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    Subject[PATCH 12/25] perf tools: Add dso__data_get/put_fd()
    Date
    From: Namhyung Kim <namhyung@kernel.org>

    Using dso__data_fd() in multi-thread environment is not safe since
    returned fd can be closed and/or reused anytime.

    So convert it to the dso__data_get/put_fd() pair to protect the access
    with lock.

    The original dso__data_fd() is deprecated and kept only for testing.

    Signed-off-by: Namhyung Kim <namhyung@kernel.org>
    Acked-by: Adrian Hunter <adrian.hunter@intel.com>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/1432137821-10853-3-git-send-email-namhyung@kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/tests/dso-data.c | 11 +++++++++++
    tools/perf/util/dso.c | 31 ++++++++++++++++++++++---------
    tools/perf/util/dso.h | 13 +++++++++----
    tools/perf/util/unwind-libunwind.c | 11 ++++++++---
    4 files changed, 50 insertions(+), 16 deletions(-)

    diff --git a/tools/perf/tests/dso-data.c b/tools/perf/tests/dso-data.c
    index 513e5febbe5a..3e41c61bd861 100644
    --- a/tools/perf/tests/dso-data.c
    +++ b/tools/perf/tests/dso-data.c
    @@ -99,6 +99,17 @@ struct test_data_offset offsets[] = {
    },
    };

    +/* move it from util/dso.c for compatibility */
    +static int dso__data_fd(struct dso *dso, struct machine *machine)
    +{
    + int fd = dso__data_get_fd(dso, machine);
    +
    + if (fd >= 0)
    + dso__data_put_fd(dso);
    +
    + return fd;
    +}
    +
    int test__dso_data(void)
    {
    struct machine machine;
    diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
    index e95e850dd832..7e11a700303f 100644
    --- a/tools/perf/util/dso.c
    +++ b/tools/perf/util/dso.c
    @@ -473,25 +473,35 @@ out:
    }

    /**
    - * dso__data_fd - Get dso's data file descriptor
    + * dso__data_get_fd - Get dso's data file descriptor
    * @dso: dso object
    * @machine: machine object
    *
    * External interface to find dso's file, open it and
    - * returns file descriptor.
    + * returns file descriptor. It should be paired with
    + * dso__data_put_fd() if it returns non-negative value.
    */
    -int dso__data_fd(struct dso *dso, struct machine *machine)
    +int dso__data_get_fd(struct dso *dso, struct machine *machine)
    {
    if (dso->data.status == DSO_DATA_STATUS_ERROR)
    return -1;

    - pthread_mutex_lock(&dso__data_open_lock);
    + if (pthread_mutex_lock(&dso__data_open_lock) < 0)
    + return -1;
    +
    try_to_open_dso(dso, machine);
    - pthread_mutex_unlock(&dso__data_open_lock);
    +
    + if (dso->data.fd < 0)
    + pthread_mutex_unlock(&dso__data_open_lock);

    return dso->data.fd;
    }

    +void dso__data_put_fd(struct dso *dso __maybe_unused)
    +{
    + pthread_mutex_unlock(&dso__data_open_lock);
    +}
    +
    bool dso__data_status_seen(struct dso *dso, enum dso_data_status_seen by)
    {
    u32 flag = 1 << by;
    @@ -1199,12 +1209,15 @@ size_t dso__fprintf(struct dso *dso, enum map_type type, FILE *fp)
    enum dso_type dso__type(struct dso *dso, struct machine *machine)
    {
    int fd;
    + enum dso_type type = DSO__TYPE_UNKNOWN;

    - fd = dso__data_fd(dso, machine);
    - if (fd < 0)
    - return DSO__TYPE_UNKNOWN;
    + fd = dso__data_get_fd(dso, machine);
    + if (fd >= 0) {
    + type = dso__type_fd(fd);
    + dso__data_put_fd(dso);
    + }

    - return dso__type_fd(fd);
    + return type;
    }

    int dso__strerror_load(struct dso *dso, char *buf, size_t buflen)
    diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
    index b26ec3ab1336..bcec06ad73a2 100644
    --- a/tools/perf/util/dso.h
    +++ b/tools/perf/util/dso.h
    @@ -240,7 +240,8 @@ int __kmod_path__parse(struct kmod_path *m, const char *path,

    /*
    * The dso__data_* external interface provides following functions:
    - * dso__data_fd
    + * dso__data_get_fd
    + * dso__data_put_fd
    * dso__data_close
    * dso__data_size
    * dso__data_read_offset
    @@ -257,8 +258,11 @@ int __kmod_path__parse(struct kmod_path *m, const char *path,
    * The current usage of the dso__data_* interface is as follows:
    *
    * Get DSO's fd:
    - * int fd = dso__data_fd(dso, machine);
    - * USE 'fd' SOMEHOW
    + * int fd = dso__data_get_fd(dso, machine);
    + * if (fd >= 0) {
    + * USE 'fd' SOMEHOW
    + * dso__data_put_fd(dso);
    + * }
    *
    * Read DSO's data:
    * n = dso__data_read_offset(dso_0, &machine, 0, buf, BUFSIZE);
    @@ -277,7 +281,8 @@ int __kmod_path__parse(struct kmod_path *m, const char *path,
    *
    * TODO
    */
    -int dso__data_fd(struct dso *dso, struct machine *machine);
    +int dso__data_get_fd(struct dso *dso, struct machine *machine);
    +void dso__data_put_fd(struct dso *dso __maybe_unused);
    void dso__data_close(struct dso *dso);

    off_t dso__data_size(struct dso *dso, struct machine *machine);
    diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
    index 7b09a443a280..f079b63f0b7f 100644
    --- a/tools/perf/util/unwind-libunwind.c
    +++ b/tools/perf/util/unwind-libunwind.c
    @@ -269,13 +269,14 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
    u64 offset = dso->data.eh_frame_hdr_offset;

    if (offset == 0) {
    - fd = dso__data_fd(dso, machine);
    + fd = dso__data_get_fd(dso, machine);
    if (fd < 0)
    return -EINVAL;

    /* Check the .eh_frame section for unwinding info */
    offset = elf_section_offset(fd, ".eh_frame_hdr");
    dso->data.eh_frame_hdr_offset = offset;
    + dso__data_put_fd(dso);
    }

    if (offset)
    @@ -294,13 +295,14 @@ static int read_unwind_spec_debug_frame(struct dso *dso,
    u64 ofs = dso->data.debug_frame_offset;

    if (ofs == 0) {
    - fd = dso__data_fd(dso, machine);
    + fd = dso__data_get_fd(dso, machine);
    if (fd < 0)
    return -EINVAL;

    /* Check the .debug_frame section for unwinding info */
    ofs = elf_section_offset(fd, ".debug_frame");
    dso->data.debug_frame_offset = ofs;
    + dso__data_put_fd(dso);
    }

    *offset = ofs;
    @@ -353,10 +355,13 @@ find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
    #ifndef NO_LIBUNWIND_DEBUG_FRAME
    /* Check the .debug_frame section for unwinding info */
    if (!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
    - int fd = dso__data_fd(map->dso, ui->machine);
    + int fd = dso__data_get_fd(map->dso, ui->machine);
    int is_exec = elf_is_exec(fd, map->dso->name);
    unw_word_t base = is_exec ? 0 : map->start;

    + if (fd >= 0)
    + dso__data_put_fd(dso);
    +
    memset(&di, 0, sizeof(di));
    if (dwarf_find_debug_frame(0, &di, ip, base, map->dso->name,
    map->start, map->end))
    --
    2.1.0


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