Author: kevans Date: Sat Nov 28 01:21:11 2020 New Revision: 368116 URL: https://svnweb.freebsd.org/changeset/base/368116
Log: kern: cpuset: drop the lock to allocate domainsets Restructure the loop a little bit to make it a little more clear how it really operates: we never allocate any domains at the beginning of the first iteration, and it will run until we've satisfied the amount we need or we encounter an error. The lock is now taken outside of the loop to make stuff inside the loop easier to evaluate w.r.t. locking. This fixes it to not try and allocate any domains for the freelist under the spinlock, which would have happened before if we needed any new domains. Reported by: syzbot+6743fa07b9b7528dc...@syzkaller.appspotmail.com Reviewed by: markj MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D27371 Modified: head/sys/kern/kern_cpuset.c Modified: head/sys/kern/kern_cpuset.c ============================================================================== --- head/sys/kern/kern_cpuset.c Sat Nov 28 01:16:59 2020 (r368115) +++ head/sys/kern/kern_cpuset.c Sat Nov 28 01:21:11 2020 (r368116) @@ -794,14 +794,11 @@ cpuset_modify_domain(struct cpuset *set, struct domain return (EPERM); domainset_freelist_init(&domains, 0); domain = domainset_create(domain); - ndomains = needed = 0; - do { - if (ndomains < needed) { - domainset_freelist_add(&domains, needed - ndomains); - ndomains = needed; - } + ndomains = 0; + + mtx_lock_spin(&cpuset_lock); + for (;;) { root = cpuset_getroot(set); - mtx_lock_spin(&cpuset_lock); dset = root->cs_domain; /* * Verify that we have access to this set of domains. @@ -826,7 +823,15 @@ cpuset_modify_domain(struct cpuset *set, struct domain &needed, 0); if (error) goto out; - } while (ndomains < needed); + if (ndomains >= needed) + break; + + /* Dropping the lock; we'll need to re-evaluate again. */ + mtx_unlock_spin(&cpuset_lock); + domainset_freelist_add(&domains, needed - ndomains); + ndomains = needed; + mtx_lock_spin(&cpuset_lock); + } dset = set->cs_domain; cpuset_update_domain(set, domain, dset, &domains); out: _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
