Re: [PATCH 1/5] locking: Add rwsem_is_write_locked()

Matthew Wilcox
2023-09-07T19:34:12Z

On Thu, Sep 07, 2023 at 02:05:54PM -0400, Waiman Long wrote:
> On 9/7/23 13:47, Matthew Wilcox (Oracle) wrote:
> > +static inline int rwsem_is_write_locked(struct rw_semaphore *sem)
> > +{
> > + return atomic_long_read(&sem->count) & 1 /* RWSEM_WRITER_LOCKED */;
> > +}
>
> I would prefer you move the various RWSEM_* count bit macros from
> kernel/locking/rwsem.c to under the !PREEMPT_RT block and directly use
> RWSEM_WRITER_LOCKED instead of hardcoding a value of 1.

Just to be clear, you want the ~50 lines from:

/*
* On 64-bit architectures, the bit definitions of the count are:
...
#define RWSEM_READ_FAILED_MASK (RWSEM_WRITER_MASK|RWSEM_FLAG_WAITERS|\
RWSEM_FLAG_HANDOFF|RWSEM_FLAG_READFAIL)

moved from rwsem.c to rwsem.h?

Or just these four lines:

#define RWSEM_WRITER_LOCKED (1UL << 0)
#define RWSEM_FLAG_WAITERS (1UL << 1)
#define RWSEM_FLAG_HANDOFF (1UL << 2)
#define RWSEM_FLAG_READFAIL (1UL << (BITS_PER_LONG - 1))