user/sven/linux.git/kernel/rcu, branch v6.13.7

Merge tag 'irq-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-11-19T23:54:19Z

Pull interrupt subsystem updates from Thomas Gleixner: "Tree wide: - Make nr_irqs static to the core code and provide accessor functions to remove existing and prevent future aliasing problems with local variables or function arguments of the same name. Core code: - Prevent freeing an interrupt in the devres code which is not managed by devres in the first place. - Use seq_put_decimal_ull_width() for decimal values output in /proc/interrupts which increases performance significantly as it avoids parsing the format strings over and over. - Optimize raising the timer and hrtimer soft interrupts by using the 'set bit only' variants instead of the combined version which checks whether ksoftirqd should be woken up. The latter is a pointless exercise as both soft interrupts are raised in the context of the timer interrupt and therefore never wake up ksoftirqd. - Delegate timer/hrtimer soft interrupt processing to a dedicated thread on RT. Timer and hrtimer soft interrupts are always processed in ksoftirqd on RT enabled kernels. This can lead to high latencies when other soft interrupts are delegated to ksoftirqd as well. The separate thread allows to run them seperately under a RT scheduling policy to reduce the latency overhead. Drivers: - New drivers or extensions of existing drivers to support Renesas RZ/V2H(P), Aspeed AST27XX, T-HEAD C900 and ATMEL sam9x7 interrupt chips - Support for multi-cluster GICs on MIPS. MIPS CPUs can come with multiple CPU clusters, where each CPU cluster has its own GIC (Generic Interrupt Controller). This requires to access the GIC of a remote cluster through a redirect register block. This is encapsulated into a set of helper functions to keep the complexity out of the actual code paths which handle the GIC details. - Support for encrypted guests in the ARM GICV3 ITS driver The ITS page needs to be shared with the hypervisor and therefore must be decrypted. - Small cleanups and fixes all over the place" * tag 'irq-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits) irqchip/riscv-aplic: Prevent crash when MSI domain is missing genirq/proc: Use seq_put_decimal_ull_width() for decimal values softirq: Use a dedicated thread for timer wakeups on PREEMPT_RT. timers: Use __raise_softirq_irqoff() to raise the softirq. hrtimer: Use __raise_softirq_irqoff() to raise the softirq riscv: defconfig: Enable T-HEAD C900 ACLINT SSWI drivers irqchip: Add T-HEAD C900 ACLINT SSWI driver dt-bindings: interrupt-controller: Add T-HEAD C900 ACLINT SSWI device irqchip/stm32mp-exti: Use of_property_present() for non-boolean properties irqchip/mips-gic: Fix selection of GENERIC_IRQ_EFFECTIVE_AFF_MASK irqchip/mips-gic: Prevent indirect access to clusters without CPU cores irqchip/mips-gic: Multi-cluster support irqchip/mips-gic: Setup defaults in each cluster irqchip/mips-gic: Support multi-cluster in for_each_online_cpu_gic() irqchip/mips-gic: Replace open coded online CPU iterations genirq/irqdesc: Use str_enabled_disabled() helper in wakeup_show() genirq/devres: Don't free interrupt which is not managed by devres irqchip/gic-v3-its: Fix over allocation in itt_alloc_pool() irqchip/aspeed-intc: Add AST27XX INTC support dt-bindings: interrupt-controller: Add support for ASPEED AST27XX INTC ...

Merge tag 'rcu.release.v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

2024-11-19T19:27:07Z

Pull RCU updates from Frederic Weisbecker: "SRCU: - Introduction of the new SRCU-lite flavour with a new pair of srcu_read_[un]lock_lite() APIs. In practice the read side using this flavour becomes lighter by removing a full memory barrier on LOCK and a full memory barrier on UNLOCK. This comes at the expense of a higher latency write side with two (in the best case of a snaphot of unused read-sides) or more RCU grace periods on the update side which now assumes by itself the whole full ordering guarantee against the LOCK/UNLOCK counters on both indexes, along with the accesses performed inside. Uretprobes is a known potential user. Note this doesn't replace the default normal flavour of SRCU which still behaves the same as usual. - Add testing of SRCU-lite through rcutorture and rcuscale - Various cleanups on the way. Fixes: - Allow short-circuiting RCU-TASKS-RUDE grace periods on architectures that have sane noinstr boundaries forbidding tracing on low-level idle and kernel entry code. RCU-TASKS is enough on such configurations because it involves an RCU grace period that waits for all idle tasks to either schedule out voluntarily or enter into RCU unwatched noinstr code. - Allow and test start_poll_synchronize_rcu() with IRQs disabled. - Mention rcuog kthreads in relevant documentation and Kconfig help - Various fixes and consolidations rcutorture: - Add --no-affinity on tools to leave the affinity setting of guests up to the user. - Add guest_os_delay parameter to rcuscale for better warm-up control. - Fix and improve some rcuscale error handling. - Various cleanups and fixes stall: - Remove dead code - Stop dumping tasks if a stalled grace period eventually ended midway as that only produces confusing output. - Optimize detection of stalling CPUs and avoid useless node locking otherwise. NOCB: - Fix rcu_barrier() hang due to a race against callbacks deoffloading. This is not yet used, except by rcutorture, and waits for its promised cpusets interface. - Remove leftover function declaration" * tag 'rcu.release.v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (42 commits) rcuscale: Remove redundant WARN_ON_ONCE() splat rcuscale: Do a proper cleanup if kfree_scale_init() fails srcu: Unconditionally record srcu_read_lock_lite() in ->srcu_reader_flavor srcu: Check for srcu_read_lock_lite() across all CPUs srcu: Remove smp_mb() from srcu_read_unlock_lite() rcutorture: Avoid printing cpu=-1 for no-fault RCU boost failure rcuscale: Add guest_os_delay module parameter refscale: Correct affinity check torture: Add --no-affinity parameter to kvm.sh rcu/nocb: Fix missed RCU barrier on deoffloading rcu/kvfree: Fix data-race in __mod_timer / kvfree_call_rcu rcu/srcutiny: don't return before reenabling preemption rcu-tasks: Remove open-coded one-byte cmpxchg() emulation doc: Remove kernel-parameters.txt entry for rcutorture.read_exit rcutorture: Test start-poll primitives with interrupts disabled rcu: Permit start_poll_synchronize_rcu*() with interrupts disabled rcu: Allow short-circuiting of synchronize_rcu_tasks_rude() doc: Add rcuog kthreads to kernel-per-CPU-kthreads.rst rcu: Add rcuog kthreads to RCU_NOCB_CPU help text rcu: Use the BITS_PER_LONG macro ...

Merge branches 'rcu/fixes', 'rcu/nocb', 'rcu/torture', 'rcu/stall' and 'rcu/srcu' into rcu/dev

2024-11-15T21:38:53Z

rcuscale: Remove redundant WARN_ON_ONCE() splat

2024-11-15T21:24:41Z

There are two places where WARN_ON_ONCE() is called two times in the error paths. One which is encapsulated into if() condition and another one, which is unnecessary, is placed in the brackets. Remove an extra WARN_ON_ONCE() splat which is in brackets. Reviewed-by: Paul E. McKenney Reviewed-by: Neeraj Upadhyay Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Frederic Weisbecker

rcuscale: Do a proper cleanup if kfree_scale_init() fails

2024-11-15T21:23:50Z

A static analyzer for C, Smatch, reports and triggers below warnings: kernel/rcu/rcuscale.c:1215 rcu_scale_init() warn: inconsistent returns 'global &fullstop_mutex'. The checker complains about, we do not unlock the "fullstop_mutex" mutex, in case of hitting below error path: ... if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) { pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n"); WARN_ON_ONCE(1); return -1; ^^^^^^^^^^ ... it happens because "-1" is returned right away instead of doing a proper unwinding. Fix it by jumping to "unwind" label instead of returning -1. Reported-by: Dan Carpenter Reviewed-by: Paul E. McKenney Reviewed-by: Neeraj Upadhyay Closes: https://lore.kernel.org/rcu/ZxfTrHuEGtgnOYWp@pc636/T/ Fixes: 084e04fff160 ("rcuscale: Add laziness and kfree tests") Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Frederic Weisbecker

srcu: Unconditionally record srcu_read_lock_lite() in ->srcu_reader_flavor

2024-11-15T21:13:37Z

Currently, srcu_read_lock_lite() uses the SRCU_READ_FLAVOR_LITE bit in ->srcu_reader_flavor to communicate to the grace-period processing in srcu_readers_active_idx_check() that the smp_mb() must be replaced by a synchronize_rcu(). Unfortunately, ->srcu_reader_flavor is not updated unless the kernel is built with CONFIG_PROVE_RCU=y. Therefore in all kernels built with CONFIG_PROVE_RCU=n, srcu_readers_active_idx_check() incorrectly uses smp_mb() instead of synchronize_rcu() for srcu_struct structures whose readers use srcu_read_lock_lite(). This commit therefore causes Tree SRCU srcu_read_lock_lite() to unconditionally update ->srcu_reader_flavor so that srcu_readers_active_idx_check() can make the correct choice. Reported-by: Neeraj Upadhyay Closes: https://lore.kernel.org/all/d07e8f4a-d5ff-4c8e-8e61-50db285c57e9@amd.com/ Fixes: c0f08d6b5a61 ("srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite()") Signed-off-by: Paul E. McKenney Cc: Frederic Weisbecker Reviewed-by: Neeraj Upadhyay Signed-off-by: Frederic Weisbecker

srcu: Check for srcu_read_lock_lite() across all CPUs

2024-11-12T22:31:28Z

If srcu_read_lock_lite() is used on a given srcu_struct structure, then the grace-period processing must do synchronize_rcu() instead of smp_mb() between the scans of the ->srcu_unlock_count[] and ->srcu_lock_count[] counters. Currently, it does that by testing the SRCU_READ_FLAVOR_LITE bit of the ->srcu_reader_flavor mask, which works well. But only if the CPU running that srcu_struct structure's grace period has previously executed srcu_read_lock_lite(), which might not be the case, especially just after that srcu_struct structure has been created and initialized. This commit therefore updates the srcu_readers_unlock_idx() function to OR together the ->srcu_reader_flavor masks from all CPUs, and then make the srcu_readers_active_idx_check() function that test the SRCU_READ_FLAVOR_LITE bit in the resulting mask. Note that the srcu_readers_unlock_idx() function is already scanning all the CPUs to sum up the ->srcu_unlock_count[] fields and that this is on the grace-period slow path, hence no concerns about the small amount of extra work. Reported-by: Neeraj Upadhyay Closes: https://lore.kernel.org/all/d07e8f4a-d5ff-4c8e-8e61-50db285c57e9@amd.com/ Fixes: c0f08d6b5a61 ("srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite()") Signed-off-by: Paul E. McKenney Cc: Frederic Weisbecker Reviewed-by: Neeraj Upadhyay Signed-off-by: Frederic Weisbecker

rcutorture: Avoid printing cpu=-1 for no-fault RCU boost failure

2024-11-12T22:05:11Z

If a CPU runs throughout the stalled grace period without passing through a quiescent state, RCU priority boosting cannot help. The rcu_torture_boost_failed() function therefore prints a message flagging the first such CPU. However, if the stall was instead due to (for example) RCU's grace-period kthread being starved of CPU, there will be no such CPU, causing rcu_check_boost_fail() to instead pass back -1 through its cpup CPU-pointer parameter. Therefore, the current message complains about a mythical CPU -1. This commit therefore checks for this situation, and notes that all CPUs have passed through a quiescent state. Signed-off-by: Paul E. McKenney Reviewed-by: Neeraj Upadhyay Signed-off-by: Frederic Weisbecker

rcuscale: Add guest_os_delay module parameter

2024-11-12T22:05:05Z

This commit adds a guest_os_delay module parameter that extends warm-up and cool-down the specified number of seconds before and after the series of test runs. This allows the data-collection intervals from any given rcuscale guest OSes to line up with active periods in the other rcuscale guest OSes, and also allows the thermal warm-up period required to obtain consistent results from one test to the next. Signed-off-by: Paul E. McKenney Reviewed-by: Neeraj Upadhyay Signed-off-by: Frederic Weisbecker

refscale: Correct affinity check

2024-11-12T22:04:50Z

The current affinity check works fine until there are more reader processes than CPUs, at which point the affinity check is looking for non-existent CPUs. This commit therefore applies the same modulus to the check as is present in the set_cpus_allowed_ptr() call. Signed-off-by: Paul E. McKenney Reviewed-by: Neeraj Upadhyay Signed-off-by: Frederic Weisbecker