Re: [PATCH perf/core 21/22] perf: Fix machine.vmlinux_maps to make sure to clear the old one

Arnaldo Carvalho de Melo
2015-12-09T15:23:13Z

Em Wed, Dec 09, 2015 at 11:11:33AM +0900, Masami Hiramatsu escreveu:
> Fix machine.vmlinux_maps to make sure to clear the old one
> if it is renewal. This can leak the previous maps on the
> vmlinux_maps because those are just overwritten.
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> ---
> tools/perf/util/machine.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index bfc289c..3172aa5 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -44,6 +44,8 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
> machine->comm_exec = false;
> machine->kernel_start = 0;
>
> + memset(machine->vmlinux_maps, 0, sizeof(struct map *) * MAP__NR_TYPES);

Simpler:

memset(machine->vmlinux_maps, 0, sizeof(machine->vmlinux_maps));

struct machine {
...
struct map *vmlinux_maps[MAP__NR_TYPES];
...
};

[acme@zoo c]$ cat pointer_array_sizeof.c
#include <stdio.h>

struct foo { int *array[2]; };
struct bar { int *array[4]; };

int main(void)
{
struct foo *foo; struct bar *bar;

printf("sizeof(foo->array)=%zd\n", sizeof(foo->array));
printf("sizeof(bar->array)=%zd\n", sizeof(bar->array));
return 0;
}
[acme@zoo c]$ make pointer_array_sizeof
cc pointer_array_sizeof.c -o pointer_array_sizeof
[acme@zoo c]$ ./pointer_array_sizeof
sizeof(foo->array)=16
sizeof(bar->array)=32
[acme@zoo c]$

> +
> machine->root_dir = strdup(root_dir);
> if (machine->root_dir == NULL)
> return -ENOMEM;
> @@ -770,6 +772,9 @@ int __machine__create_kernel_maps(struct machine *machine, struct dso *kernel)
> enum map_type type;
> u64 start = machine__get_running_kernel_start(machine, NULL);
>
> + /* In case of renewal the kernel map, destroy previous one */
> + machine__destroy_kernel_maps(machine);
> +
> for (type = 0; type < MAP__NR_TYPES; ++type) {
> struct kmap *kmap;
> struct map *map;