kernel/linux.git/include/linux/srcutiny.h, branch v6.12.80

srcu: Make Tiny SRCU explicitly disable preemption

2024-04-15T09:29:48+00:00

Because Tiny SRCU is used only in kernels built with either CONFIG_PREEMPT_NONE=y or CONFIG_PREEMPT_VOLUNTARY=y, there has not been any need for TINY SRCU to explicitly disable preemption. However, the prospect of lazy preemption changes that, and the lazy-preemption patches do result in rcutorture runs finding both too-short grace periods and grace-period hangs for Tiny SRCU. This commit therefore adds the needed preempt_disable() and preempt_enable() calls to Tiny SRCU. Signed-off-by: Paul E. McKenney Cc: Ankur Arora Cc: Thomas Gleixner Signed-off-by: Uladzislau Rezki (Sony)

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