linux-toradex.git/include/linux/srcutiny.h, branch v6.6-rc5

srcu,notifier: Remove #ifdefs in favor of SRCU Tiny srcu_usage

2023-08-16T21:27:01+00:00

This commit removes two #ifdef directives from include/linux/notifier.h
by causing SRCU Tiny to provide a dummy srcu_usage structure and a dummy
__SRCU_USAGE_INIT() macro.

Suggested-by: Linus Torvalds 
Cc: Matthias Brugger 
Cc: "Rafael J. Wysocki" 
Cc: "Michał Mirosław" 
Cc: Dmitry Osipenko 
Cc: Sachin Sant 
Cc: Joel Fernandes (Google) 
Signed-off-by: Paul E. McKenney

srcu: Begin offloading srcu_struct fields to srcu_update

2023-04-04T15:35:34+00:00

The current srcu_struct structure is on the order of 200 bytes in size
(depending on architecture and .config), which is much better than the
old-style 26K bytes, but still all too inconvenient when one is trying
to achieve good cache locality on a fastpath involving SRCU readers.

However, only a few fields in srcu_struct are used by SRCU readers.
The remaining fields could be offloaded to a new srcu_update
structure, thus shrinking the srcu_struct structure down to a few
tens of bytes.  This commit begins this noble quest, a quest that is
complicated by open-coded initialization of the srcu_struct within the
srcu_notifier_head structure.  This complication is addressed by updating
the srcu_notifier_head structure's open coding, given that there does
not appear to be a straightforward way of abstracting that initialization.

This commit moves only the ->node pointer to srcu_update.  Later commits
will move additional fields.

[ paulmck: Fold in qiang1.zhang@intel.com's memory-leak fix. ]

Link: https://lore.kernel.org/all/20230320055751.4120251-1-qiang1.zhang@intel.com/
Suggested-by: Christoph Hellwig 
Cc: "Rafael J. Wysocki" 
Cc: "Michał Mirosław" 
Cc: Dmitry Osipenko 
Tested-by: Sachin Sant 
Tested-by: "Zhang, Qiang1" 
Acked-by: Rafael J. Wysocki 
Tested-by: Joel Fernandes (Google) 
Signed-off-by: Paul E. McKenney

srcu: Make Tiny SRCU use full-sized grace-period counters

2022-08-31T12:10:15+00:00

This commit makes Tiny SRCU use full-sized grace-period counters to
further avoid counter-wrap issues when using polled grace-period APIs.

Signed-off-by: Paul E. McKenney

srcu: Add GP and maximum requested GP to Tiny SRCU rcutorture output

2022-08-31T12:10:15+00:00

This commit adds the ->srcu_idx and ->srcu_max_idx fields to the Tiny
SRCU rcutorture output for additional diagnostics.

Signed-off-by: Paul E. McKenney

srcutiny: Mark read-side data races

2021-08-06T20:41:48+00:00

This commit marks some interrupt-induced read-side data races in
__srcu_read_lock(), __srcu_read_unlock(), and srcu_torture_stats_print().

Signed-off-by: Paul E. McKenney

srcu: Provide polling interfaces for Tiny SRCU grace periods

2021-01-04T21:53:38+00:00

There is a need for a polling interface for SRCU grace
periods, so this commit supplies get_state_synchronize_srcu(),
start_poll_synchronize_srcu(), and poll_state_synchronize_srcu() for this
purpose.  The first can be used if future grace periods are inevitable
(perhaps due to a later call_srcu() invocation), the second if future
grace periods might not otherwise happen, and the third to check if a
grace period has elapsed since the corresponding call to either of the
first two.

As with get_state_synchronize_rcu() and cond_synchronize_rcu(),
the return value from either get_state_synchronize_srcu() or
start_poll_synchronize_srcu() must be passed in to a later call to
poll_state_synchronize_srcu().

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet 
[ paulmck: Add EXPORT_SYMBOL_GPL() per kernel test robot feedback. ]
[ paulmck: Apply feedback from Neeraj Upadhyay. ]
Link: https://lore.kernel.org/lkml/20201117004017.GA7444@paulmck-ThinkPad-P72/
Reviewed-by: Neeraj Upadhyay 
Signed-off-by: Paul E. McKenney

srcu: Make Tiny SRCU use multi-bit grace-period counter

2021-01-04T21:53:36+00:00

There is a need for a polling interface for SRCU grace periods.  This
polling needs to distinguish between an SRCU instance being idle on the
one hand or in the middle of a grace period on the other.  This commit
therefore converts the Tiny SRCU srcu_struct structure's srcu_idx from
a defacto boolean to a free-running counter, using the bottom bit to
indicate that a grace period is in progress.  The second-from-bottom
bit is thus used as the index returned by srcu_read_lock().

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet 
[ paulmck: Fix ->srcu_lock_nesting[] indexing per Neeraj Upadhyay. ]
Reviewed-by: Neeraj Upadhyay 
Signed-off-by: Paul E. McKenney

linux/srcu: Convert to SPDX license identifier

2019-02-09T16:45:59+00:00

Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.

Signed-off-by: Paul E. McKenney 
[ paulmck: Update ,h SPDX format per Joe Perches. ]
Reviewed-by: Thomas Gleixner

srcu: Use "ssp" instead of "sp" for srcu_struct pointer

2018-11-27T17:24:17+00:00

In RCU, the distinction between "rsp", "rnp", and "rdp" has served well
for a great many years, but in SRCU, "sp" vs. "sdp" has proven confusing.
This commit therefore renames SRCU's "sp" pointers to "ssp", so that there
is "ssp" for srcu_struct pointer, "snp" for srcu_node pointer, and "sdp"
for srcu_data pointer.

Signed-off-by: Paul E. McKenney

kernel/SRCU: provide a static initializer

2018-05-30T08:11:34+00:00

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.

Signed-off-by: Sebastian Andrzej Siewior 
Tested-by: Paul E. McKenney 
Reviewed-by: Paul E. McKenney 
Signed-off-by: Rafael J. Wysocki