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 event(s) removed for /usr/lib64/libc-2.16.so

Signed-off-by: Hemant Kumar <hem...@linux.vnet.ibm.com>
---
 tools/perf/Documentation/perf-sdt-cache.txt |    6 +++-
 tools/perf/builtin-sdt-cache.c              |   21 +++++++++++++-
 tools/perf/util/parse-events.h              |    1 +
 tools/perf/util/sdt.c                       |   41 +++++++++++++++++++++++++++
 4 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Documentation/perf-sdt-cache.txt 
b/tools/perf/Documentation/perf-sdt-cache.txt
index e57a867..523dcda 100644
--- a/tools/perf/Documentation/perf-sdt-cache.txt
+++ b/tools/perf/Documentation/perf-sdt-cache.txt
@@ -8,7 +8,7 @@ perf-sdt-cache - Manage SDT events' cache.
 SYNOPSIS
 --------
 [verse]
-'perf sdt-cache --add <file_name>'
+'perf sdt-cache [--add | --del] <file_name>'
 'perf sdt-cache --dump'
 
 DESCRIPTION
@@ -23,6 +23,10 @@ OPTIONS
 --add::
         Add SDT events in the specified file to the cache. Takes file name
        as an argument.
+-d::
+--del::
+        Remove SDT events in the specified file from the cache. Takes file as 
an
+       argument.
 -D::
 --dump::
        Dump the contents of SDT events cache onto stdout.
diff --git a/tools/perf/builtin-sdt-cache.c b/tools/perf/builtin-sdt-cache.c
index 11f41a2..b35d844 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 +30,16 @@ 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)
 {
@@ -45,6 +56,9 @@ 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('D', "dump", NULL, "show SDT events",
                                   "Read SDT events from cache and display.",
                                   opt_show_sdt_events),
@@ -52,13 +66,14 @@ int cmd_sdt_cache(int argc, const char **argv, const char 
*prefix __maybe_unused
        };
 
        const char * const sdt_cache_usage[] = {
-               "perf sdt-cache --add filename",
+               "perf sdt-cache [--add | --del] filename",
                "perf sdt-cache --dump",
                NULL
        };
 
        set_option_flag(sdt_cache_options, 'a', "add", PARSE_OPT_EXCLUSIVE);
        set_option_flag(sdt_cache_options, 'D', "dump", PARSE_OPT_EXCLUSIVE);
+       set_option_flag(sdt_cache_options, 'd', "del", PARSE_OPT_EXCLUSIVE);
 
        argc = parse_options(argc, argv, sdt_cache_options,
                             sdt_cache_usage,
@@ -71,6 +86,10 @@ 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) {
+               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 cca6859..cafdab6 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -125,5 +125,6 @@ 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 5f70dd6..9dd7e4da 100644
--- a/tools/perf/util/sdt.c
+++ b/tools/perf/util/sdt.c
@@ -192,6 +192,7 @@ static int file_hash_list__remove(struct hash_table 
*file_hash,
                nr_del = cleanup_sdt_note_list(&fse->sdt_list);
                hlist_del(&fse->file_list);
                free(fse);
+               break;
        }
        free(res_path);
        return nr_del;
@@ -661,3 +662,43 @@ int dump_sdt_events(void)
        file_hash_list__cleanup(&file_hash);
        return ret;
 }
+
+/**
+ * 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_table file_hash;
+       char *res_path;
+       int nr_del, ret = -ENOMEM;
+
+       res_path = realpath(str, NULL);
+       if (!res_path) {
+               pr_err("%s: Bad file name\n", str);
+               goto out_err;
+       }
+       /* Initialize the hash_lists */
+       ret = file_hash_list__init(&file_hash);
+       if (ret < 0)
+               goto out;
+
+       /* Remove the file_list entry from file_hash and update the file_hash */
+       nr_del = file_hash_list__remove(&file_hash, res_path);
+       if (nr_del > 0) {
+               printf("%4d event(s) removed for %s\n", nr_del, res_path);
+               flush_hash_list_to_cache(&file_hash);
+               ret = nr_del;
+               goto out;
+       } else if (!nr_del)
+               pr_err("Error: Events for %s not found\n", str);
+
+out:
+       free(res_path);
+       file_hash_list__cleanup(&file_hash);
+out_err:
+       return ret;
+}

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