Re: [PATCH 08/11] perf kvm: allow for variable string sizes

[David Ahern]

On 5/5/14, 4:27 AM, Christian Borntraeger wrote:
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 922706c..806c0e4 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -75,7 +75,7 @@ struct kvm_events_ops {
        bool (*is_end_event)(struct perf_evsel *evsel,
                             struct perf_sample *sample, struct event_key *key);
        void (*decode_key)(struct perf_kvm_stat *kvm, struct event_key *key,
-                          char decode[20]);
+                          char *decode);
        const char *name;
  };
@@ -84,6 +84,8 @@ struct exit_reasons_table {
        const char *reason;
  };

+#define DECODE_STR_LEN_MAX 80
+
  #define EVENTS_BITS           12
  #define EVENTS_CACHE_SIZE     (1UL << EVENTS_BITS)

@@ -101,6 +103,8 @@ struct perf_kvm_stat {
        struct exit_reasons_table *exit_reasons;
        const char *exit_reasons_isa;

+       int decode_str_len;
+

This should not be a part of the perf_kvm_stat struct. Just leave it as 
a macro and use DECODE_STR_LEN_MAX in place of 20. Which means 
DECODE_STR_LEN_MAX needs to be 20 in this patch, and arch specific in 
the follow up patch.

        struct kvm_events_ops *events_ops;
        key_cmp_fun compare;
        struct list_head kvm_events_cache[EVENTS_CACHE_SIZE];
@@ -182,12 +186,12 @@ static const char *get_exit_reason(struct perf_kvm_stat 
*kvm,

  static void exit_event_decode_key(struct perf_kvm_stat *kvm,
                                  struct event_key *key,
-                                 char decode[20])
+                                 char *decode)
  {
        const char *exit_reason = get_exit_reason(kvm, kvm->exit_reasons,
                                                  key->key);

-       scnprintf(decode, 20, "%s", exit_reason);
+       scnprintf(decode, kvm->decode_str_len, "%s", exit_reason);
  }

  static struct kvm_events_ops exit_events = {
@@ -249,10 +253,11 @@ static bool mmio_event_end(struct perf_evsel *evsel, 
struct perf_sample *sample,

  static void mmio_event_decode_key(struct perf_kvm_stat *kvm __maybe_unused,
                                  struct event_key *key,
-                                 char decode[20])
+                                 char *decode)
  {
-       scnprintf(decode, 20, "%#lx:%s", (unsigned long)key->key,
-                               key->info == KVM_TRACE_MMIO_WRITE ? "W" : "R");
+       scnprintf(decode, kvm->decode_str_len, "%#lx:%s",
+                 (unsigned long)key->key,
+                 key->info == KVM_TRACE_MMIO_WRITE ? "W" : "R");
  }

  static struct kvm_events_ops mmio_events = {
@@ -292,10 +297,11 @@ static bool ioport_event_end(struct perf_evsel *evsel,

  static void ioport_event_decode_key(struct perf_kvm_stat *kvm __maybe_unused,
                                    struct event_key *key,
-                                   char decode[20])
+                                   char *decode)
  {
-       scnprintf(decode, 20, "%#llx:%s", (unsigned long long)key->key,
-                               key->info ? "POUT" : "PIN");
+       scnprintf(decode, kvm->decode_str_len, "%#llx:%s",
+                 (unsigned long long)key->key,
+                 key->info ? "POUT" : "PIN");
  }

  static struct kvm_events_ops ioport_events = {
@@ -523,13 +529,13 @@ static bool handle_end_event(struct perf_kvm_stat *kvm,
        time_diff = sample->time - time_begin;

        if (kvm->duration && time_diff > kvm->duration) {
-               char decode[32];
+               char decode[DECODE_STR_LEN_MAX];

                kvm->events_ops->decode_key(kvm, &event->key, decode);
                if (strcmp(decode, "HLT")) {
-                       pr_info("%" PRIu64 " VM %d, vcpu %d: %s event took %" PRIu64 
"usec\n",
+                       pr_info("%" PRIu64 " VM %d, vcpu %d: %*s event took %" PRIu64 
"usec\n",
                                 sample->time, sample->pid, 
vcpu_record->vcpu_id,
-                                decode, time_diff/1000);
+                                32, decode, time_diff/1000);

This pr_info does not need the length.

David
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