Re: [PATCH 1/2 v4] cleanup: Add cond_guard() to conditional guards

Ira Weiny
2024-02-08T16:22:42Z

Jonathan Cameron wrote:
> On Thu, 8 Feb 2024 14:04:23 +0100
> "Fabio M. De Francesco" <fabio.maria.de.francesco@linux.intel.com> wrote:
>
> > Add cond_guard() macro to conditional guards.
> >
> > cond_guard() is a guard to be used with the conditional variants of locks,
> > like down_read_trylock() or mutex_lock_interruptible().
> >
> > It takes a statement (or statement-expression) that is passed as its
> > second argument. That statement (or statement-expression) is executed if
> > waiting for a lock is interrupted or if a _trylock() fails in case of
> > contention.
> >
> > Usage example:
> >
> > cond_guard(mutex_intr, return -EINTR, &mutex);
> >
> > Consistent with other usage of _guard(), locks are unlocked at the exit of the
> > scope where cond_guard() is called.
> >
> > Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> I like the defensive else {}

Agreed.

Re-

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>
>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Suggested-by: Dan Williams <dan.j.williams@intel.com>
> > Suggested-by: Ira Weiny <ira.weiny@intel.com>
> > Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> > Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> > Signed-off-by: Fabio M. De Francesco <fabio.maria.de.francesco@linux.intel.com>
> > ---
> > include/linux/cleanup.h | 15 +++++++++++++++
> > 1 file changed, 15 insertions(+)
> >
> > diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
> > index c2d09bc4f976..7b54ee996414 100644
> > --- a/include/linux/cleanup.h
> > +++ b/include/linux/cleanup.h
> > @@ -134,6 +134,16 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
> > * an anonymous instance of the (guard) class, not recommended for
> > * conditional locks.
> > *
> > + * cond_guard(name, fail, args...):
> > + * a guard to be used with the conditional variants of locks, like
> > + * down_read_trylock() or mutex_lock_interruptible. 'fail' is a
> > + * statement or statement-expression that is executed if waiting for a
> > + * lock is interrupted or if a _trylock() fails in case of contention.
> > + *
> > + * Example:
> > + *
> > + * cond_guard(mutex_intr, return -EINTR, &mutex);
> > + *
> > * scoped_guard (name, args...) { }:
> > * similar to CLASS(name, scope)(args), except the variable (with the
> > * explicit name 'scope') is declard in a for-loop such that its scope is
> > @@ -165,6 +175,11 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
> >
> > #define __guard_ptr(_name) class_##_name##_lock_ptr
> >
> > +#define cond_guard(_name, _fail, args...) \
> > + CLASS(_name, scope)(args); \
> > + if (!__guard_ptr(_name)(&scope)) _fail; \
> > + else { }
> > +
> > #define scoped_guard(_name, args...) \
> > for (CLASS(_name, scope)(args), \
> > *done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
>
>