Commit d72cca1e authored Feb 14, 2013 by Grant Likely Committed by Greg Kroah-Hartman Feb 15, 2013

drivercore: Fix ordering between deferred_probe and exiting initcalls



One of the side effects of deferred probe is that some drivers which
used to be probed before initcalls completed are now happening slightly
later. This causes two problems.
- If a console driver gets deferred, then it may not be ready when
  userspace starts. For example, if a uart depends on pinctrl, then the
  uart will get deferred and /dev/console will not be available
- __init sections will be discarded before built-in drivers are probed.
  Strictly speaking, __init functions should not be called in a drivers
  __probe path, but there are a lot of drivers (console stuff again)
  that do anyway. In the past it was perfectly safe to do so because all
  built-in drivers got probed before the end of initcalls.

This patch fixes the problem by forcing the first pass of the deferred
list to complete at late_initcall time. This is late enough to catch the
drivers that are known to have the above issues.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable <stable@vger.kernel.org> # 3.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3213f631

drivers/base/dd.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -172,6 +172,8 @@ static int deferred_probe_initcall(void)

		driver_deferred_probe_enable = true;
		driver_deferred_probe_trigger();
		/* Sort as many dependencies as possible before exiting initcalls */
		flush_workqueue(deferred_wq);
		return 0;
		}
		late_initcall(deferred_probe_initcall);

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