[PATCH 2/2] perf/tools: put new buildid locks to use

[Milos Vyletel]

Use new read/write locks when accesing buildid directory on places where
we may race if multiple instances are run simultaneously.

Signed-off-by: Milos Vyletel <milos@xxxxxxxxxx>
---
 tools/perf/builtin-buildid-cache.c | 12 +++++++++++
 tools/perf/util/build-id.c         | 41 ++++++++++++++++++++++++++++++--------
 2 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
index d47a0cd..4cf0a1d 100644
--- a/tools/perf/builtin-buildid-cache.c
+++ b/tools/perf/builtin-buildid-cache.c
@@ -94,8 +94,13 @@ static int build_id_cache__kcore_existing(const char *from_dir, char *to_dir,
 	char to_subdir[PATH_MAX];
 	struct dirent *dent;
 	int ret = -1;
+	int lockfd;
 	DIR *d;
 
+	buildid_dir_read_lock(&lockfd);
+	if (lockfd == -1)
+		return -1;
+
 	d = opendir(to_dir);
 	if (!d)
 		return -1;
@@ -121,6 +126,7 @@ static int build_id_cache__kcore_existing(const char *from_dir, char *to_dir,
 	}
 
 	closedir(d);
+	buildid_dir_read_unlock(lockfd);
 
 	return ret;
 }
@@ -130,6 +136,7 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
 	char dir[32], sbuildid[BUILD_ID_SIZE * 2 + 1];
 	char from_dir[PATH_MAX], to_dir[PATH_MAX];
 	char *p;
+	int lockfd;
 
 	strlcpy(from_dir, filename, sizeof(from_dir));
 
@@ -156,6 +163,10 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
 	scnprintf(to_dir, sizeof(to_dir), "%s/[kernel.kcore]/%s/%s",
 		  buildid_dir, sbuildid, dir);
 
+	buildid_dir_write_lock(&lockfd);
+	if (lockfd == -1)
+		return -1;
+
 	if (mkdir_p(to_dir, 0755))
 		return -1;
 
@@ -176,6 +187,7 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
 		}
 		return -1;
 	}
+	buildid_dir_write_unlock(lockfd);
 
 	pr_debug("kcore added to build-id cache directory %s\n", to_dir);
 
diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 46c41e1..13d23aa 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -17,6 +17,7 @@
 #include "tool.h"
 #include "header.h"
 #include "vdso.h"
+#include <sys/file.h>
 
 
 static bool no_buildid_cache;
@@ -308,6 +309,7 @@ int build_id_cache__list_build_ids(const char *pathname,
 	DIR *dir;
 	struct dirent *d;
 	int ret = 0;
+	int lockfd = -1;
 
 	list = strlist__new(true, NULL);
 	dir_name = build_id_cache__dirname_from_path(pathname, false, false);
@@ -316,11 +318,17 @@ int build_id_cache__list_build_ids(const char *pathname,
 		goto out;
 	}
 
+	buildid_dir_read_lock(&lockfd);
+	if (lockfd == -1) {
+		ret = -errno;
+		goto out;
+	}
+
 	/* List up all dirents */
 	dir = opendir(dir_name);
 	if (!dir) {
 		ret = -errno;
-		goto out;
+		goto out_unlock;
 	}
 
 	while ((d = readdir(dir)) != NULL) {
@@ -330,6 +338,8 @@ int build_id_cache__list_build_ids(const char *pathname,
 	}
 	closedir(dir);
 
+out_unlock:
+	buildid_dir_read_unlock(lockfd);
 out:
 	free(dir_name);
 	if (ret)
@@ -347,6 +357,7 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
 	char *realname = NULL, *filename = NULL, *dir_name = NULL,
 	     *linkname = zalloc(size), *targetname, *tmp;
 	int err = -1;
+	int lockfd;
 
 	if (!is_kallsyms) {
 		realname = realpath(name, NULL);
@@ -358,30 +369,34 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
 	if (!dir_name)
 		goto out_free;
 
-	if (mkdir_p(dir_name, 0755))
+	buildid_dir_write_lock(&lockfd);
+	if (lockfd == -1)
 		goto out_free;
 
+	if (mkdir_p(dir_name, 0755))
+		goto out_unlock;
+
 	if (asprintf(&filename, "%s/%s", dir_name, sbuild_id) < 0) {
 		filename = NULL;
-		goto out_free;
+		goto out_unlock;
 	}
 
 	if (access(filename, F_OK)) {
 		if (is_kallsyms) {
 			 if (copyfile("/proc/kallsyms", filename))
-				goto out_free;
+				goto out_unlock;
 		} else if (link(realname, filename) && errno != EEXIST &&
 				copyfile(name, filename))
-			goto out_free;
+			goto out_unlock;
 	}
 
 	if (!build_id__filename(sbuild_id, linkname, size))
-		goto out_free;
+		goto out_unlock;
 	tmp = strrchr(linkname, '/');
 	*tmp = '\0';
 
 	if (access(linkname, X_OK) && mkdir_p(linkname, 0755))
-		goto out_free;
+		goto out_unlock;
 
 	*tmp = '/';
 	targetname = filename + strlen(buildid_dir) - 5;
@@ -389,6 +404,8 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
 
 	if (symlink(targetname, linkname) == 0)
 		err = 0;
+out_unlock:
+	buildid_dir_write_unlock(lockfd);
 out_free:
 	if (!is_kallsyms)
 		free(realname);
@@ -427,6 +444,7 @@ int build_id_cache__remove_s(const char *sbuild_id)
 	char *filename = zalloc(size),
 	     *linkname = zalloc(size), *tmp;
 	int err = -1;
+	int lockfd = -1;
 
 	if (filename == NULL || linkname == NULL)
 		goto out_free;
@@ -449,10 +467,17 @@ int build_id_cache__remove_s(const char *sbuild_id)
 	tmp = strrchr(linkname, '/') + 1;
 	snprintf(tmp, size - (tmp - linkname), "%s", filename);
 
-	if (unlink(linkname))
+	buildid_dir_write_lock(&lockfd);
+	if (lockfd == -1)
 		goto out_free;
 
+	if (unlink(linkname))
+		goto out_unlock;
+
+
 	err = 0;
+out_unlock:
+	buildid_dir_write_unlock(lockfd);
 out_free:
 	free(filename);
 	free(linkname);
-- 
2.4.0

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