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    SubjectRe: [PATCH 3/5] seqlock: introduce seqprop_lock/unlock
    On Wed, Sep 13, 2023 at 05:50:00PM +0200, Oleg Nesterov wrote:
    > which can be used to take/release the corresponding lock.
    >
    > Thanks to the previous patch, it is trivial to pass 2 arguments to
    > the new __seqprop_##lockname##_lock/unlock "methods", plus we do not
    > loose the type info and thus the new seqprop's are "type safe".
    >
    > So for example
    >
    > void func(seqcount_rwlock_t *s, rwlock_t *l)
    > {
    > seqprop_lock(s, l);
    > }
    >
    > happily compiles, but this one
    >
    > void func(seqcount_rwlock_t *s, spinlock_t *l)
    > {
    > seqprop_lock(s, l);
    > }
    >
    > doesn't.
    >
    > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    > ---
    > include/linux/seqlock.h | 21 +++++++++++++++++++++
    > 1 file changed, 21 insertions(+)
    >
    > diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
    > index 41e36f8afad4..9831683a0102 100644
    > --- a/include/linux/seqlock.h
    > +++ b/include/linux/seqlock.h
    > @@ -241,6 +241,21 @@ static __always_inline void \
    > __seqprop_##lockname##_assert(const seqcount_##lockname##_t *s) \
    > { \
    > __SEQ_LOCK(lockdep_assert_held(s->lock)); \
    > +} \
    > + \
    > +static __always_inline void \
    > +__seqprop_##lockname##_lock(seqcount_##lockname##_t *s, \
    > + locktype *lock) \
    > +{ \
    > + __SEQ_LOCK(WARN_ON_ONCE(s->lock != lock)); \
    > + lockbase##_lock(lock); \
    > +} \
    > + \
    > +static __always_inline void \
    > +__seqprop_##lockname##_unlock(seqcount_##lockname##_t *s, \
    > + locktype *lock) \
    > +{ \
    > + lockbase##_unlock(lock); \
    > }

    Why are you creating a new method with an unused argument s ?

    >
    > /*
    > @@ -306,6 +321,12 @@ SEQCOUNT_LOCKNAME(mutex, struct mutex, true, mutex)
    > #define seqprop_preemptible(s) __seqprop(s, preemptible)(s)
    > #define seqprop_assert(s) __seqprop(s, assert)(s)
    >
    > +/* seqcount_t doesn't have these methods */
    > +static inline void __seqprop_lock (seqcount_t *s, void *l) { BUILD_BUG(); }
    > +static inline void __seqprop_unlock (seqcount_t *s, void *l) { BUILD_BUG(); }
    > +#define seqprop_lock(s, l) __seqprop(s, lock)(s, l)
    > +#define seqprop_unlock(s, l) __seqprop(s, unlock)(s, l)
    > +
    > /**
    > * __read_seqcount_begin() - begin a seqcount_t read section w/o barrier
    > * @s: Pointer to seqcount_t or any of the seqcount_LOCKNAME_t variants
    > --
    > 2.25.1.362.g51ebf55
    >

    --
    Rgrds, legion

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