Re: [PATCH] drivercore: Fix ordering between deferred_probe andexiting initcalls

From: Greg Kroah-Hartman
Date: Thu Feb 14 2013 - 13:28:32 EST

On Thu, Feb 14, 2013 at 06:14:27PM +0000, Grant Likely wrote:
> 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@xxxxxxxxxxxx>
> Tested-by: Haojian Zhuang <haojian.zhuang@xxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> Hi Greg and Linus,
> Okay, so this is really late to be sending for v3.8, and it doesn't have
> nearly the amount of testing that I would like it to have. I haven't
> even put it into linux-next yet. However, it is a real bug that some of
> the Linaro folks have run into that is caused by deferred probe. It
> isn't very widespread, but it is there.
> It probably should be in v3.8, but given how ridiculously late it is and
> that it isn't a widespread problem it would probably be just fine to go
> in during the v3.9 merge window and get backported to linux-stable. If I
> don't hear otherwise then that is what I'll do.
> Still, here it is. If you think it really should be merged before
> tagging v3.8 then please go ahead and apply it.

Nah, we can wait for 3.9-rc1, I'll queue it up in my tree and push it to
Linus for then, and tag it for stable kernels to be backported at that
point in time.


greg k-h
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at