perf evsel: Fix use of inherit

perf stat doesn't mmap and its perfectly fine for it to use task-bound
counters with inheritance.

So set the attr.inherit on the caller and leave the syscall itself to
validate it.

When the mmap fails perf_evlist__mmap will just emit a warning if this
is the failure reason.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Link: http://lkml.kernel.org/r/20110414170121.GC3229@ghostprotocols.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index d852cefa20de..45da8d186b49 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -12,6 +12,7 @@
 #include "evlist.h"
 #include "evsel.h"
 #include "util.h"
+#include "debug.h"
 
 #include <sys/mman.h>
 
@@ -250,15 +251,19 @@ int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
         return evlist->mmap != NULL ? 0 : -ENOMEM;
 }
 
-static int __perf_evlist__mmap(struct perf_evlist *evlist, int cpu, int prot,
-                               int mask, int fd)
+static int __perf_evlist__mmap(struct perf_evlist *evlist, struct perf_evsel *evsel,
+                               int cpu, int prot, int mask, int fd)
 {
         evlist->mmap[cpu].prev = 0;
         evlist->mmap[cpu].mask = mask;
         evlist->mmap[cpu].base = mmap(NULL, evlist->mmap_len, prot,
                                       MAP_SHARED, fd, 0);
-        if (evlist->mmap[cpu].base == MAP_FAILED)
+        if (evlist->mmap[cpu].base == MAP_FAILED) {
+                if (evlist->cpus->map[cpu] == -1 && evsel->attr.inherit)
+                        ui__warning("Inherit is not allowed on per-task "
+                                    "events using mmap.\n");
                 return -1;
+        }
 
         perf_evlist__add_pollfd(evlist, fd);
         return 0;
@@ -312,7 +317,8 @@ int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite)
                                         if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT,
                                                   FD(first_evsel, cpu, 0)) != 0)
                                                 goto out_unmap;
-                                } else if (__perf_evlist__mmap(evlist, cpu, prot, mask, fd) < 0)
+                                } else if (__perf_evlist__mmap(evlist, evsel, cpu,
+                                                               prot, mask, fd) < 0)
                                         goto out_unmap;
 
                                 if ((evsel->attr.read_format & PERF_FORMAT_ID) &&