7e8ea6..ae6fa60 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -808,6 +808,12 @@ struct perf_event_context {
        struct rcu_head                 rcu_head;
 };
 
+/*
+ * Number of contexts where an event can trigger:
+ *     task, softirq, hardirq, nmi.
+ */
+#define PERF_NR_CONTEXTS       4
+
 /**
  * struct perf_event_cpu_context - per cpu event context structure
  */
@@ -821,12 +827,8 @@ struct perf_cpu_context {
        struct mutex                    hlist_mutex;
        int                             hlist_refcount;
 
-       /*
-        * Recursion avoidance:
-        *
-        * task, softirq, irq, nmi context
-        */
-       int                             recursion[4];
+       /* Recursion avoidance in each contexts */
+       int                             recursion[PERF_NR_CONTEXTS];
 };
 
 struct perf_output_handle {

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 75ab8a2..f416aef 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1772,7 +1772,7 @@ struct callchain_cpus_entries {
        struct perf_callchain_entry     *cpu_entries[0];
 };
 
-static DEFINE_PER_CPU(int, callchain_recursion[4]);
+static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
 static atomic_t nr_callchain_events;
 static DEFINE_MUTEX(callchain_mutex);
 struct callchain_cpus_entries *callchain_cpus_entries;
@@ -1828,7 +1828,7 @@ static int alloc_callchain_buffers(void)
        if (!entries)
                return -ENOMEM;
 
-       size = sizeof(struct perf_callchain_entry) * 4;
+       size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
 
        for_each_possible_cpu(cpu) {
                entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 000e6e8..db2eae2 100644 (file)
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -9,7 +9,7 @@
 #include <linux/kprobes.h>
 #include "trace.h"
 
-static char *perf_trace_buf[4];
+static char *perf_trace_buf[PERF_NR_CONTEXTS];
 
 /*
  * Force it to be aligned to unsigned long to avoid misaligned accesses
@@ -45,7 +45,7 @@ static int perf_trace_event_init(struct ftrace_event_call *tp_event,
                char *buf;
                int i;
 
-               for (i = 0; i < 4; i++) {
+               for (i = 0; i < PERF_NR_CONTEXTS; i++) {
                        buf = (char *)alloc_percpu(perf_trace_t);
                        if (!buf)
                                goto fail;
@@ -65,7 +65,7 @@ fail:
        if (!total_ref_count) {
                int i;
 
-               for (i = 0; i < 4; i++) {
+               for (i = 0; i < PERF_NR_CONTEXTS; i++) {
                        free_percpu(perf_trace_buf[i]);
                        perf_trace_buf[i] = NULL;
                }
@@ -140,7 +140,7 @@ void perf_trace_destroy(struct perf_event *p_event)
        tp_event->perf_events = NULL;
 
        if (!--total_ref_count) {
-               for (i = 0; i < 4; i++) {
+               for (i = 0; i < PERF_NR_CONTEXTS; i++) {
                        free_percpu(perf_trace_buf[i]);
                        perf_trace_buf[i] = NULL;
                }