Received-SPF: pass (google.com: domain of linux-kernel+bounces-15747-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Wed, 3 Jan 2024 13:27:15 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>, Song Liu <song@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>, Song Liu <song@kernel.org>,
	Ming Wang <wangming01@loongson.cn>,
	Ravi Bangoria <ravi.bangoria@amd.com>,
	Huacai Chen <chenhuacai@kernel.org>,
	Kan Liang <kan.liang@linux.intel.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	bpf@vger.kernel.org
Subject: Re: [PATCH v1] perf env: Avoid recursively taking env->bpf_progs.lock
Message-ID: <ZZWK43OPvGcd-BAR@kernel.org>
References: <20231207014655.1252484-1-irogers@google.com>
 <CAP-5=fWdAouBb7us44HOdd+ZfBj5fLFTuLCokbG8w3jVuQgTxw@mail.gmail.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CAP-5=fWdAouBb7us44HOdd+ZfBj5fLFTuLCokbG8w3jVuQgTxw@mail.gmail.com>

Em Tue, Jan 02, 2024 at 07:00:53PM -0800, Ian Rogers escreveu:
> On Wed, Dec 6, 2023 at 5:46 PM Ian Rogers <irogers@google.com> wrote:
> >
> > Add variants of perf_env__insert_bpf_prog_info, perf_env__insert_btf
> > and perf_env__find_btf prefixed with __ to indicate the
> > env->bpf_progs.lock is assumed held. Call these variants when the lock
> > is held to avoid recursively taking it and potentially having a thread
> > deadlock with itself.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> 
> Ping.

Applied, with that minor patch reduction hunk and this:

Fixes: f8dfeae009effc0b ("perf bpf: Show more BPF program info in print_bpf_prog_info()")

Song, can I have your Acked-by?

- Arnaldo

> 
> > ---
> > Previously this patch was part of a larger set:
> > https://lore.kernel.org/lkml/20231127220902.1315692-51-irogers@google.com/
> > ---
> >  tools/perf/util/bpf-event.c |  8 +++---
> >  tools/perf/util/bpf-event.h | 12 ++++-----
> >  tools/perf/util/env.c       | 53 +++++++++++++++++++++++--------------
> >  tools/perf/util/env.h       |  4 +++
> >  tools/perf/util/header.c    |  8 +++---
> >  5 files changed, 51 insertions(+), 34 deletions(-)
> >
> > diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
> > index 830711cae30d..3573e0b7ef3e 100644
> > --- a/tools/perf/util/bpf-event.c
> > +++ b/tools/perf/util/bpf-event.c
> > @@ -545,9 +545,9 @@ int evlist__add_bpf_sb_event(struct evlist *evlist, struct perf_env *env)
> >         return evlist__add_sb_event(evlist, &attr, bpf_event__sb_cb, env);
> >  }
> >
> > -void bpf_event__print_bpf_prog_info(struct bpf_prog_info *info,
> > -                                   struct perf_env *env,
> > -                                   FILE *fp)
> > +void __bpf_event__print_bpf_prog_info(struct bpf_prog_info *info,
> > +                                     struct perf_env *env,
> > +                                     FILE *fp)
> >  {
> >         __u32 *prog_lens = (__u32 *)(uintptr_t)(info->jited_func_lens);
> >         __u64 *prog_addrs = (__u64 *)(uintptr_t)(info->jited_ksyms);
> > @@ -563,7 +563,7 @@ void bpf_event__print_bpf_prog_info(struct bpf_prog_info *info,
> >         if (info->btf_id) {
> >                 struct btf_node *node;
> >
> > -               node = perf_env__find_btf(env, info->btf_id);
> > +               node = __perf_env__find_btf(env, info->btf_id);
> >                 if (node)
> >                         btf = btf__new((__u8 *)(node->data),
> >                                        node->data_size);
> > diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
> > index 1bcbd4fb6c66..e2f0420905f5 100644
> > --- a/tools/perf/util/bpf-event.h
> > +++ b/tools/perf/util/bpf-event.h
> > @@ -33,9 +33,9 @@ struct btf_node {
> >  int machine__process_bpf(struct machine *machine, union perf_event *event,
> >                          struct perf_sample *sample);
> >  int evlist__add_bpf_sb_event(struct evlist *evlist, struct perf_env *env);
> > -void bpf_event__print_bpf_prog_info(struct bpf_prog_info *info,
> > -                                   struct perf_env *env,
> > -                                   FILE *fp);
> > +void __bpf_event__print_bpf_prog_info(struct bpf_prog_info *info,
> > +                                     struct perf_env *env,
> > +                                     FILE *fp);
> >  #else
> >  static inline int machine__process_bpf(struct machine *machine __maybe_unused,
> >                                        union perf_event *event __maybe_unused,
> > @@ -50,9 +50,9 @@ static inline int evlist__add_bpf_sb_event(struct evlist *evlist __maybe_unused,
> >         return 0;
> >  }
> >
> > -static inline void bpf_event__print_bpf_prog_info(struct bpf_prog_info *info __maybe_unused,
> > -                                                 struct perf_env *env __maybe_unused,
> > -                                                 FILE *fp __maybe_unused)
> > +static inline void __bpf_event__print_bpf_prog_info(struct bpf_prog_info *info __maybe_unused,
> > +                                                   struct perf_env *env __maybe_unused,
> > +                                                   FILE *fp __maybe_unused)
> >  {
> >
> >  }
> > diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
> > index c68b7a004f29..cfdacbf29456 100644
> > --- a/tools/perf/util/env.c
> > +++ b/tools/perf/util/env.c
> > @@ -22,15 +22,20 @@ struct perf_env perf_env;
> >  #include "bpf-utils.h"
> >  #include <bpf/libbpf.h>
> >
> > -void perf_env__insert_bpf_prog_info(struct perf_env *env,
> > -                                   struct bpf_prog_info_node *info_node)
> > +void perf_env__insert_bpf_prog_info(struct perf_env *env, struct bpf_prog_info_node *info_node)
> > +{
> > +       down_write(&env->bpf_progs.lock);
> > +       __perf_env__insert_bpf_prog_info(env, info_node);
> > +       up_write(&env->bpf_progs.lock);
> > +}
> > +
> > +void __perf_env__insert_bpf_prog_info(struct perf_env *env, struct bpf_prog_info_node *info_node)
> >  {
> >         __u32 prog_id = info_node->info_linear->info.id;
> >         struct bpf_prog_info_node *node;
> >         struct rb_node *parent = NULL;
> >         struct rb_node **p;
> >
> > -       down_write(&env->bpf_progs.lock);
> >         p = &env->bpf_progs.infos.rb_node;
> >
> >         while (*p != NULL) {
> > @@ -42,15 +47,13 @@ void perf_env__insert_bpf_prog_info(struct perf_env *env,
> >                         p = &(*p)->rb_right;
> >                 } else {
> >                         pr_debug("duplicated bpf prog info %u\n", prog_id);
> > -                       goto out;
> > +                       return;
> >                 }
> >         }
> >
> >         rb_link_node(&info_node->rb_node, parent, p);
> >         rb_insert_color(&info_node->rb_node, &env->bpf_progs.infos);
> >         env->bpf_progs.infos_cnt++;
> > -out:
> > -       up_write(&env->bpf_progs.lock);
> >  }
> >
> >  struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
> > @@ -79,14 +82,22 @@ struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
> >  }
> >
> >  bool perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node)
> > +{
> > +       bool ret;
> > +
> > +       down_write(&env->bpf_progs.lock);
> > +       ret = __perf_env__insert_btf(env, btf_node);
> > +       up_write(&env->bpf_progs.lock);
> > +       return ret;
> > +}
> > +
> > +bool __perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node)
> >  {
> >         struct rb_node *parent = NULL;
> >         __u32 btf_id = btf_node->id;
> >         struct btf_node *node;
> >         struct rb_node **p;
> > -       bool ret = true;
> >
> > -       down_write(&env->bpf_progs.lock);
> >         p = &env->bpf_progs.btfs.rb_node;
> >
> >         while (*p != NULL) {
> > @@ -98,25 +109,31 @@ bool perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node)
> >                         p = &(*p)->rb_right;
> >                 } else {
> >                         pr_debug("duplicated btf %u\n", btf_id);
> > -                       ret = false;
> > -                       goto out;
> > +                       return false;
> >                 }
> >         }
> >
> >         rb_link_node(&btf_node->rb_node, parent, p);
> >         rb_insert_color(&btf_node->rb_node, &env->bpf_progs.btfs);
> >         env->bpf_progs.btfs_cnt++;
> > -out:
> > -       up_write(&env->bpf_progs.lock);
> > -       return ret;
> > +       return true;
> >  }
> >
> >  struct btf_node *perf_env__find_btf(struct perf_env *env, __u32 btf_id)
> > +{
> > +       struct btf_node *res;
> > +
> > +       down_read(&env->bpf_progs.lock);
> > +       res = __perf_env__find_btf(env, btf_id);
> > +       up_read(&env->bpf_progs.lock);
> > +       return res;
> > +}
> > +
> > +struct btf_node *__perf_env__find_btf(struct perf_env *env, __u32 btf_id)
> >  {
> >         struct btf_node *node = NULL;
> >         struct rb_node *n;
> >
> > -       down_read(&env->bpf_progs.lock);
> >         n = env->bpf_progs.btfs.rb_node;
> >
> >         while (n) {
> > @@ -126,13 +143,9 @@ struct btf_node *perf_env__find_btf(struct perf_env *env, __u32 btf_id)
> >                 else if (btf_id > node->id)
> >                         n = n->rb_right;
> >                 else
> > -                       goto out;
> > +                       return node;
> >         }
> > -       node = NULL;
> > -
> > -out:
> > -       up_read(&env->bpf_progs.lock);
> > -       return node;
> > +       return NULL;
> >  }
> >
> >  /* purge data in bpf_progs.infos tree */
> > diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
> > index bf7e3c4c211f..7c527e65c186 100644
> > --- a/tools/perf/util/env.h
> > +++ b/tools/perf/util/env.h
> > @@ -175,12 +175,16 @@ const char *perf_env__raw_arch(struct perf_env *env);
> >  int perf_env__nr_cpus_avail(struct perf_env *env);
> >
> >  void perf_env__init(struct perf_env *env);
> > +void __perf_env__insert_bpf_prog_info(struct perf_env *env,
> > +                                     struct bpf_prog_info_node *info_node);
> >  void perf_env__insert_bpf_prog_info(struct perf_env *env,
> >                                     struct bpf_prog_info_node *info_node);
> >  struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
> >                                                         __u32 prog_id);
> >  bool perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node);
> > +bool __perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node);
> >  struct btf_node *perf_env__find_btf(struct perf_env *env, __u32 btf_id);
> > +struct btf_node *__perf_env__find_btf(struct perf_env *env, __u32 btf_id);
> >
> >  int perf_env__numa_node(struct perf_env *env, struct perf_cpu cpu);
> >  char *perf_env__find_pmu_cap(struct perf_env *env, const char *pmu_name,
> > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> > index 08cc2febabde..02bf9d8b5f74 100644
> > --- a/tools/perf/util/header.c
> > +++ b/tools/perf/util/header.c
> > @@ -1849,8 +1849,8 @@ static void print_bpf_prog_info(struct feat_fd *ff, FILE *fp)
> >                 node = rb_entry(next, struct bpf_prog_info_node, rb_node);
> >                 next = rb_next(&node->rb_node);
> >
> > -               bpf_event__print_bpf_prog_info(&node->info_linear->info,
> > -                                              env, fp);
> > +               __bpf_event__print_bpf_prog_info(&node->info_linear->info,
> > +                                                env, fp);
> >         }
> >
> >         up_read(&env->bpf_progs.lock);
> > @@ -3188,7 +3188,7 @@ static int process_bpf_prog_info(struct feat_fd *ff, void *data __maybe_unused)
> >                 /* after reading from file, translate offset to address */
> >                 bpil_offs_to_addr(info_linear);
> >                 info_node->info_linear = info_linear;
> > -               perf_env__insert_bpf_prog_info(env, info_node);
> > +               __perf_env__insert_bpf_prog_info(env, info_node);
> >         }
> >
> >         up_write(&env->bpf_progs.lock);
> > @@ -3235,7 +3235,7 @@ static int process_bpf_btf(struct feat_fd *ff, void *data __maybe_unused)
> >                 if (__do_read(ff, node->data, data_size))
> >                         goto out;
> >
> > -               perf_env__insert_btf(env, node);
> > +               __perf_env__insert_btf(env, node);
> >                 node = NULL;
> >         }
> >
> > --
> > 2.43.0.rc2.451.g8631bc7472-goog
> >
> 

-- 

- Arnaldo