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 <hem...@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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