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perf kvm: Fix segfault with report and mixed guestmount use

Using the guestmount option on record:
    $ perf kvm --guest --host --guestmount=/tmp/guest-mount record -ag

But not the subsequent report:
    $ perf kvm report

causes a SEGFAULT in the usual place:
(gdb) bt
0  0x0000000000470356 in machine__mmap_name (self=0x0, bf=0x7fffffffbdb0 " z\370\367\377\177", size=
    4096) at util/map.c:712
1  0x00000000004453e8 in perf_event__process_kernel_mmap (tool=0x7fffffffde10, event=0x7ffff7f87e38,
    machine=0x0) at util/event.c:550
2  0x00000000004458c9 in perf_event__process_mmap (tool=0x7fffffffde10, event=0x7ffff7f87e38, sample=
    0x7fffffffd2a0, machine=0x0) at util/event.c:656
3  0x00000000004733e0 in perf_session_deliver_event (session=0x91aca0, event=0x7ffff7f87e38, sample=
    0x7fffffffd2a0, tool=0x7fffffffde10, file_offset=7736) at util/session.c:979
...

The MMAP events in this case already contain the full path to the
module. No need to require it for the report path to.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1341241977-71535-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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dsahern authored and Arnaldo Carvalho de Melo committed Jul 2, 2012
1 parent 207b579 commit 7ed97ad41ffa94040dfd593948962a7e9e7b0db9
Showing with 15 additions and 14 deletions.
  1. +15 −14 tools/perf/util/map.c
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@@ -669,25 +669,26 @@ struct machine *machines__find(struct rb_root *self, pid_t pid)
struct machine *machines__findnew(struct rb_root *self, pid_t pid)
{
char path[PATH_MAX];
- const char *root_dir;
+ const char *root_dir = "";
struct machine *machine = machines__find(self, pid);
- if (!machine || machine->pid != pid) {
- if (pid == HOST_KERNEL_ID || pid == DEFAULT_GUEST_KERNEL_ID)
- root_dir = "";
- else {
- if (!symbol_conf.guestmount)
- goto out;
- sprintf(path, "%s/%d", symbol_conf.guestmount, pid);
- if (access(path, R_OK)) {
- pr_err("Can't access file %s\n", path);
- goto out;
- }
- root_dir = path;
+ if (machine && (machine->pid == pid))
+ goto out;
+
+ if ((pid != HOST_KERNEL_ID) &&
+ (pid != DEFAULT_GUEST_KERNEL_ID) &&
+ (symbol_conf.guestmount)) {
+ sprintf(path, "%s/%d", symbol_conf.guestmount, pid);
+ if (access(path, R_OK)) {
+ pr_err("Can't access file %s\n", path);
+ machine = NULL;
+ goto out;
}
- machine = machines__add(self, pid, root_dir);
+ root_dir = path;
}
+ machine = machines__add(self, pid, root_dir);
+
out:
return machine;
}

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