starfive-tech/linux.git/lib, branch rt-linux-release

lockdep/selftests: Adapt ww-tests for PREEMPT_RT

2023-11-06T11:24:45+00:00

The ww-mutex selftest operates directly on ww_mutex::base and assumes its type is struct mutex. This isn't true on PREEMPT_RT which turns the mutex into a rtmutex. Add a ww_mutex_base_ abstraction which maps to the relevant mutex_ or rt_mutex_ function. Change the CONFIG_DEBUG_MUTEXES ifdef to DEBUG_WW_MUTEXES. The latter is true for the MUTEX and RTMUTEX implementation of WW-MUTEX. The assignment is required in order to pass the tests. Signed-off-by: Sebastian Andrzej Siewior

lockdep/selftests: Skip the softirq related tests on PREEMPT_RT

2023-11-06T11:24:45+00:00

The softirq context on PREEMPT_RT is different compared to !PREEMPT_RT. As such lockdep_softirq_enter() is a nop and the all the "softirq safe" tests fail on PREEMPT_RT because there is no difference. Skip the softirq context tests on PREEMPT_RT. Signed-off-by: Sebastian Andrzej Siewior

lockdep/selftests: Unbalanced migrate_disable() & rcu_read_lock()

2023-11-06T11:24:44+00:00

The tests with unbalanced lock() + unlock() operation leave a modified preemption counter behind which is then reset to its original value after the test. The spin_lock() function on PREEMPT_RT does not include a preempt_disable() statement but migrate_disable() and read_rcu_lock(). As a consequence both counter never get back to their original value and system explodes later after the selftest. In the double-unlock case on PREEMPT_RT, the migrate_disable() and RCU code will trigger which should be avoided. These counter should not be decremented below their initial value. Save both counters and bring them back to their original value after the test. In the double-unlock case, increment both counter in advance to they become balanced after the double unlock. Signed-off-by: Sebastian Andrzej Siewior

lockdep/selftests: Add rtmutex to the last column

2023-11-06T11:24:44+00:00

The last column contains the results for the rtmutex tests. Add it. Signed-off-by: Sebastian Andrzej Siewior

lockdep/selftests: Avoid using local_lock_{acquire|release}().

2023-11-06T11:24:44+00:00

The functions local_lock related functions local_lock_acquire() local_lock_release() are part of the internal implementation and should be avoided. Define the lock as DEFINE_PER_CPU so the normal local_lock() function can be used. Signed-off-by: Sebastian Andrzej Siewior

irq_poll: Use raise_softirq_irqoff() in cpu_dead notifier

2023-11-06T11:24:41+00:00

__raise_softirq_irqoff() adds a bit to the pending sofirq mask and this is it. The softirq won't be handled in a deterministic way but randomly when an interrupt fires and handles softirq in its irq_exit() routine or if something randomly checks and handles pending softirqs in the call chain before the CPU goes idle. Add a local_bh_disable/enable() around the IRQ-off section which will handle pending softirqs. Signed-off-by: Sebastian Andrzej Siewior Link: https://lkml.kernel.org/r/20210930103754.2128949-1-bigeasy@linutronix.de

mm/scatterlist: Replace the !preemptible warning in sg_miter_stop()

2023-11-06T11:24:39+00:00

sg_miter_stop() checks for disabled preemption before unmapping a page via kunmap_atomic(). The kernel doc mentions under context that preemption must be disabled if SG_MITER_ATOMIC is set. There is no active requirement for the caller to have preemption disabled before invoking sg_mitter_stop(). The sg_mitter_*() implementation itself has no such requirement. In fact, preemption is disabled by kmap_atomic() as part of sg_miter_next() and remains disabled as long as there is an active SG_MITER_ATOMIC mapping. This is a consequence of kmap_atomic() and not a requirement for sg_mitter_*() itself. The user chooses SG_MITER_ATOMIC because it uses the API in a context where blocking is not possible or blocking is possible but he chooses a lower weight mapping which is not available on all CPUs and so it might need less overhead to setup at a price that now preemption will be disabled. The kmap_atomic() implementation on PREEMPT_RT does not disable preemption. It simply disables CPU migration to ensure that the task remains on the same CPU while the caller remains preemptible. This in turn triggers the warning in sg_miter_stop() because preemption is allowed. The PREEMPT_RT and !PREEMPT_RT implementation of kmap_atomic() disable pagefaults as a requirement. It is sufficient to check for this instead of disabled preemption. Check for disabled pagefault handler in the SG_MITER_ATOMIC case. Remove the "preemption disabled" part from the kernel doc as the sg_milter*() implementation does not care. [bigeasy: commit description. ] Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20211015211409.cqopacv3pxdwn2ty@linutronix.de

printk: add pr_flush()

2023-11-06T11:24:38+00:00

Provide a function to allow waiting for console printers to catch up to the latest logged message. Use pr_flush() to give console printers a chance to finish in critical situations if no atomic console is available. For now pr_flush() is only used in the most common error paths: panic(), print_oops_end_marker(), report_bug(), kmsg_dump(). Signed-off-by: John Ogness Signed-off-by: Thomas Gleixner

printk: remove deferred printing

2023-11-06T11:24:37+00:00

Since printing occurs either atomically or from the printing kthread, there is no need for any deferring or tracking possible recursion paths. Remove all printk defer functions and context tracking. Signed-off-by: John Ogness Signed-off-by: Thomas Gleixner

printk: rename printk cpulock API and always disable interrupts

2023-11-06T11:24:37+00:00

The printk cpulock functions use local_irq_disable(). This means that hardware interrupts are also disabled on PREEMPT_RT. To make this clear, rename the functions to use the raw_ prefix: raw_printk_cpu_lock_irqsave(flags); raw_printk_cpu_unlock_irqrestore(flags); Also, these functions were a NOP for !CONFIG_SMP. But for !CONFIG_SMP they still need to disable hardware interrupts. So modify them appropriately for this. Signed-off-by: John Ogness Signed-off-by: Thomas Gleixner