Re: usage of DEFINE_WAIT_OVERRIDE_MAP(LD_WAIT_SLEEP)

[Sebastian Andrzej Siewior]

On 2025-10-23 17:53:40 [+0200], Oleg Nesterov wrote:
> Sebastian,
Hi Oleg,

> sorry. I guess this is my fault, but I can't understand your reply...
> Could you spell please?

So you refer to this:
| /* PREEMPT_RT kernels map spinlock to rt_mutex */
| #include <linux/rtmutex.h>
| 
| typedef struct spinlock {
| 	struct rt_mutex_base	lock;
| #ifdef CONFIG_DEBUG_LOCK_ALLOC
| 	struct lockdep_map	dep_map;
| #endif
| } spinlock_t;

spinlock_t on PREEMPT_RT does not use (struct) rt_mutex as the comment
claims. It uses just the basic building block which is "struct
rt_mutex_base". This requires linux/rtmutex.h. 

spinlock_t on PREEMPT_RT uses LD_WAIT_CONFIG via SPIN_DEP_MAP_INIT as
!PREEMPT_RT. Nothing changes here.

struct rt_mutex on the other hand uses LD_WAIT_SLEEP and this one is
like struct mutex but with PI.

Sebastian