[tip:perf/core] perf symbols: Cleanup the code flow of dso__find_kallsyms

From: tip-bot for Masami Hiramatsu
Date: Thu Jun 02 2016 - 02:35:34 EST


Commit-ID: 4e4b6c0668dcd907a36d281802beafa96c916548
Gitweb: http://git.kernel.org/tip/4e4b6c0668dcd907a36d281802beafa96c916548
Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
AuthorDate: Sun, 29 May 2016 00:15:28 +0900
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 30 May 2016 13:15:02 -0300

perf symbols: Cleanup the code flow of dso__find_kallsyms

Cleanup the code flow of dso__find_kallsyms() to remove redundant
checking code and add some comment for readability.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Hemant Kumar <hemant@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20160528151522.16098.43446.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/symbol.c | 36 +++++++++++++-----------------------
1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index a469346..1df6092 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1674,21 +1674,8 @@ static char *dso__find_kallsyms(struct dso *dso, struct map *map)
sizeof(host_build_id)) == 0)
is_host = dso__build_id_equal(dso, host_build_id);

- build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
-
- scnprintf(path, sizeof(path), "%s/%s/%s", buildid_dir,
- DSO__NAME_KCORE, sbuild_id);
-
- /* Use /proc/kallsyms if possible */
+ /* Try a fast path for /proc/kallsyms if possible */
if (is_host) {
- DIR *d;
-
- /* If no cached kcore go with /proc/kallsyms */
- d = opendir(path);
- if (!d)
- goto proc_kallsyms;
- closedir(d);
-
/*
* Do not check the build-id cache, unless we know we cannot use
* /proc/kcore or module maps don't match to /proc/kallsyms.
@@ -1699,18 +1686,24 @@ static char *dso__find_kallsyms(struct dso *dso, struct map *map)
if (filename__readable("/proc/kcore") &&
!validate_kcore_addresses("/proc/kallsyms", map))
goto proc_kallsyms;
-
- /* Find kallsyms in build-id cache with kcore */
- if (!find_matching_kcore(map, path, sizeof(path)))
- return strdup(path);
-
- goto proc_kallsyms;
}

+ build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
+
/* Find kallsyms in build-id cache with kcore */
+ scnprintf(path, sizeof(path), "%s/%s/%s",
+ buildid_dir, DSO__NAME_KCORE, sbuild_id);
+
if (!find_matching_kcore(map, path, sizeof(path)))
return strdup(path);

+ /* Use current /proc/kallsyms if possible */
+ if (is_host) {
+proc_kallsyms:
+ return strdup("/proc/kallsyms");
+ }
+
+ /* Finally, find a cache of kallsyms */
scnprintf(path, sizeof(path), "%s/%s/%s",
buildid_dir, DSO__NAME_KALLSYMS, sbuild_id);

@@ -1721,9 +1714,6 @@ static char *dso__find_kallsyms(struct dso *dso, struct map *map)
}

return strdup(path);
-
-proc_kallsyms:
- return strdup("/proc/kallsyms");
}

static int dso__load_kernel_sym(struct dso *dso, struct map *map,