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SubjectRe: [PATCH 1/2] kernel/SRCU: provide a static initializer
On Tue, May 29, 2018 at 10:09:51AM +0200, Rafael J. Wysocki wrote:
> On Fri, May 25, 2018 at 12:19 PM, Sebastian Andrzej Siewior
> <bigeasy@linutronix.de> wrote:
> > There are macros for static initializer for the three out of four
> > possible notifier types, that are:
> > ATOMIC_NOTIFIER_HEAD()
> > BLOCKING_NOTIFIER_HEAD()
> > RAW_NOTIFIER_HEAD()
> >
> > This patch provides a static initilizer for the forth type to make it
> > complete.
> >
> > Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> I cannot apply this without an ACK from Paul.

I have both queued, but if you would prefer to take them, then for the
SRCU piece:

Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Thanx, Paul

> > ---
> > include/linux/notifier.h | 34 +++++++++++++++++++++++++++++-----
> > include/linux/srcutiny.h | 6 +++---
> > include/linux/srcutree.h | 6 +++---
> > 3 files changed, 35 insertions(+), 11 deletions(-)
> >
> > diff --git a/include/linux/notifier.h b/include/linux/notifier.h
> > index 6d731110e0db..f35c7bf76143 100644
> > --- a/include/linux/notifier.h
> > +++ b/include/linux/notifier.h
> > @@ -43,9 +43,7 @@
> > * in srcu_notifier_call_chain(): no cache bounces and no memory barriers.
> > * As compensation, srcu_notifier_chain_unregister() is rather expensive.
> > * SRCU notifier chains should be used when the chain will be called very
> > - * often but notifier_blocks will seldom be removed. Also, SRCU notifier
> > - * chains are slightly more difficult to use because they require special
> > - * runtime initialization.
> > + * often but notifier_blocks will seldom be removed.
> > */
> >
> > struct notifier_block;
> > @@ -91,7 +89,7 @@ struct srcu_notifier_head {
> > (name)->head = NULL; \
> > } while (0)
> >
> > -/* srcu_notifier_heads must be initialized and cleaned up dynamically */
> > +/* srcu_notifier_heads must be cleaned up dynamically */
> > extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
> > #define srcu_cleanup_notifier_head(name) \
> > cleanup_srcu_struct(&(name)->srcu);
> > @@ -104,7 +102,13 @@ extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
> > .head = NULL }
> > #define RAW_NOTIFIER_INIT(name) { \
> > .head = NULL }
> > -/* srcu_notifier_heads cannot be initialized statically */
> > +
> > +#define SRCU_NOTIFIER_INIT(name, pcpu) \
> > + { \
> > + .mutex = __MUTEX_INITIALIZER(name.mutex), \
> > + .head = NULL, \
> > + .srcu = __SRCU_STRUCT_INIT(name.srcu, pcpu), \
> > + }
> >
> > #define ATOMIC_NOTIFIER_HEAD(name) \
> > struct atomic_notifier_head name = \
> > @@ -116,6 +120,26 @@ extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
> > struct raw_notifier_head name = \
> > RAW_NOTIFIER_INIT(name)
> >
> > +#ifdef CONFIG_TREE_SRCU
> > +#define _SRCU_NOTIFIER_HEAD(name, mod) \
> > + static DEFINE_PER_CPU(struct srcu_data, \
> > + name##_head_srcu_data); \
> > + mod struct srcu_notifier_head name = \
> > + SRCU_NOTIFIER_INIT(name, name##_head_srcu_data)
> > +
> > +#else
> > +#define _SRCU_NOTIFIER_HEAD(name, mod) \
> > + mod struct srcu_notifier_head name = \
> > + SRCU_NOTIFIER_INIT(name, name)
> > +
> > +#endif
> > +
> > +#define SRCU_NOTIFIER_HEAD(name) \
> > + _SRCU_NOTIFIER_HEAD(name, /* not static */)
> > +
> > +#define SRCU_NOTIFIER_HEAD_STATIC(name) \
> > + _SRCU_NOTIFIER_HEAD(name, static)
> > +
> > #ifdef __KERNEL__
> >
> > extern int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
> > diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
> > index 261471f407a5..f41d2fb09f87 100644
> > --- a/include/linux/srcutiny.h
> > +++ b/include/linux/srcutiny.h
> > @@ -43,7 +43,7 @@ struct srcu_struct {
> >
> > void srcu_drive_gp(struct work_struct *wp);
> >
> > -#define __SRCU_STRUCT_INIT(name) \
> > +#define __SRCU_STRUCT_INIT(name, __ignored) \
> > { \
> > .srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \
> > .srcu_cb_tail = &name.srcu_cb_head, \
> > @@ -56,9 +56,9 @@ void srcu_drive_gp(struct work_struct *wp);
> > * Tree SRCU, which needs some per-CPU data.
> > */
> > #define DEFINE_SRCU(name) \
> > - struct srcu_struct name = __SRCU_STRUCT_INIT(name)
> > + struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
> > #define DEFINE_STATIC_SRCU(name) \
> > - static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
> > + static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
> >
> > void synchronize_srcu(struct srcu_struct *sp);
> >
> > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
> > index 4eda108abee0..745d4ca4dd50 100644
> > --- a/include/linux/srcutree.h
> > +++ b/include/linux/srcutree.h
> > @@ -104,9 +104,9 @@ struct srcu_struct {
> > #define SRCU_STATE_SCAN1 1
> > #define SRCU_STATE_SCAN2 2
> >
> > -#define __SRCU_STRUCT_INIT(name) \
> > +#define __SRCU_STRUCT_INIT(name, pcpu_name) \
> > { \
> > - .sda = &name##_srcu_data, \
> > + .sda = &pcpu_name, \
> > .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
> > .srcu_gp_seq_needed = 0 - 1, \
> > __SRCU_DEP_MAP_INIT(name) \
> > @@ -133,7 +133,7 @@ struct srcu_struct {
> > */
> > #define __DEFINE_SRCU(name, is_static) \
> > static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);\
> > - is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
> > + is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name##_srcu_data)
> > #define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
> > #define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)
> >
> > --
> > 2.17.0
> >
>

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