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authorLinus Torvalds <torvalds@linux-foundation.org>2018-08-13 10:47:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-13 10:47:26 -0700
commitd0daaeaf60143c02a2ef87f9f0703b63a0a7f8b3 (patch)
tree37117a1589f55f3b103e71f6180c66b47c6bfdea /kernel/irq
parent400439275d9543286f9d3f2925c3156f888e6b18 (diff)
parent9e90c7985229430428dc9ba0ec7fe422901b456d (diff)
downloadlinux-d0daaeaf60143c02a2ef87f9f0703b63a0a7f8b3.tar.bz2
Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull genirq updates from Thomas Gleixner: "The irq departement provides: - A synchronization fix for free_irq() to synchronize just the removed interrupt thread on shared interrupt lines. - Consolidate the multi low level interrupt entry handling and mvoe it to the generic code instead of adding yet another copy for RISC-V - Refactoring of the ARM LPI allocator and LPI exposure to the hypervisor - Yet another interrupt chip driver for the JZ4725B SoC - Speed up for /proc/interrupts as people seem to love reading this file with high frequency - Miscellaneous fixes and updates" * 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits) irqchip/gic-v3-its: Make its_lock a raw_spin_lock_t genirq/irqchip: Remove MULTI_IRQ_HANDLER as it's now obselete openrisc: Use the new GENERIC_IRQ_MULTI_HANDLER arm64: Use the new GENERIC_IRQ_MULTI_HANDLER ARM: Convert to GENERIC_IRQ_MULTI_HANDLER irqchip: Port the ARM IRQ drivers to GENERIC_IRQ_MULTI_HANDLER irqchip/gic-v3-its: Reduce minimum LPI allocation to 1 for PCI devices dt-bindings: irqchip: renesas-irqc: Document r8a77980 support dt-bindings: irqchip: renesas-irqc: Document r8a77470 support irqchip/ingenic: Add support for the JZ4725B SoC irqchip/stm32: Add exti0 translation for stm32mp1 genirq: Remove redundant NULL pointer check in __free_irq() irqchip/gic-v3-its: Honor hypervisor enforced LPI range irqchip/gic-v3: Expose GICD_TYPER in the rdist structure irqchip/gic-v3-its: Drop chunk allocation compatibility irqchip/gic-v3-its: Move minimum LPI requirements to individual busses irqchip/gic-v3-its: Use full range of LPIs irqchip/gic-v3-its: Refactor LPI allocator genirq: Synchronize only with single thread on free_irq() genirq: Update code comments wrt recycled thread_mask ...
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/Kconfig1
-rw-r--r--kernel/irq/irqdesc.c13
-rw-r--r--kernel/irq/manage.c47
-rw-r--r--kernel/irq/proc.c22
4 files changed, 47 insertions, 36 deletions
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index c6766f326072..5f3e2baefca9 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -134,7 +134,6 @@ config GENERIC_IRQ_DEBUGFS
endmenu
config GENERIC_IRQ_MULTI_HANDLER
- depends on !MULTI_IRQ_HANDLER
bool
help
Allow to specify the low level IRQ handler at run time.
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index afc7f902d74a..578d0e5f1b5b 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -443,6 +443,7 @@ static void free_desc(unsigned int irq)
* We free the descriptor, masks and stat fields via RCU. That
* allows demultiplex interrupts to do rcu based management of
* the child interrupts.
+ * This also allows us to use rcu in kstat_irqs_usr().
*/
call_rcu(&desc->rcu, delayed_free_desc);
}
@@ -928,17 +929,17 @@ unsigned int kstat_irqs(unsigned int irq)
* kstat_irqs_usr - Get the statistics for an interrupt
* @irq: The interrupt number
*
- * Returns the sum of interrupt counts on all cpus since boot for
- * @irq. Contrary to kstat_irqs() this can be called from any
- * preemptible context. It's protected against concurrent removal of
- * an interrupt descriptor when sparse irqs are enabled.
+ * Returns the sum of interrupt counts on all cpus since boot for @irq.
+ * Contrary to kstat_irqs() this can be called from any context.
+ * It uses rcu since a concurrent removal of an interrupt descriptor is
+ * observing an rcu grace period before delayed_free_desc()/irq_kobj_release().
*/
unsigned int kstat_irqs_usr(unsigned int irq)
{
unsigned int sum;
- irq_lock_sparse();
+ rcu_read_lock();
sum = kstat_irqs(irq);
- irq_unlock_sparse();
+ rcu_read_unlock();
return sum;
}
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 9a8b7ba9aa88..fb86146037a7 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -790,9 +790,19 @@ static irqreturn_t irq_forced_secondary_handler(int irq, void *dev_id)
static int irq_wait_for_interrupt(struct irqaction *action)
{
- set_current_state(TASK_INTERRUPTIBLE);
+ for (;;) {
+ set_current_state(TASK_INTERRUPTIBLE);
- while (!kthread_should_stop()) {
+ if (kthread_should_stop()) {
+ /* may need to run one last time */
+ if (test_and_clear_bit(IRQTF_RUNTHREAD,
+ &action->thread_flags)) {
+ __set_current_state(TASK_RUNNING);
+ return 0;
+ }
+ __set_current_state(TASK_RUNNING);
+ return -1;
+ }
if (test_and_clear_bit(IRQTF_RUNTHREAD,
&action->thread_flags)) {
@@ -800,10 +810,7 @@ static int irq_wait_for_interrupt(struct irqaction *action)
return 0;
}
schedule();
- set_current_state(TASK_INTERRUPTIBLE);
}
- __set_current_state(TASK_RUNNING);
- return -1;
}
/*
@@ -1024,11 +1031,8 @@ static int irq_thread(void *data)
/*
* This is the regular exit path. __free_irq() is stopping the
* thread via kthread_stop() after calling
- * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
- * oneshot mask bit can be set. We cannot verify that as we
- * cannot touch the oneshot mask at this point anymore as
- * __setup_irq() might have given out currents thread_mask
- * again.
+ * synchronize_hardirq(). So neither IRQTF_RUNTHREAD nor the
+ * oneshot mask bit can be set.
*/
task_work_cancel(current, irq_thread_dtor);
return 0;
@@ -1251,8 +1255,10 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
/*
* Protects against a concurrent __free_irq() call which might wait
- * for synchronize_irq() to complete without holding the optional
- * chip bus lock and desc->lock.
+ * for synchronize_hardirq() to complete without holding the optional
+ * chip bus lock and desc->lock. Also protects against handing out
+ * a recycled oneshot thread_mask bit while it's still in use by
+ * its previous owner.
*/
mutex_lock(&desc->request_mutex);
@@ -1571,9 +1577,6 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
- if (!desc)
- return NULL;
-
mutex_lock(&desc->request_mutex);
chip_bus_lock(desc);
raw_spin_lock_irqsave(&desc->lock, flags);
@@ -1620,11 +1623,11 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
/*
* Drop bus_lock here so the changes which were done in the chip
* callbacks above are synced out to the irq chips which hang
- * behind a slow bus (I2C, SPI) before calling synchronize_irq().
+ * behind a slow bus (I2C, SPI) before calling synchronize_hardirq().
*
* Aside of that the bus_lock can also be taken from the threaded
* handler in irq_finalize_oneshot() which results in a deadlock
- * because synchronize_irq() would wait forever for the thread to
+ * because kthread_stop() would wait forever for the thread to
* complete, which is blocked on the bus lock.
*
* The still held desc->request_mutex() protects against a
@@ -1636,7 +1639,7 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
unregister_handler_proc(irq, action);
/* Make sure it's not being used on another CPU: */
- synchronize_irq(irq);
+ synchronize_hardirq(irq);
#ifdef CONFIG_DEBUG_SHIRQ
/*
@@ -1645,7 +1648,7 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
* is so by doing an extra call to the handler ....
*
* ( We do this after actually deregistering it, to make sure that a
- * 'real' IRQ doesn't run in * parallel with our fake. )
+ * 'real' IRQ doesn't run in parallel with our fake. )
*/
if (action->flags & IRQF_SHARED) {
local_irq_save(flags);
@@ -1654,6 +1657,12 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
}
#endif
+ /*
+ * The action has already been removed above, but the thread writes
+ * its oneshot mask bit when it completes. Though request_mutex is
+ * held across this which prevents __setup_irq() from handing out
+ * the same bit to a newly requested action.
+ */
if (action->thread) {
kthread_stop(action->thread);
put_task_struct(action->thread);
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 37eda10f5c36..da9addb8d655 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -475,22 +475,24 @@ int show_interrupts(struct seq_file *p, void *v)
seq_putc(p, '\n');
}
- irq_lock_sparse();
+ rcu_read_lock();
desc = irq_to_desc(i);
if (!desc)
goto outsparse;
- raw_spin_lock_irqsave(&desc->lock, flags);
- for_each_online_cpu(j)
- any_count |= kstat_irqs_cpu(i, j);
- action = desc->action;
- if ((!action || irq_desc_is_chained(desc)) && !any_count)
- goto out;
+ if (desc->kstat_irqs)
+ for_each_online_cpu(j)
+ any_count |= *per_cpu_ptr(desc->kstat_irqs, j);
+
+ if ((!desc->action || irq_desc_is_chained(desc)) && !any_count)
+ goto outsparse;
seq_printf(p, "%*d: ", prec, i);
for_each_online_cpu(j)
- seq_printf(p, "%10u ", kstat_irqs_cpu(i, j));
+ seq_printf(p, "%10u ", desc->kstat_irqs ?
+ *per_cpu_ptr(desc->kstat_irqs, j) : 0);
+ raw_spin_lock_irqsave(&desc->lock, flags);
if (desc->irq_data.chip) {
if (desc->irq_data.chip->irq_print_chip)
desc->irq_data.chip->irq_print_chip(&desc->irq_data, p);
@@ -511,6 +513,7 @@ int show_interrupts(struct seq_file *p, void *v)
if (desc->name)
seq_printf(p, "-%-8s", desc->name);
+ action = desc->action;
if (action) {
seq_printf(p, " %s", action->name);
while ((action = action->next) != NULL)
@@ -518,10 +521,9 @@ int show_interrupts(struct seq_file *p, void *v)
}
seq_putc(p, '\n');
-out:
raw_spin_unlock_irqrestore(&desc->lock, flags);
outsparse:
- irq_unlock_sparse();
+ rcu_read_unlock();
return 0;
}
#endif