Re: [PATCH 15/15] seqlock: drop seqcount_ww_mutex_t

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Apr 07, 2022 at 10:59:46AM +0200, Christian König wrote:
> Daniel pointed out that this series removes the last user of
> seqcount_ww_mutex_t, so let's drop this.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Waiman Long <longman@redhat.com>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: linux-kernel@vger.kernel.org

Yeah I don't think we'll ever need this again, ww_mutex aren't common and
the ww_mutex+seqlock thing wasn't the brighest idea.

Peter/Ingo, assuming you agree, can you ack this for merging through
drm-misc, or want to pick this up later on when the last user disappeared
in Linus' tree?

Cheers, Daniel

> ---
>  include/linux/seqlock.h | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
> index 37ded6b8fee6..3926e9027947 100644
> --- a/include/linux/seqlock.h
> +++ b/include/linux/seqlock.h
> @@ -17,7 +17,6 @@
>  #include <linux/kcsan-checks.h>
>  #include <linux/lockdep.h>
>  #include <linux/mutex.h>
> -#include <linux/ww_mutex.h>
>  #include <linux/preempt.h>
>  #include <linux/spinlock.h>
>  
> @@ -164,7 +163,7 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s)
>   * static initializer or init function. This enables lockdep to validate
>   * that the write side critical section is properly serialized.
>   *
> - * LOCKNAME:	raw_spinlock, spinlock, rwlock, mutex, or ww_mutex.
> + * LOCKNAME:	raw_spinlock, spinlock, rwlock or mutex
>   */
>  
>  /*
> @@ -184,7 +183,6 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s)
>  #define seqcount_spinlock_init(s, lock)		seqcount_LOCKNAME_init(s, lock, spinlock)
>  #define seqcount_rwlock_init(s, lock)		seqcount_LOCKNAME_init(s, lock, rwlock)
>  #define seqcount_mutex_init(s, lock)		seqcount_LOCKNAME_init(s, lock, mutex)
> -#define seqcount_ww_mutex_init(s, lock)		seqcount_LOCKNAME_init(s, lock, ww_mutex)
>  
>  /*
>   * SEQCOUNT_LOCKNAME()	- Instantiate seqcount_LOCKNAME_t and helpers
> @@ -277,7 +275,6 @@ SEQCOUNT_LOCKNAME(raw_spinlock, raw_spinlock_t,  false,    s->lock,        raw_s
>  SEQCOUNT_LOCKNAME(spinlock,     spinlock_t,      __SEQ_RT, s->lock,        spin,     spin_lock(s->lock))
>  SEQCOUNT_LOCKNAME(rwlock,       rwlock_t,        __SEQ_RT, s->lock,        read,     read_lock(s->lock))
>  SEQCOUNT_LOCKNAME(mutex,        struct mutex,    true,     s->lock,        mutex,    mutex_lock(s->lock))
> -SEQCOUNT_LOCKNAME(ww_mutex,     struct ww_mutex, true,     &s->lock->base, ww_mutex, ww_mutex_lock(s->lock, NULL))
>  
>  /*
>   * SEQCNT_LOCKNAME_ZERO - static initializer for seqcount_LOCKNAME_t
> @@ -304,8 +301,7 @@ SEQCOUNT_LOCKNAME(ww_mutex,     struct ww_mutex, true,     &s->lock->base, ww_mu
>  	__seqprop_case((s),	raw_spinlock,	prop),			\
>  	__seqprop_case((s),	spinlock,	prop),			\
>  	__seqprop_case((s),	rwlock,		prop),			\
> -	__seqprop_case((s),	mutex,		prop),			\
> -	__seqprop_case((s),	ww_mutex,	prop))
> +	__seqprop_case((s),	mutex,		prop))
>  
>  #define seqprop_ptr(s)			__seqprop(s, ptr)
>  #define seqprop_sequence(s)		__seqprop(s, sequence)
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch