Re: qemu-kvm hangs at start up under 3.8.0-rc3-00074-gb719f43(works with CONFIG_LOCKDEP)

[Andrew Clayton]

On Tue, 15 Jan 2013 19:41:32 +0100 (CET), Jiri Kosina wrote:

[snip]

> Could you please try the patch below and report backt? Thanks.
> 
> 
> 
> From: Jiri Kosina <jkosina@xxxxxxx>
> Subject: [PATCH] lockdep, rwsem: fix down_write_nest_lock()
> if !CONFIG_DEBUG_LOCK_ALLOC
> 
> Commit 1b963c81b1 ("lockdep, rwsem: provide down_write_nest_lock()") 
> contains a bug in a codepath when CONFIG_DEBUG_LOCK_ALLOC is
> disabled, which causes down_read() to be called instead of
> down_write() by mistake on such configurations. Fix that.
> 
> Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
> ---
>  include/linux/rwsem.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
> index 413cc11..8da67d6 100644
> --- a/include/linux/rwsem.h
> +++ b/include/linux/rwsem.h
> @@ -135,7 +135,7 @@ do
> {								\ 
>  #else
>  # define down_read_nested(sem, subclass)
> down_read(sem) -# define down_write_nest_lock(sem, nest_lock)
> down_read(sem) +# define down_write_nest_lock(sem, nest_lock)
> down_write(sem) # define down_write_nested(sem, subclass)
> down_write(sem) #endif
>  

Heh, indeed, that fix's it.

Tested-by: Andrew Clayton <andrew@xxxxxxxxxxxxxxxxxx>

Cheers,
Andrew
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