Re: [PATCH 2/2] samples: make pidfd-metadata fail gracefully on older kernels
flat view
From: Christian Brauner <christian@brauner.io>
Date: 2019-06-24 09:50:54
Also in:
lkml
On Sun, Jun 23, 2019 at 02:28:00PM +0300, Dmitry V. Levin wrote:
Initialize pidfd to an invalid descriptor, to fail gracefully on those kernels that do not implement CLONE_PIDFD and leave pidfd unchanged. Signed-off-by: Dmitry V. Levin <redacted>
Reviewed-by: Christian Brauner <christian@brauner.io> Thank you Dmitry, queueing this up for rc7.
quoted hunk ↗ jump to hunk
--- samples/pidfd/pidfd-metadata.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)diff --git a/samples/pidfd/pidfd-metadata.c b/samples/pidfd/pidfd-metadata.c index 14b454448429..c459155daf9a 100644 --- a/samples/pidfd/pidfd-metadata.c +++ b/samples/pidfd/pidfd-metadata.c@@ -83,7 +83,7 @@ static int pidfd_metadata_fd(pid_t pid, int pidfd) int main(int argc, char *argv[]) { - int pidfd = 0, ret = EXIT_FAILURE; + int pidfd = -1, ret = EXIT_FAILURE; char buf[4096] = { 0 }; pid_t pid; int procfd, statusfd;@@ -91,7 +91,11 @@ int main(int argc, char *argv[]) pid = pidfd_clone(CLONE_PIDFD, &pidfd); if (pid < 0) - exit(ret); + err(ret, "CLONE_PIDFD"); + if (pidfd == -1) { + warnx("CLONE_PIDFD is not supported by the kernel"); + goto out; + } procfd = pidfd_metadata_fd(pid, pidfd); close(pidfd);-- ldv