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From: Fiona Ebner <f.ebner@proxmox.com>
To: pve-devel@lists.proxmox.com
Date: Mon, 10 Jul 2023 10:52:59 +0200
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Subject: [pve-devel] [PATCH v2 qemu-server 1/4] qmeventd: improve getting
VMID from PID in presence of legacy cgroup entries
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On a hybrid cgroup system, the /proc/<PID>/cgroup file looks like
> 13:pids:/qemu.slice/110.scope
> 12:perf_event:/
> 11:devices:/qemu.slice
> 10:misc:/
> 9:hugetlb:/
> 8:freezer:/
> 7:cpu,cpuacct:/qemu.slice/110.scope
> 6:memory:/qemu.slice/110.scope
> 5:rdma:/
> 4:cpuset:/
> 3:blkio:/qemu.slice
> 2:net_cls,net_prio:/
> 1:name=systemd:/qemu.slice/110.scope
> 0::/qemu.slice/110.scope
but the order doesn't seem to be deterministic, so it can happen that
an entry like '11:devices:/qemu.slice' is the first to match the
'/qemu.slice' part, which previously made the code expect to find the
VMID.
To improve detection, as a first step, match the trailing slash too.
Reported in the community forum:
https://forum.proxmox.com/threads/129320/post-571654
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
Changes in v2:
* Improve commit message, seems like the order is not the same on
every boot.
qmeventd/qmeventd.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/qmeventd/qmeventd.c b/qmeventd/qmeventd.c
index 921c0dca..503bce69 100644
--- a/qmeventd/qmeventd.c
+++ b/qmeventd/qmeventd.c
@@ -109,7 +109,7 @@ get_vmid_from_pid(pid_t pid)
}
cgroup_path++;
- if (strncmp(cgroup_path, "/qemu.slice", 11)) {
+ if (strncmp(cgroup_path, "/qemu.slice/", 12)) {
continue;
}
@@ -142,7 +142,7 @@ get_vmid_from_pid(pid_t pid)
if (errno) {
fprintf(stderr, "error parsing vmid for %d: %s\n", pid, strerror(errno));
} else {
- fprintf(stderr, "error parsing vmid for %d: no qemu.slice cgroup entry\n", pid);
+ fprintf(stderr, "error parsing vmid for %d: no matching qemu.slice cgroup entry\n", pid);
}
ret:
--
2.39.2