From: Grant Likely <grant.likely@secretlab.ca>
To: Haojian Zhuang <haojian.zhuang@linaro.org>,
gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk,
rusty@rustcorp.com.au, hpa@linux.intel.com, jim.cromie@gmail.com,
linux-kernel@vger.kernel.org, linux@arm.linux.org.uk,
linus.walleij@linaro.org, arnd@arndb.de,
broonie@opensource.wolfsonmicro.com, akpm@linux-foundation.org
Cc: patches@linaro.org, Haojian Zhuang <haojian.zhuang@linaro.org>
Subject: Re: [PATCH v2] driver core: add wait event for deferred probe
Date: Wed, 13 Feb 2013 21:39:59 +0000 [thread overview]
Message-ID: <20130213213959.BE1D53E3557@localhost> (raw)
In-Reply-To: <1360637915-11212-1-git-send-email-haojian.zhuang@linaro.org>
On Tue, 12 Feb 2013 10:58:35 +0800, Haojian Zhuang <haojian.zhuang@linaro.org> wrote:
> do_initcalls() could call all driver initialization code in kernel_init
> thread. It means that probe() function will be also called from that
> time. After this, kernel could access console & release __init section
> in the same thread.
>
> But if device probe fails and moves into deferred probe list, a new
> thread is created to reinvoke probe. If the device is serial console,
> kernel has to open console failure & release __init section before
> reinvoking failure. Because there's no synchronization mechanism.
> Now add wait event to synchronize after do_initcalls().
>
> Changelog:
> v2: add comments on wait_for_device_probe().
>
> Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
As replied to on v1 of your patch, this change will cause a deadlock.
The following change would do the same without the deadlock issue:
static int deferred_probe_initcall(void)
{
deferred_wq = create_singlethread_workqueue("deferwq");
if (WARN_ON(!deferred_wq))
return -ENOMEM;
driver_deferred_probe_enable = true;
+ deferred_probe_work_func(NULL);
- driver_deferred_probe_trigger();
return 0;
}
late_initcall(deferred_probe_initcall);
g.
prev parent reply other threads:[~2013-02-13 21:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-12 2:58 [PATCH v2] driver core: add wait event for deferred probe Haojian Zhuang
2013-02-13 16:41 ` anish kumar
2013-02-13 21:39 ` Grant Likely [this message]
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