Author: kevans
Date: Mon Nov 23 02:49:53 2020
New Revision: 367944
URL: https://svnweb.freebsd.org/changeset/base/367944
Log:
cpuset_setproc: use the appropriate parent for new anonymous sets
As far as I can tell, this has been the case since initially committed in
2008. cpuset_setproc is the executor of cpuset reassignment; note this
excerpt from the description:
* 1) Set is non-null. This reparents all anonymous sets to the provided
* set and replaces all non-anonymous td_cpusets with the provided set.
However, reviewing cpuset_setproc_setthread() for some jail related work
unearthed the error: if tdset was not anonymous, we were replacing it with
`set`. If it was anonymous, then we'd rebase it onto `set` (i.e. copy the
thread's mask over and AND it with `set`) but give the new anonymous set
the original tdset as the parent (i.e. the base of the set we're supposed to
be leaving behind).
The primary visible consequences were that:
1.) cpuset_getid() following such assignment returns the wrong result, the
setid that we left behind rather than the one we joined.
2.) When a process attached to the jail, the base set of any anonymous
threads was a set outside of the jail.
This was initially bundled in D27298, but it's a minor fix that's fairly
easy to verify the correctness of.
A test is included in D27307 ("badparent"), which demonstrates the issue
with, effectively:
osetid = cpuset_getid()
newsetid = cpuset()
cpuset_setaffinity(thread)
cpuset_setid(osetid)
cpuset_getid(thread) -> observe that it matches newsetid instead of osetid.
MFC after: 1 week
Modified:
head/sys/kern/kern_cpuset.c
Modified: head/sys/kern/kern_cpuset.c
==============================================================================
--- head/sys/kern/kern_cpuset.c Mon Nov 23 00:58:14 2020 (r367943)
+++ head/sys/kern/kern_cpuset.c Mon Nov 23 02:49:53 2020 (r367944)
@@ -1090,7 +1090,7 @@ cpuset_setproc_setthread(struct cpuset *tdset, struct
if (error)
return (error);
- return cpuset_shadow(tdset, nsetp, &mask, &domain, freelist,
+ return cpuset_shadow(set, nsetp, &mask, &domain, freelist,
domainlist);
}
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