3.16.61-rc1 review patch. If anyone has any objections, please let me know.
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From: Arnaldo Carvalho de Melo acme@redhat.com
commit 7093b4c963cc4e344e490c774924a180602a7092 upstream.
The readdir() function is thread safe as long as just one thread uses a DIR, which is the case when synthesizing events for pre-existing threads by traversing /proc, so, to avoid breaking the build with glibc-2.23.90 (upcoming 2.24), use it instead of readdir_r().
See: http://man7.org/linux/man-pages/man3/readdir.3.html
"However, in modern implementations (including the glibc implementation), concurrent calls to readdir() that specify different directory streams are thread-safe. In cases where multiple threads must read from the same directory stream, using readdir() with external synchronization is still preferable to the use of the deprecated readdir_r(3) function."
Noticed while building on a Fedora Rawhide docker container.
CC /tmp/build/perf/util/event.o util/event.c: In function '__event__synthesize_thread': util/event.c:466:2: error: 'readdir_r' is deprecated [-Werror=deprecated-declarations] while (!readdir_r(tasks, &dirent, &next) && next) { ^~~~~ In file included from /usr/include/features.h:368:0, from /usr/include/stdint.h:25, from /usr/lib/gcc/x86_64-redhat-linux/6.0.0/include/stdint.h:9, from /git/linux/tools/include/linux/types.h:6, from util/event.c:1: /usr/include/dirent.h:189:12: note: declared here
Cc: Adrian Hunter adrian.hunter@intel.com Cc: David Ahern dsahern@gmail.com Cc: Jiri Olsa jolsa@kernel.org Cc: Namhyung Kim namhyung@kernel.org Cc: Wang Nan wangnan0@huawei.com Link: http://lkml.kernel.org/n/tip-i1vj7nyjp2p750rirxgrfd3c@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- tools/perf/util/event.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
--- a/tools/perf/util/event.c +++ b/tools/perf/util/event.c @@ -331,7 +331,7 @@ static int __event__synthesize_thread(un { char filename[PATH_MAX]; DIR *tasks; - struct dirent dirent, *next; + struct dirent *dirent; pid_t tgid;
/* special case: only send one comm event using passed in pid */ @@ -358,12 +358,12 @@ static int __event__synthesize_thread(un return 0; }
- while (!readdir_r(tasks, &dirent, &next) && next) { + while ((dirent = readdir(tasks)) != NULL) { char *end; int rc = 0; pid_t _pid;
- _pid = strtol(dirent.d_name, &end, 10); + _pid = strtol(dirent->d_name, &end, 10); if (*end) continue;
@@ -464,7 +464,7 @@ int perf_event__synthesize_threads(struc { DIR *proc; char proc_path[PATH_MAX]; - struct dirent dirent, *next; + struct dirent *dirent; union perf_event *comm_event, *mmap_event, *fork_event; int err = -1;
@@ -489,9 +489,9 @@ int perf_event__synthesize_threads(struc if (proc == NULL) goto out_free_fork;
- while (!readdir_r(proc, &dirent, &next) && next) { + while ((dirent = readdir(proc)) != NULL) { char *end; - pid_t pid = strtol(dirent.d_name, &end, 10); + pid_t pid = strtol(dirent->d_name, &end, 10);
if (*end) /* only interested in proper numerical dirents */ continue;