linux-kernel - Re: [PATCH] make hci_notifier a blocking notifier (was Re: BUG: sleeping function called from invalid context at net/core/sock.c:1523)

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Message-ID: <2c0942db0705061615i1c6147a1h6aca54012c3509aa@mail.gmail.com>
Date:	Sun, 6 May 2007 16:15:00 -0700
From:	"Ray Lee" <ray-lk@...rabbit.org>
To:	"Alan Stern" <stern@...land.harvard.edu>
Cc:	"Satyam Sharma" <satyam.sharma@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Pavel Machek" <pavel@...e.cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
	"Max Krasnyansky" <maxk@...lcomm.com>, marcel@...tmann.org,
	"pm list" <linux-pm@...ts.linux-foundation.org>
Subject: Re: [PATCH] make hci_notifier a blocking notifier (was Re: BUG: sleeping function called from invalid context at net/core/sock.c:1523)

On 5/6/07, Alan Stern <stern@...land.harvard.edu> wrote:
> On Sun, 6 May 2007, Satyam Sharma wrote:
>
> > Anyway, the hci_notifier is called from the following six call sites:
> >
> > hci_dev_open() and hci_dev_close() -> both called from
> > hci_sock_ioctl() => both can sleep
> > hci_register_dev() and hci_unregister_dev() => again both are capable
> > of sleeping
> > hci_suspend_dev() and hci_resume_dev() -> called from the .suspend()
> > and .resume() of the hci_usb_driver, and again both of these can sleep
> >
> > Is there any other reason why hci_notifier must be an atomic notifier?
> >
> > (CC'ing Alan Stern just in case, apparently hci_notifier became atomic
> > when notifier chains were classified into atomic / blocking)
>
> I don't remember exactly why this particular choice was made.  Perhaps we
> found that the notifier callout routines didn't use any blocking
> primitives (we may have been mistaken about this -- there was a lot of
> code to check) and so therefore the choice didn't matter.  In that case we
> probably just decided to make it an atomic notifier to keep things simple.
>
> As you found, changing it to a blocking notifier is very easy.  Provided
> all the callers are non-atomic it should work just fine.

Okay, I'll go ahead and try the patch, then, and report back.

Thanks,

Ray
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