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    Subject[PATCH v2 4/5] perf/sdt: Delete SDT events from cache
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    This patch adds the support to delete SDT events from the cache.
    To delete an event corresponding to a file, first the cache is read into
    the file_hash list. The key is calculated from the file name.
    And then, the file_list for that file_hash entry is traversed to find out
    the target file_list entry. Once, it is found, its contents are all freed up.

    # ./perf sdt-cache --del /usr/lib64/libc-2.16.so

    8 events removed for /usr/lib64/libc-2.16.so!

    Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
    ---
    tools/perf/builtin-sdt-cache.c | 28 +++++++++++++++++++++++++++-
    tools/perf/util/parse-events.h | 1 +
    tools/perf/util/sdt.c | 35 +++++++++++++++++++++++++++++++++++
    3 files changed, 63 insertions(+), 1 deletion(-)

    diff --git a/tools/perf/builtin-sdt-cache.c b/tools/perf/builtin-sdt-cache.c
    index 5faf8e5..12276da 100644
    --- a/tools/perf/builtin-sdt-cache.c
    +++ b/tools/perf/builtin-sdt-cache.c
    @@ -16,6 +16,7 @@
    /* Session management structure */
    static struct {
    bool add;
    + bool del;
    bool dump;
    const char *target;
    } params;
    @@ -29,6 +30,15 @@ static int opt_add_sdt_events(const struct option *opt __maybe_unused,
    return 0;
    }

    +static int opt_del_sdt_events(const struct option *opt __maybe_unused,
    + const char *str, int unset __maybe_unused)
    +{
    + params.del = true;
    + params.target = str;
    +
    + return 0;
    +}
    +
    static int opt_show_sdt_events(const struct option *opt __maybe_unused,
    const char *str, int unset __maybe_unused)
    {
    @@ -45,13 +55,17 @@ int cmd_sdt_cache(int argc, const char **argv, const char *prefix __maybe_unused
    OPT_CALLBACK('a', "add", NULL, "filename",
    "add SDT events from a file.",
    opt_add_sdt_events),
    + OPT_CALLBACK('d', "del", NULL, "filename",
    + "Remove SDT events corresponding to a file from the"
    + " sdt cache.",
    + opt_del_sdt_events),
    OPT_CALLBACK_NOOPT('s', "dump", NULL, "show SDT events",
    "Read SDT events from cache and display.",
    opt_show_sdt_events),
    OPT_END()
    };
    const char * const sdt_cache_usage[] = {
    - "perf sdt_cache [--add filename | --dump]",
    + "perf sdt_cache [--add filename | --del filename | --dump]",
    NULL
    };

    @@ -63,6 +77,10 @@ int cmd_sdt_cache(int argc, const char **argv, const char *prefix __maybe_unused

    symbol__elf_init();
    if (params.add) {
    + if (params.del) {
    + pr_err("Error: Don't use --del with --add\n");
    + usage_with_options(sdt_cache_usage, sdt_cache_options);
    + }
    if (params.dump) {
    pr_err("Error: Don't use --dump with --add\n");
    usage_with_options(sdt_cache_usage, sdt_cache_options);
    @@ -70,6 +88,14 @@ int cmd_sdt_cache(int argc, const char **argv, const char *prefix __maybe_unused
    ret = add_sdt_events(params.target);
    if (ret < 0)
    pr_err("Cannot add SDT events to cache!\n");
    + } else if (params.del) {
    + if (params.dump) {
    + pr_err("Error: Don't use --dump with --del\n");
    + usage_with_options(sdt_cache_usage, sdt_cache_options);
    + }
    + ret = remove_sdt_events(params.target);
    + if (ret < 0)
    + pr_err("Cannot remove SDT events from cache!\n");
    } else if (params.dump) {
    if (argc == 0) {
    ret = dump_sdt_events();
    diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
    index f43e6aa..2297af7 100644
    --- a/tools/perf/util/parse-events.h
    +++ b/tools/perf/util/parse-events.h
    @@ -111,5 +111,6 @@ extern int valid_debugfs_mount(const char *debugfs);

    int add_sdt_events(const char *file);
    int dump_sdt_events(void);
    +int remove_sdt_events(const char *str);

    #endif /* __PERF_PARSE_EVENTS_H */
    diff --git a/tools/perf/util/sdt.c b/tools/perf/util/sdt.c
    index f2c7dc0..e8eea48 100644
    --- a/tools/perf/util/sdt.c
    +++ b/tools/perf/util/sdt.c
    @@ -711,3 +711,38 @@ int dump_sdt_events(void)
    file_hash_list__display(&file_hash);
    return 0;
    }
    +
    +/**
    + * remove_sdt_events: remove SDT events from cache
    + * @str: filename
    + *
    + * Removes the SDT events from the cache corresponding to the file name
    + * @str.
    + */
    +int remove_sdt_events(const char *str)
    +{
    + struct hash_list file_hash;
    + char *res_path;
    + int nr_del;
    +
    + /* Initialize the hash_lists */
    + file_hash_list__init(&file_hash);
    + res_path = realpath(str, NULL);
    + if (!res_path)
    + return -ENOMEM;
    +
    + /* Remove the file_list entry from file_hash and update the event_hash */
    + nr_del = file_hash_list__remove(&file_hash, res_path);
    + if (nr_del > 0) {
    + printf("%d events removed for %s!\n", nr_del, res_path);
    + flush_hash_list_to_cache(&file_hash);
    + goto out;
    + } else if (!nr_del) {
    + pr_err("Events for %s not found!\n", str);
    + }
    +
    +out:
    + free(res_path);
    + file_hash_list__cleanup(&file_hash);
    + return nr_del;
    +}


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