Date: Wed, 16 Sep 2015 04:35:24 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r287849 - stable/10/sys/kern Message-ID: <201509160435.t8G4ZOGm082431@repo.freebsd.org>
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Author: kib Date: Wed Sep 16 04:35:23 2015 New Revision: 287849 URL: https://svnweb.freebsd.org/changeset/base/287849 Log: MFC r287366: Use SLIST_FOREACH_SAFE() to fix iteration. Modified: stable/10/sys/kern/kern_event.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/kern/kern_event.c ============================================================================== --- stable/10/sys/kern/kern_event.c Wed Sep 16 04:27:12 2015 (r287848) +++ stable/10/sys/kern/kern_event.c Wed Sep 16 04:35:23 2015 (r287849) @@ -1849,7 +1849,7 @@ void knote(struct knlist *list, long hint, int lockflags) { struct kqueue *kq; - struct knote *kn; + struct knote *kn, *tkn; int error; if (list == NULL) @@ -1861,14 +1861,13 @@ knote(struct knlist *list, long hint, in list->kl_lock(list->kl_lockarg); /* - * If we unlock the list lock (and set KN_INFLUX), we can eliminate - * the kqueue scheduling, but this will introduce four - * lock/unlock's for each knote to test. If we do, continue to use - * SLIST_FOREACH, SLIST_FOREACH_SAFE is not safe in our case, it is - * only safe if you want to remove the current item, which we are - * not doing. + * If we unlock the list lock (and set KN_INFLUX), we can + * eliminate the kqueue scheduling, but this will introduce + * four lock/unlock's for each knote to test. Also, marker + * would be needed to keep iteration position, since filters + * or other threads could remove events. */ - SLIST_FOREACH(kn, &list->kl_list, kn_selnext) { + SLIST_FOREACH_SAFE(kn, &list->kl_list, kn_selnext, tkn) { kq = kn->kn_kq; KQ_LOCK(kq); if ((kn->kn_status & (KN_INFLUX | KN_SCAN)) == KN_INFLUX) {
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