Date: Wed, 3 Aug 2016 07:11:19 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r303703 - head/sys/vm Message-ID: <201608030711.u737BJMS047714@repo.freebsd.org>
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Author: kib Date: Wed Aug 3 07:11:19 2016 New Revision: 303703 URL: https://svnweb.freebsd.org/changeset/base/303703 Log: Explain why swapgeom_close_ev() is delegated. Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/sys/vm/swap_pager.c Modified: head/sys/vm/swap_pager.c ============================================================================== --- head/sys/vm/swap_pager.c Wed Aug 3 07:10:09 2016 (r303702) +++ head/sys/vm/swap_pager.c Wed Aug 3 07:11:19 2016 (r303703) @@ -2431,8 +2431,9 @@ swapgeom_acquire(struct g_consumer *cp) } /* - * Remove a reference from the g_consumer. Post a close event if - * all references go away. + * Remove a reference from the g_consumer. Post a close event if all + * references go away, since the function might be called from the + * biodone context. */ static void swapgeom_release(struct g_consumer *cp, struct swdevt *sp) @@ -2555,7 +2556,12 @@ swapgeom_close(struct thread *td, struct cp = sw->sw_id; sw->sw_id = NULL; mtx_unlock(&sw_dev_mtx); - /* XXX: direct call when Giant untangled */ + + /* + * swapgeom_close() may be called from the biodone context, + * where we cannot perform topology changes. Delegate the + * work to the events thread. + */ if (cp != NULL) g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); }
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