/* * linux/kernel/irq/autoprobe.c * * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar * * This file contains the interrupt probing code and driver APIs. */ #include #include #include #include #include #include "internals.h" /* * Autodetection depends on the fact that any interrupt that * comes in on to an unassigned handler will get stuck with * "IRQS_WAITING" cleared and the interrupt disabled. */ static DEFINE_MUTEX(probing_active); /** * probe_irq_on - begin an interrupt autodetect * * Commence probing for an interrupt. The interrupts are scanned * and a mask of potential interrupt lines is returned. * */ unsigned long probe_irq_on(void) { struct irq_desc *desc; unsigned long mask = 0; int i; /* * quiesce the kernel, or at least the asynchronous portion */ async_synchronize_full(); mutex_lock(&probing_active); /* * something may have generated an irq long ago and we want to * flush such a longstanding irq before considering it as spurious. */ for_each_irq_desc_reverse(i, desc) { raw_spin_lock_irq(&desc->lock); if (!desc->action && irq_settings_can_probe(desc)) { /* * Some chips need to know about probing in * progress: */ if (desc->irq_data.chip->irq_set_type) desc->irq_data.chip->irq_set_type(&desc->irq_data, IRQ_TYPE_PROBE); irq_startup(desc, false); } raw_spin_unlock_irq(&desc->lock); } /* Wait for longstanding interrupts to trigger. */ msleep(20); /* * enable any unassigned irqs * (we must startup again here because if a longstanding irq * happened in the previous stage, it may have masked itself) */ for_each_irq_desc_reverse(i, desc) { raw_spin_lock_irq(&desc->lock); if (!desc->action && irq_settings_can_probe(desc)) { desc->istate |= IRQS_AUTODETECT | IRQS_WAITING; if (irq_startup(desc, false)) desc->istate |= IRQS_PENDING; } raw_spin_unlock_irq(&desc->lock); } /* * Wait for spurious interrupts to trigger */ msleep(100); /* * Now filter out any obviously spurious interrupts */ for_each_irq_desc(i, desc) { raw_spin_lock_irq(&desc->lock); if (desc->istate & IRQS_AUTODETECT) { /* It triggered already - consider it spurious. */ if (!(desc->istate & IRQS_WAITING)) { desc->istate &= ~IRQS_AUTODETECT; irq_shutdown(desc); } else if (i < 32) mask |= 1 << i; } raw_spin_unlock_irq(&desc->lock); } return mask; } EXPORT_SYMBOL(probe_irq_on); /** * probe_irq_mask - scan a bitmap of interrupt lines * @val: mask of interrupts to consider * * Scan the interrupt lines and return a bitmap of active * autodetect interrupts. The interrupt probe logic state * is then returned to its previous value. * * Note: we need to scan all the irq's even though we will * only return autodetect irq numbers - just so that we reset * them all to a known state. */ unsigned int probe_irq_mask(unsigned long val) { unsigned int mask = 0; struct irq_desc *desc; int i; for_each_irq_desc(i, desc) { raw_spin_lock_irq(&desc->lock); if (desc->istate & IRQS_AUTODETECT) { if (i < 16 && !(desc->istate & IRQS_WAITING)) mask |= 1 << i; desc->istate &= ~IRQS_AUTODETECT; irq_shutdown(desc); } raw_spin_unlock_irq(&desc->lock); } mutex_unlock(&probing_active); return mask & val; } EXPORT_SYMBOL(probe_irq_mask); /** * probe_irq_off - end an interrupt autodetect * @val: mask of potential interrupts (unused) * * Scans the unused interrupt lines and returns the line which * appears to have triggered the interrupt. If no interrupt was * found then zero is returned. If more than one interrupt is * found then minus the first candidate is returned to indicate * their is doubt. * * The interrupt probe logic state is returned to its previous * value. * * BUGS: When used in a module (which arguably shouldn't happen) * nothing prevents two IRQ probe callers from overlapping. The * results of this are non-optimal. */ int probe_irq_off(unsigned long val) { int i, irq_found = 0, nr_of_irqs = 0; struct irq_desc *desc; for_each_irq_desc(i, desc) { raw_spin_lock_irq(&desc->lock); if (desc->istate & IRQS_AUTODETECT) { if (!(desc->istate & IRQS_WAITING)) { if (!nr_of_irqs) irq_found = i; nr_of_irqs++; } desc->istate &= ~IRQS_AUTODETECT; irq_shutdown(desc); } raw_spin_unlock_irq(&desc->lock); } mutex_unlock(&probing_active); if (nr_of_irqs > 1) irq_found = -irq_found; return irq_found; } EXPORT_SYMBOL(probe_irq_off); '>mode:
authorSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-30 19:27:10 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-31 09:13:49 -0500
commit79c6f448c8b79c321e4a1f31f98194e4f6b6cae7 (patch)
tree370efda701f03cccf21e02bb1fdd3b852547d75c /include/uapi/video/sisfb.h
parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
tracing: Fix hwlat kthread migration
The hwlat tracer creates a kernel thread at start of the tracer. It is pinned to a single CPU and will move to the next CPU after each period of running. If the user modifies the migration thread's affinity, it will not change after that happens. The original code created the thread at the first instance it was called, but later was changed to destroy the thread after the tracer was finished, and would not be created until the next instance of the tracer was established. The code that initialized the affinity was only called on the initial instantiation of the tracer. After that, it was not initialized, and the previous affinity did not match the current newly created one, making it appear that the user modified the thread's affinity when it did not, and the thread failed to migrate again. Cc: stable@vger.kernel.org Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'include/uapi/video/sisfb.h')