[PATCH v1 09/11] perf tools: Remove redundant chroot handling

[Namhyung Kim]

Now that nsinfo__mountns_enter() enters the target process's chroot
alongside its mount namespace, callers inside a mountns context no
longer need to manually prepend the target's root directory path via
dso__filename_with_chroot() or filename_with_chroot().

Remove dso__filename_with_chroot() and filename_with_chroot() and use
the DSO path directly within the mountns scope.

Assisted-by: LLM
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/util/dso.c    | 29 ++---------------------------
 tools/perf/util/dso.h    |  2 --
 tools/perf/util/symbol.c |  8 --------
 tools/perf/util/util.c   | 31 -------------------------------
 tools/perf/util/util.h   |  2 --
 5 files changed, 2 insertions(+), 70 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index ce98613868e7d371..4331b48505b2b10e 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -585,11 +585,6 @@ static int do_open(char *name) EXCLUSIVE_LOCKS_REQUIRED(_dso__data_open_lock)
 	return -1;
 }
 
-char *dso__filename_with_chroot(const struct dso *dso, const char *filename)
-{
-	return filename_with_chroot(nsinfo__pid(dso__nsinfo_const(dso)), filename);
-}
-
 char *dso__get_filename(struct dso *dso, const char *root_dir, bool *decomp,
 			enum dso_binary_type type)
 {
@@ -603,28 +598,8 @@ char *dso__get_filename(struct dso *dso, const char *root_dir, bool *decomp,
 	if (dso__read_binary_type_filename(dso, type, root_dir, name, PATH_MAX))
 		goto out;
 
-	if (!is_regular_file(name)) {
-		struct stat st;
-		char *new_name;
-
-		/*
-		 * errno only reflects the failure reason when stat() itself
-		 * failed: a successful stat() on a non-regular file (e.g. a
-		 * directory) leaves a stale errno, which a previous failed
-		 * iteration of the try_to_open_dso() fallback loop may have
-		 * set to ENOENT.
-		 */
-		if (stat(name, &st) == 0 || errno != ENOENT ||
-		    dso__nsinfo(dso) == NULL)
-			goto out;
-
-		new_name = dso__filename_with_chroot(dso, name);
-		if (!new_name)
-			goto out;
-
-		free(name);
-		name = new_name;
-	}
+	if (!is_regular_file(name))
+		goto out;
 
 	if (dso__needs_decompress(dso)) {
 		char newpath[KMOD_DECOMP_LEN];
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 3329f417810c25a4..e53c83c23c578918 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -826,8 +826,6 @@ static inline bool dso__has_symbols(const struct dso *dso)
 	return !RB_EMPTY_ROOT(&RC_CHK_ACCESS(dso)->symbols.rb_root);
 }
 
-char *dso__filename_with_chroot(const struct dso *dso, const char *filename);
-
 bool dso__sorted_by_name(const struct dso *dso);
 void dso__set_sorted_by_name(struct dso *dso);
 void dso__sort_by_name(struct dso *dso);
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b61a574ce9a30721..807e433c770812a4 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1902,14 +1902,6 @@ int dso__load(struct dso *dso, struct map *map)
 			nsinfo__mountns_exit(&nsc);
 
 		is_reg = is_regular_file(name);
-		if (!is_reg && errno == ENOENT && dso__nsinfo(dso)) {
-			char *new_name = dso__filename_with_chroot(dso, name);
-			if (new_name) {
-				is_reg = is_regular_file(new_name);
-				strlcpy(name, new_name, PATH_MAX);
-				free(new_name);
-			}
-		}
 
 #ifdef HAVE_LIBBFD_SUPPORT
 		if (is_reg)
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 8f7cd32f524dc10e..443b1d2b4748bfe4 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -451,37 +451,6 @@ void perf_debuginfod_setup(struct perf_debuginfod *di)
 #endif
 }
 
-/*
- * Return a new filename prepended with task's root directory if it's in
- * a chroot.  Callers should free the returned string.
- */
-char *filename_with_chroot(int pid, const char *filename)
-{
-	char buf[PATH_MAX];
-	char proc_root[32];
-	char *new_name = NULL;
-	int ret;
-
-	scnprintf(proc_root, sizeof(proc_root), "/proc/%d/root", pid);
-	ret = readlink(proc_root, buf, sizeof(buf) - 1);
-	if (ret <= 0)
-		return NULL;
-
-	/* readlink(2) does not append a null byte to buf */
-	buf[ret] = '\0';
-
-	if (!strcmp(buf, "/"))
-		return NULL;
-
-	if (strstr(buf, "(deleted)"))
-		return NULL;
-
-	if (asprintf(&new_name, "%s/%s", buf, filename) < 0)
-		return NULL;
-
-	return new_name;
-}
-
 /*
  * Reallocate an array *arr of size *arr_sz so that it is big enough to contain
  * x elements of size msz, initializing new entries to *init_val or zero if
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index f8f1ff603c728086..b9adb58df976f29e 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -84,8 +84,6 @@ void perf_debuginfod_setup(struct perf_debuginfod *di);
 
 const char *perf_basename(const char *path);
 
-char *filename_with_chroot(int pid, const char *filename);
-
 int do_realloc_array_as_needed(void **arr, size_t *arr_sz, size_t x,
 			       size_t msz, const void *init_val);
 
-- 
2.56.0.257.gf7497c7d27-goog