user/sven/linux.git/include/linux/rcupdate.h, branch v5.9.14

rcu: Introduce single argument kvfree_rcu() interface

2020-06-29T18:59:26Z

Make kvfree_rcu() capable of freeing objects that will not embed an rcu_head within it. This saves storage overhead in such objects. Reclaiming headless objects this way requires only a single argument (pointer to the object). After this patch, there are two ways to use kvfree_rcu(): a) kvfree_rcu(ptr, rhf); struct X { struct rcu_head rhf; unsigned char data[100]; }; void *ptr = kvmalloc(sizeof(struct X), GFP_KERNEL); if (ptr) kvfree_rcu(ptr, rhf); b) kvfree_rcu(ptr); void *ptr = kvmalloc(some_bytes, GFP_KERNEL); if (ptr) kvfree_rcu(ptr); Note that the headless usage (example b) can only be used in a code that can sleep. This is enforced by the CONFIG_DEBUG_ATOMIC_SLEEP option. Co-developed-by: Joel Fernandes (Google) Reviewed-by: Joel Fernandes (Google) Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Paul E. McKenney

rcu: Introduce 2 arg kvfree_rcu() interface

2020-06-29T18:59:25Z

kvmalloc() can allocate two types of objects: SLAB backed and vmalloc backed. How it behaves depends on requested object's size and memory pressure. Add a kvfree_rcu() interface that can free memory allocated via kvmalloc(). It is a simple alias to kfree_rcu() which can now handle either type of object. struct test_kvfree_rcu { struct rcu_head rcu; unsigned char array[100]; }; struct test_kvfree_rcu *p; p = kvmalloc(10 * PAGE_SIZE); if (p) kvfree_rcu(p, rcu); Signed-off-by: Uladzislau Rezki (Sony) Co-developed-by: Joel Fernandes (Google) Reviewed-by: Joel Fernandes (Google) Signed-off-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney

rcu: Rename _kfree_callback/_kfree_rcu_offset/kfree_call_*

2020-06-29T18:59:25Z

The following changes are introduced: 1. Rename rcu_invoke_kfree_callback() to rcu_invoke_kvfree_callback(), as well as the associated trace events, so the rcu_kfree_callback(), becomes rcu_kvfree_callback(). The reason is to be aligned with kvfree() notation. 2. Rename __is_kfree_rcu_offset to __is_kvfree_rcu_offset. All RCU paths use kvfree() now instead of kfree(), thus rename it. 3. Rename kfree_call_rcu() to the kvfree_call_rcu(). The reason is, it is capable of freeing vmalloc() memory now. Do the same with __kfree_rcu() macro, it becomes __kvfree_rcu(), the goal is the same. Reviewed-by: Joel Fernandes (Google) Co-developed-by: Joel Fernandes (Google) Signed-off-by: Joel Fernandes (Google) Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Paul E. McKenney

rcu-tasks: Make RCU Tasks Trace make use of RCU scheduler hooks

2020-04-27T18:03:52Z

This commit makes the calls to rcu_tasks_qs() detect and report quiescent states for RCU tasks trace. If the task is in a quiescent state and if ->trc_reader_checked is not yet set, the task sets its own ->trc_reader_checked. This will cause the grace-period kthread to remove it from the holdout list if it still remains there. [ paulmck: Fix conditional compilation per kbuild test robot feedback. ] Signed-off-by: Paul E. McKenney

rcu-tasks: Add an RCU-tasks rude variant

2020-04-27T18:03:51Z

This commit adds a "rude" variant of RCU-tasks that has as quiescent states schedule(), cond_resched_tasks_rcu_qs(), userspace execution, and (in theory, anyway) cond_resched(). In other words, RCU-tasks rude readers are regions of code with preemption disabled, but excluding code early in the CPU-online sequence and late in the CPU-offline sequence. Updates make use of IPIs and force an IPI and a context switch on each online CPU. This variant is useful in some situations in tracing. Suggested-by: Steven Rostedt [ paulmck: Apply EXPORT_SYMBOL_GPL() feedback from Qiujun Huang. ] Signed-off-by: Paul E. McKenney [ paulmck: Apply review feedback from Steve Rostedt. ]

rcu-tasks: Refactor RCU-tasks to allow variants to be added

2020-04-27T18:03:51Z

This commit splits out generic processing from RCU-tasks-specific processing in order to allow additional flavors to be added. It also adds a def_bool TASKS_RCU_GENERIC to enable the common RCU-tasks infrastructure code. This is primarily, but not entirely, a code-movement commit. Signed-off-by: Paul E. McKenney

Merge branches 'doc.2019.12.10a', 'exp.2019.12.09a', 'fixes.2020.01.24a', 'kfree_rcu.2020.01.24a', 'list.2020.01.10a', 'preempt.2020.01.24a' and 'torture.2019.12.09a' into HEAD

2020-01-24T18:37:27Z

doc.2019.12.10a: Documentations updates exp.2019.12.09a: Expedited grace-period updates fixes.2020.01.24a: Miscellaneous fixes kfree_rcu.2020.01.24a: Batch kfree_rcu() work list.2020.01.10a: RCU-protected-list updates preempt.2020.01.24a: Preemptible RCU updates torture.2019.12.09a: Torture-test updates

rcu: Move rcu_{expedited,normal} definitions into rcupdate.h

2020-01-24T18:33:50Z

This commit moves the rcu_{expedited,normal} definitions from kernel/rcu/update.c to include/linux/rcupdate.h to make sure they are in sync, and also to avoid the following warning from sparse: kernel/ksysfs.c:150:5: warning: symbol 'rcu_expedited' was not declared. Should it be static? kernel/ksysfs.c:167:5: warning: symbol 'rcu_normal' was not declared. Should it be static? Signed-off-by: Ben Dooks Signed-off-by: Paul E. McKenney

rcu: Remove rcu_swap_protected()

2019-12-12T18:24:52Z

Now that the calls to rcu_swap_protected() have been replaced by rcu_replace_pointer(), this commit removes rcu_swap_protected(). Link: https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4gg6Hw@mail.gmail.com/ Reported-by: Linus Torvalds Signed-off-by: Paul E. McKenney Cc: Bart Van Assche Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Johannes Thumshirn Cc: Shane M Seymour Cc: Martin K. Petersen

rcu: Use CONFIG_PREEMPTION where appropriate

2019-12-09T20:37:51Z

The config option `CONFIG_PREEMPT' is used for the preemption model "Low-Latency Desktop". The config option `CONFIG_PREEMPTION' is enabled when kernel preemption is enabled which is true for the preemption model `CONFIG_PREEMPT' and `CONFIG_PREEMPT_RT'. Use `CONFIG_PREEMPTION' if it applies to both preemption models and not just to `CONFIG_PREEMPT'. Cc: "Paul E. McKenney" Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes Cc: Davidlohr Bueso Cc: rcu@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Paul E. McKenney