From 9029ab8ae01f315cc9ce795ad52e09013e10d893 Mon Sep 17 00:00:00 2001 From: Yu Watanabe Date: Thu, 13 Jan 2022 00:09:38 +0900 Subject: [PATCH] pid1,cgroup-show: ignore -EOPNOTSUPP in cg_read_pid() The function is called in recursion, and cgroup.procs in some subcgroups may not be read. Fixes #22089. Reference: https://github.com/systemd/systemd/pull/22095/commits/c41911ce12d23d28b090b51c200db1e1e8ee7ce7 Signed-off-by: zhaoxiaohu Signed-off-by: yuwang --- src/core/dbus-unit.c | 8 ++++++-- src/shared/cgroup-show.c | 17 ++++++++++++----- 2 files changed, 18 insertions(+), 7 deletions(-) diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c index 24e4d25..0640d3e 100644 --- a/src/core/dbus-unit.c +++ b/src/core/dbus-unit.c @@ -1295,11 +1295,15 @@ static int append_cgroup(sd_bus_message *reply, const char *p, Set *pids) { for (;;) { pid_t pid; + /* libvirt / qemu uses threaded mode and cgroup.procs cannot be read at the lower levels. + * From https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#threads, + * “cgroup.procs” in a threaded domain cgroup contains the PIDs of all processes in + * the subtree and is not readable in the subtree proper. */ r = cg_read_pid(f, &pid); + if (IN_SET(r, 0, -EOPNOTSUPP)) + break; if (r < 0) return r; - if (r == 0) - break; if (is_kernel_thread(pid) > 0) continue; diff --git a/src/shared/cgroup-show.c b/src/shared/cgroup-show.c index c7e63be..c324652 100644 --- a/src/shared/cgroup-show.c +++ b/src/shared/cgroup-show.c @@ -86,7 +86,6 @@ static int show_cgroup_one_by_path( _cleanup_fclose_ FILE *f = NULL; _cleanup_free_ char *p = NULL; size_t n = 0; - pid_t pid; char *fn; int r; @@ -99,7 +98,18 @@ static int show_cgroup_one_by_path( if (!f) return -errno; - while ((r = cg_read_pid(f, &pid)) > 0) { + for (;;) { + pid_t pid; + + /* libvirt / qemu uses threaded mode and cgroup.procs cannot be read at the lower levels. + * From https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#threads, + * “cgroup.procs” in a threaded domain cgroup contains the PIDs of all processes in + * the subtree and is not readable in the subtree proper. */ + r = cg_read_pid(f, &pid); + if (IN_SET(r, 0, -EOPNOTSUPP)) + break; + if (r < 0) + return r; if (!(flags & OUTPUT_KERNEL_THREADS) && is_kernel_thread(pid) > 0) continue; @@ -110,9 +120,6 @@ static int show_cgroup_one_by_path( pids[n++] = pid; } - if (r < 0) - return r; - show_pid_array(pids, n, prefix, n_columns, false, more, flags); return 0; -- 2.33.0