Date: Sun, 31 Aug 2014 21:51:01 +0000 (UTC) From: Edward Tomasz Napierala <trasz@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: r270899 - stable/10/sys/fs/autofs Message-ID: <201408312151.s7VLp1Ka088739@svn.freebsd.org>
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Author: trasz Date: Sun Aug 31 21:51:01 2014 New Revision: 270899 URL: http://svnweb.freebsd.org/changeset/base/270899 Log: MFC r270399: Add comment explaining one of the quirks in autofs. Sponsored by: The FreeBSD Foundation Modified: stable/10/sys/fs/autofs/autofs.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/fs/autofs/autofs.c ============================================================================== --- stable/10/sys/fs/autofs/autofs.c Sun Aug 31 21:49:45 2014 (r270898) +++ stable/10/sys/fs/autofs/autofs.c Sun Aug 31 21:51:01 2014 (r270899) @@ -595,6 +595,14 @@ autofs_open(struct cdev *dev, int flags, { sx_xlock(&sc->sc_lock); + /* + * We must never block automountd(8) and its descendants, and we use + * session ID to determine that: we store session id of the process + * that opened the device, and then compare it with session ids + * of triggering processes. This means running a second automountd(8) + * instance would break the previous one. The check below prevents + * it from happening. + */ if (sc->sc_dev_opened) { sx_xunlock(&sc->sc_lock); return (EBUSY);
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