linux-kernel - Re: [stable] [PATCH] module: drop the lock while waiting for module to complete initialization.

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Message-ID: <20100420132211.GA27374@kroah.com>
Date:	Tue, 20 Apr 2010 06:22:11 -0700
From:	Greg KH <greg@...ah.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Herbert Xu <herbert@...dor.hengli.com.au>,
	linux-kernel@...r.kernel.org, Brandon Philips <brandon@...p.org>,
	stable@...nel.org
Subject: Re: [stable] [PATCH] module: drop the lock while waiting for
 module to complete initialization.

On Tue, Apr 20, 2010 at 06:49:04PM +0930, Rusty Russell wrote:
> This fixes "gave up waiting for init of module libcrc32c." which
> happened at boot time due to multiple parallel module loads.
> 
> The problem was a deadlock: we wait for a module to finish
> initializing, but we keep the module_lock mutex so it can't complete.
> In particular, this could reasonably happen if a module does a
> request_module() in its initialization routine.
> 
> So we change use_module() to return an errno rather than a bool, and if
> it's -EBUSY we drop the lock and wait in the caller, then reaquire the
> lock.
> 
> Reported-by: Brandon Philips <brandon@...p.org>
> Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
> Tested-by: Brandon Philips <brandon@...p.org>
> ---

If you wish to have patches included "automatically" in the stable
kernel releases, just add:
	Cc: stable <stable@...nel.org>
to the signed-off-by area of your patch.  Then, when the patch goes into
Linus's tree, I get notified of it and can trivially add it to the
proper kernel trees.

Otherwise I need to go dig through git and watch to see if/when the
patch shows up there or not, which takes a lot of time when having to do
it for a lot of patches.

thanks,

greg k-h
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