Re: [PATCH v6 6/7] perf dso: Reference counting related fixes
From: Arnaldo Carvalho de Melo
Date: Mon May 06 2024 - 10:44:29 EST
On Sat, May 04, 2024 at 02:38:02PM -0700, Ian Rogers wrote:
> Ensure gets and puts are better aligned fixing reference couting
> checking problems.
>
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> ---
> tools/perf/util/machine.c | 4 +--
> tools/perf/util/map.c | 1 +
> tools/perf/util/symbol-elf.c | 51 ++++++++++++++++++------------------
> 3 files changed, 28 insertions(+), 28 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 0b8fb14f5ff6..4a4541a2e887 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -683,7 +683,7 @@ static int machine__process_ksymbol_register(struct machine *machine,
> struct perf_sample *sample __maybe_unused)
> {
> struct symbol *sym;
> - struct dso *dso;
> + struct dso *dso = NULL;
> struct map *map = maps__find(machine__kernel_maps(machine), event->ksymbol.addr);
> int err = 0;
>
> @@ -696,7 +696,6 @@ static int machine__process_ksymbol_register(struct machine *machine,
> }
> dso__set_kernel(dso, DSO_SPACE__KERNEL);
> map = map__new2(0, dso);
> - dso__put(dso);
> if (!map) {
> err = -ENOMEM;
> goto out;
> @@ -735,6 +734,7 @@ static int machine__process_ksymbol_register(struct machine *machine,
> dso__insert_symbol(dso, sym);
> out:
> map__put(map);
> + dso__put(dso);
> return err;
> }
This seems to match the patch description, good, just aligning the puts
> diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> index 117c4bb78b35..e1d14936a60d 100644
> --- a/tools/perf/util/map.c
> +++ b/tools/perf/util/map.c
> @@ -200,6 +200,7 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
> dso__set_build_id(dso, dso__bid(header_bid_dso));
> dso__set_header_build_id(dso, 1);
> }
> + dso__put(header_bid_dso);
> }
> dso__put(dso);
> }
But this is a missing one, so not aligning, but fixing a separate issue,
i.e. a missing put? Should go on a different patch, probably with a
Fixes.
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index 3be5e8d1e278..e398abfd13a0 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -1419,7 +1419,7 @@ void __weak arch__sym_update(struct symbol *s __maybe_unused,
> static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
> GElf_Sym *sym, GElf_Shdr *shdr,
> struct maps *kmaps, struct kmap *kmap,
> - struct dso **curr_dsop, struct map **curr_mapp,
> + struct dso **curr_dsop,
This one removes an argument, so look like a separate patch as well,
needs a description of why removing the argument is the right thing to
do here.
> const char *section_name,
> bool adjust_kernel_syms, bool kmodule, bool *remap_kernel,
> u64 max_text_sh_offset)
> @@ -1470,8 +1470,8 @@ static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
> map__set_pgoff(map, shdr->sh_offset);
> }
>
> - *curr_mapp = map;
> - *curr_dsop = dso;
> + dso__put(*curr_dsop);
> + *curr_dsop = dso__get(dso);
> return 0;
> }
>
> @@ -1484,8 +1484,8 @@ static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
> */
> if (kmodule && adjust_kernel_syms && is_exe_text(shdr->sh_flags) &&
> shdr->sh_offset <= max_text_sh_offset) {
> - *curr_mapp = map;
> - *curr_dsop = dso;
> + dso__put(*curr_dsop);
> + *curr_dsop = dso__get(dso);
> return 0;
> }
>
> @@ -1507,10 +1507,10 @@ static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
> dso__set_binary_type(curr_dso, dso__binary_type(dso));
> dso__set_adjust_symbols(curr_dso, dso__adjust_symbols(dso));
> curr_map = map__new2(start, curr_dso);
> - dso__put(curr_dso);
> - if (curr_map == NULL)
> + if (curr_map == NULL) {
> + dso__put(curr_dso);
> return -1;
> -
> + }
> if (dso__kernel(curr_dso))
> map__kmap(curr_map)->kmaps = kmaps;
>
> @@ -1524,21 +1524,15 @@ static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
> dso__set_symtab_type(curr_dso, dso__symtab_type(dso));
> if (maps__insert(kmaps, curr_map))
> return -1;
> - /*
> - * Add it before we drop the reference to curr_map, i.e. while
> - * we still are sure to have a reference to this DSO via
> - * *curr_map->dso.
> - */
> dsos__add(&maps__machine(kmaps)->dsos, curr_dso);
> - /* kmaps already got it */
> - map__put(curr_map);
> dso__set_loaded(curr_dso);
> - *curr_mapp = curr_map;
> + dso__put(*curr_dsop);
> *curr_dsop = curr_dso;
> } else {
> - *curr_dsop = map__dso(curr_map);
> - map__put(curr_map);
> + dso__put(*curr_dsop);
> + *curr_dsop = dso__get(map__dso(curr_map));
> }
> + map__put(curr_map);
>
> return 0;
> }
> @@ -1549,11 +1543,9 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
> {
> struct kmap *kmap = dso__kernel(dso) ? map__kmap(map) : NULL;
> struct maps *kmaps = kmap ? map__kmaps(map) : NULL;
> - struct map *curr_map = map;
> - struct dso *curr_dso = dso;
> + struct dso *curr_dso = NULL;
> Elf_Data *symstrs, *secstrs, *secstrs_run, *secstrs_sym;
> uint32_t nr_syms;
> - int err = -1;
> uint32_t idx;
> GElf_Ehdr ehdr;
> GElf_Shdr shdr;
> @@ -1656,6 +1648,7 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
> if (kmodule && adjust_kernel_syms)
> max_text_sh_offset = max_text_section(runtime_ss->elf, &runtime_ss->ehdr);
>
> + curr_dso = dso__get(dso);
> elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
> struct symbol *f;
> const char *elf_name = elf_sym__name(&sym, symstrs);
> @@ -1744,9 +1737,13 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
> --sym.st_value;
>
> if (dso__kernel(dso)) {
> - if (dso__process_kernel_symbol(dso, map, &sym, &shdr, kmaps, kmap, &curr_dso, &curr_map,
> - section_name, adjust_kernel_syms, kmodule,
> - &remap_kernel, max_text_sh_offset))
> + if (dso__process_kernel_symbol(dso, map, &sym, &shdr,
> + kmaps, kmap, &curr_dso,
> + section_name,
> + adjust_kernel_syms,
> + kmodule,
> + &remap_kernel,
> + max_text_sh_offset))
Can you please avoid reflowing to reduce the cost of reviewing? If this
was just:
- if (dso__process_kernel_symbol(dso, map, &sym, &shdr, kmaps, kmap, &curr_dso, &curr_map,
section_name, adjust_kernel_syms, kmodule,
&remap_kernel, max_text_sh_offset))
+ if (dso__process_kernel_symbol(dso, map, &sym, &shdr, kmaps, kmap, &curr_dso,
section_name, adjust_kernel_syms, kmodule,
&remap_kernel, max_text_sh_offset))
The actual change would be quickly spotted as just the line where it
takes place gets changed.
I applied all the patches in this series but this one, please split it
as described.
The tests I run after each patch before this one passed, thanks for
addressing the issues I reported,
I'm pushing what I have to tmp.perf-tools-next,
- Arnaldo
> goto out_elf_end;
> } else if ((used_opd && runtime_ss->adjust_symbols) ||
> (!used_opd && syms_ss->adjust_symbols)) {
> @@ -1795,6 +1792,7 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
> __symbols__insert(dso__symbols(curr_dso), f, dso__kernel(dso));
> nr++;
> }
> + dso__put(curr_dso);
>
> /*
> * For misannotated, zeroed, ASM function sizes.
> @@ -1810,9 +1808,10 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
> maps__fixup_end(kmaps);
> }
> }
> - err = nr;
> + return nr;
> out_elf_end:
> - return err;
> + dso__put(curr_dso);
> + return -1;
> }
>
> int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss,
> --
> 2.45.0.rc1.225.g2a3ae87e7f-goog
>