kernel/linux.git/include/linux/rcupdate.h, branch linux-6.9.y

rcu: add a helper to report consolidated flavor QS

2024-03-21T04:05:42+00:00

When under heavy load, network processing can run CPU-bound for many tens of seconds. Even in preemptible kernels (non-RT kernel), this can block RCU Tasks grace periods, which can cause trace-event removal to take more than a minute, which is unacceptably long. This commit therefore creates a new helper function that passes through both RCU and RCU-Tasks quiescent states every 100 milliseconds. This hard-coded value suffices for current workloads. Suggested-by: Paul E. McKenney Reviewed-by: Jesper Dangaard Brouer Signed-off-by: Yan Zhai Reviewed-by: Paul E. McKenney Acked-by: Jesper Dangaard Brouer Link: https://lore.kernel.org/r/90431d46ee112d2b0af04dbfe936faaca11810a5.1710877680.git.yan@cloudflare.com Signed-off-by: Jakub Kicinski

rcu-tasks: Repair RCU Tasks Trace quiescence check

2024-02-14T16:02:08+00:00

The context-switch-time check for RCU Tasks Trace quiescence expects current->trc_reader_special.b.need_qs to be zero, and if so, updates it to TRC_NEED_QS_CHECKED. This is backwards, because if this value is zero, there is no RCU Tasks Trace grace period in flight, an thus no need for a quiescent state. Instead, when a grace period starts, this field is set to TRC_NEED_QS. This commit therefore changes the check from zero to TRC_NEED_QS. Reported-by: Steven Rostedt Signed-off-by: Paul E. McKenney Tested-by: Steven Rostedt (Google) Signed-off-by: Boqun Feng

Merge branches 'doc.2023.12.13a', 'torture.2023.11.23a', 'fixes.2023.12.13a', 'rcu-tasks.2023.12.12b' and 'srcu.2023.12.13a' into rcu-merge.2023.12.13a

2023-12-13T19:51:31+00:00

srcu: Use try-lock lockdep annotation for NMI-safe access.

2023-12-13T18:11:19+00:00

It is claimed that srcu_read_lock_nmisafe() NMI-safe. However it triggers a lockdep if used from NMI because lockdep expects a deadlock since nothing disables NMIs while the lock is acquired. This is because commit f0f44752f5f61 ("rcu: Annotate SRCU's update-side lockdep dependencies") annotates synchronize_srcu() as a write lock usage. This helps to detect a deadlocks such as srcu_read_lock(); synchronize_srcu(); srcu_read_unlock(); The side effect is that the lock srcu_struct now has a USED usage in normal contexts, so it conflicts with a USED_READ usage in NMI. But this shouldn't cause a real deadlock because the write lock usage from synchronize_srcu() is a fake one and only used for read/write deadlock detection. Use a try-lock annotation for srcu_read_lock_nmisafe() to avoid lockdep complains if used from NMI. Fixes: f0f44752f5f6 ("rcu: Annotate SRCU's update-side lockdep dependencies") Link: https://lore.kernel.org/r/20230927160231.XRCDDSK4@linutronix.de Reviewed-by: Boqun Feng Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Paul E. McKenney Signed-off-by: Neeraj Upadhyay (AMD)

rcu: Remove unused macros from rcupdate.h

2023-12-11T21:02:03+00:00

ulong2long, USHORT_CMP_GE and USHORT_CMP_LT are redundant and have been unused for quite a few releases. Signed-off-by: Pedro Falcato Signed-off-by: Paul E. McKenney Signed-off-by: Neeraj Upadhyay (AMD)

rcu: Standardize explicit CPU-hotplug calls

2023-10-04T20:29:45+00:00

rcu_report_dead() and rcutree_migrate_callbacks() have their headers in rcupdate.h while those are pure rcutree calls, like the other CPU-hotplug functions. Also rcu_cpu_starting() and rcu_report_dead() have different naming conventions while they mirror each other's effects. Fix the headers and propose a naming that relates both functions and aligns with the prefix of other rcutree CPU-hotplug functions. Reviewed-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker

rcu: Assume rcu_report_dead() is always called locally

2023-10-04T15:35:56+00:00

rcu_report_dead() has to be called locally by the CPU that is going to exit the RCU state machine. Passing a cpu argument here is error-prone and leaves the possibility for a racy remote call. Use local access instead. Reviewed-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker

Merge tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue

2023-07-04T20:50:38+00:00

Pull scope-based resource management infrastructure from Peter Zijlstra: "These are the first few patches in the Scope-based Resource Management series that introduce the infrastructure but not any conversions as of yet. Adding the infrastructure now allows multiple people to start using them. Of note is that Sparse will need some work since it doesn't yet understand this attribute and might have decl-after-stmt issues" * tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue: kbuild: Drop -Wdeclaration-after-statement locking: Introduce __cleanup() based infrastructure apparmor: Free up __cleanup() name dmaengine: ioat: Free up __cleanup() name

locking: Introduce __cleanup() based infrastructure

2023-06-26T09:14:18+00:00

Use __attribute__((__cleanup__(func))) to build: - simple auto-release pointers using __free() - 'classes' with constructor and destructor semantics for scope-based resource management. - lock guards based on the above classes. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230612093537.614161713%40infradead.org

Merge branches 'doc.2023.05.10a', 'fixes.2023.05.11a', 'kvfree.2023.05.10a', 'nocb.2023.05.11a', 'rcu-tasks.2023.05.10a', 'torture.2023.05.15a' and 'rcu-urgent.2023.06.06a' into HEAD

2023-06-07T20:44:06+00:00

doc.2023.05.10a: Documentation updates fixes.2023.05.11a: Miscellaneous fixes kvfree.2023.05.10a: kvfree_rcu updates nocb.2023.05.11a: Callback-offloading updates rcu-tasks.2023.05.10a: Tasks RCU updates torture.2023.05.15a: Torture-test updates rcu-urgent.2023.06.06a: Urgent SRCU fix