Patchwork [3.5.y.z,extended,stable] Patch "drivercore: Fix ordering between deferred_probe and exiting" has been added to staging queue

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Submitter Luis Henriques
Date Feb. 26, 2013, 4:14 p.m.
Message ID <1361895274-28868-1-git-send-email-luis.henriques@canonical.com>
Download mbox | patch
Permalink /patch/223331/
State New
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Luis Henriques - Feb. 26, 2013, 4:14 p.m.
This is a note to let you know that I have just added a patch titled

    drivercore: Fix ordering between deferred_probe and exiting

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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From ce5dd6f6d9d809c3a048270f380fa44852a0fce5 Mon Sep 17 00:00:00 2001
From: Grant Likely <grant.likely@secretlab.ca>
Date: Thu, 14 Feb 2013 18:14:27 +0000
Subject: [PATCH] drivercore: Fix ordering between deferred_probe and exiting
 initcalls

commit d72cca1eee5b26e313da2a380d4862924e271031 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/base/dd.c | 2 ++
 1 file changed, 2 insertions(+)

--
1.8.1.2

Patch

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 4b01ab3..82ff801 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -161,6 +161,8 @@  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);