linux-kernel - Re: [PATCH 3/3] driver/core: Fix build error when SRCU and lockdep disabled

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Date:   Mon, 12 Aug 2019 07:02:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org, kbuild test robot <lkp@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Josh Triplett <josh@...htriplett.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        linux-doc@...r.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>, rcu@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 3/3] driver/core: Fix build error when SRCU and lockdep
 disabled

On Sun, Aug 11, 2019 at 06:11:11PM -0400, Joel Fernandes (Google) wrote:
> Properly check if lockdep lock checking is disabled at config time. If
> so, then lock_is_held() is undefined so don't do any checking.
> 
> This fix is similar to the pattern used in srcu_read_lock_held().
> 
> Link: https://lore.kernel.org/lkml/201908080026.WSAFx14k%25lkp@intel.com/
> Fixes: c9e4d3a2fee8 ("acpi: Use built-in RCU list checking for acpi_ioremaps list")

What tree is this commit in?

> Reported-by: kbuild test robot <lkp@...el.com>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> ---
> This patch is based on the -rcu dev branch.

Ah...

>  drivers/base/core.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 32cf83d1c744..fe25cf690562 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -99,7 +99,11 @@ void device_links_read_unlock(int not_used)
>  
>  int device_links_read_lock_held(void)
>  {
> -	return lock_is_held(&device_links_lock);
> +#ifdef CONFIG_DEBUG_LOCK_ALLOC
> +	return lock_is_held(&(device_links_lock.dep_map));
> +#else
> +	return 1;
> +#endif

return 1?  So the lock is always held?

confused,

greg k-h