lock(&sched.deferlock)
	// disconnect cached list before dropping it on the floor,
	// so that a dangling ref to one entry does not pin all of them.
	var d, dlink *_defer
	for d = sched.deferpool; d != nil; d = dlink {
		dlink = d.link
		d.link = nil
	}
	sched.deferpool = nil
	unlock(&sched.deferlock)
}

// Timing

	39:  "level 3 halted",
	40:  "level 3 reset",
	41:  "link number out of range",
	42:  "protocol driver not attached",
	43:  "no CSI structure available",
	44:  "level 2 halted",
	45:  "deadlock situation detected/avoided",
	46:  "no record locks available",
	47:  "operation canceled",
	48:  "operation not supported",
	49:  "disc quota exceeded",
	50:  "bad exchange descriptor",

	{41, "ELNRNG", "link number out of range"},
	{42, "EUNATCH", "protocol driver not attached"},
	{43, "ENOCSI", "no CSI structure available"},
	{44, "EL2HLT", "level 2 halted"},
	{45, "EDEADLK", "deadlock situation detected/avoided"},
	{46, "ENOLCK", "no record locks available"},
	{47, "ECANCELED", "operation canceled"},
	{48, "ENOTSUP", "operation not supported"},
	{49, "EDQUOT", "disc quota exceeded"},

	43:   "no CSI structure available",
	44:   "level 2 halted",
	45:   "resource deadlock avoided",
	46:   "no locks available",
	50:   "invalid exchange",
	51:   "invalid request descriptor",
	52:   "exchange full",
	53:   "no anode",
	54:   "invalid request code",
	55:   "invalid slot",
	56:   "file locking deadlock error",
	59:   "bad font file format",
	60:   "device not a stream",

	43:   "no CSI structure available",
	44:   "level 2 halted",
	45:   "resource deadlock avoided",
	46:   "no locks available",
	50:   "invalid exchange",
	51:   "invalid request descriptor",
	52:   "exchange full",
	53:   "no anode",
	54:   "invalid request code",
	55:   "invalid slot",
	56:   "file locking deadlock error",
	59:   "bad font file format",
	60:   "device not a stream",

	43:   "no CSI structure available",
	44:   "level 2 halted",
	45:   "resource deadlock avoided",
	46:   "no locks available",
	50:   "invalid exchange",
	51:   "invalid request descriptor",
	52:   "exchange full",
	53:   "no anode",
	54:   "invalid request code",
	55:   "invalid slot",
	56:   "file locking deadlock error",
	59:   "bad font file format",
	60:   "device not a stream",

	43:   "no CSI structure available",
	44:   "level 2 halted",
	45:   "resource deadlock avoided",
	46:   "no locks available",
	50:   "invalid exchange",
	51:   "invalid request descriptor",
	52:   "exchange full",
	53:   "no anode",
	54:   "invalid request code",
	55:   "invalid slot",
	56:   "file locking deadlock error",
	59:   "bad font file format",
	60:   "device not a stream",

	29:  "illegal seek",
	30:  "read-only file system",
	31:  "too many links",
	32:  "broken pipe",
	33:  "numerical argument out of domain",
	34:  "numerical result out of range",
	35:  "resource deadlock avoided",
	36:  "file name too long",
	37:  "no locks available",
	38:  "function not implemented",
	39:  "directory not empty",
	40:  "too many levels of symbolic links",
	42:  "no message of desired type",

	29:  "illegal seek",
	30:  "read-only file system",
	31:  "too many links",
	32:  "broken pipe",
	33:  "numerical argument out of domain",
	34:  "numerical result out of range",
	35:  "resource deadlock avoided",
	36:  "file name too long",
	37:  "no locks available",
	38:  "function not implemented",
	39:  "directory not empty",
	40:  "too many levels of symbolic links",
	42:  "no message of desired type",

		pred.AllowWatchBookmarks,
		c.groupResource,
		identifier,
	)

	// note that c.waitUntilWatchCacheFreshAndForceAllEvents must be called without
	// the c.watchCache.RLock held otherwise we are at risk of a deadlock
	// mainly because c.watchCache.processEvent method won't be able to make progress
	//
	// moreover even though the c.waitUntilWatchCacheFreshAndForceAllEvents acquires a lock