Re: [PATCH] locking: Detect includes rwlock.h outside of spinlock.h

[Peter Zijlstra]

On Thu, Aug 25, 2022 at 06:08:56PM +0200, Sebastian Andrzej Siewior wrote:
> From: Michael S. Tsirkin <mst@xxxxxxxxxx>
> 
> The check for __LINUX_SPINLOCK_H within rwlock.h (and other files)
> detects the direct include of the header file if it is at the very
> beginning of the include section.
> If it is listed later then chances are high that spinlock.h was already
> included (including rwlock.h) and the additional listing of rwlock.h
> will not cause any failure.
> 
> On PREEMPT_RT this additional rwlock.h will lead to compile failures
> since it uses a different rwlock implementation.
> 
> Add __LINUX_INSIDE_SPINLOCK_H to spinlock.h and check for this instead
> of __LINUX_SPINLOCK_H to detect wrong includes. This will help detect
> direct includes of rwlock.h with without PREEMPT_RT enabled.
> 
> [ bigeasy: add remaining __LINUX_SPINLOCK_H user and rewrite
>   commit description. ]
> 
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

Thanks!