From ce2bfb856987526c2f27fb934b5eedd70d3472d7 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Netto Date: Thu, 24 Aug 2023 13:42:17 -0300 Subject: linux: Add posix_spawnattr_{get, set}cgroup_np (BZ 26371) These functions allow to posix_spawn and posix_spawnp to use CLONE_INTO_CGROUP with clone3, allowing the child process to be created in a different cgroup version 2. These are GNU extensions that are available only for Linux, and also only for the architectures that implement clone3 wrapper (HAVE_CLONE3_WRAPPER). To create a process on a different cgroupv2, one can use the: posix_spawnattr_t attr; posix_spawnattr_init (&attr); posix_spawnattr_setflags (&attr, POSIX_SPAWN_SETCGROUP); posix_spawnattr_setcgroup_np (&attr, cgroup); posix_spawn (...) Similar to other posix_spawn flags, POSIX_SPAWN_SETCGROUP control whether the cgroup file descriptor will be used or not with clone3. There is no fallback if either clone3 does not support the flag or if the architecture does not provide the clone3 wrapper, in this case posix_spawn returns EOPNOTSUPP. Checked on x86_64-linux-gnu. Reviewed-by: Florian Weimer --- sysdeps/unix/sysv/linux/spawni.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) (limited to 'sysdeps/unix/sysv/linux/spawni.c') diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c index ec687cb423..f0d4c62ae6 100644 --- a/sysdeps/unix/sysv/linux/spawni.c +++ b/sysdeps/unix/sysv/linux/spawni.c @@ -380,14 +380,19 @@ __spawnix (pid_t * pid, const char *file, need for CLONE_SETTLS. Although parent and child share the same TLS namespace, there will be no concurrent access for TLS variables (errno for instance). */ + bool set_cgroup = attrp ? (attrp->__flags & POSIX_SPAWN_SETCGROUP) : false; struct clone_args clone_args = { /* Unsupported flags like CLONE_CLEAR_SIGHAND will be cleared up by __clone_internal_fallback. */ - .flags = CLONE_CLEAR_SIGHAND | CLONE_VM | CLONE_VFORK, + .flags = (set_cgroup ? CLONE_INTO_CGROUP : 0) + | CLONE_CLEAR_SIGHAND + | CLONE_VM + | CLONE_VFORK, .exit_signal = SIGCHLD, .stack = (uintptr_t) stack, .stack_size = stack_size, + .cgroup = (set_cgroup ? attrp->__cgroup : 0) }; #ifdef HAVE_CLONE3_WRAPPER args.use_clone3 = true; @@ -398,8 +403,19 @@ __spawnix (pid_t * pid, const char *file, #endif { args.use_clone3 = false; - new_pid = __clone_internal_fallback (&clone_args, __spawni_child, - &args); + if (!set_cgroup) + new_pid = __clone_internal_fallback (&clone_args, __spawni_child, + &args); + else + { + /* No fallback for POSIX_SPAWN_SETCGROUP if clone3 is not + supported. */ + new_pid = -1; +#ifdef HAVE_CLONE3_WRAPPER + if (errno == ENOSYS) +#endif + errno = ENOTSUP; + } } /* It needs to collect the case where the auxiliary process was created -- cgit v1.2.3-70-g09d2