Commit bc06a9e0 authored by Shanker Donthineni's avatar Shanker Donthineni Committed by Thomas Gleixner
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genirq: Use hlist for managing resend handlers 



The current implementation utilizes a bitmap for managing interrupt resend
handlers, which is allocated based on the SPARSE_IRQ/NR_IRQS macros.
However, this method may not efficiently utilize memory during runtime,
particularly when IRQ_BITMAP_BITS is large.

Address this issue by using an hlist to manage interrupt resend handlers
instead of relying on a static bitmap memory allocation. Additionally, a
new function, clear_irq_resend(), is introduced and called from
irq_shutdown to ensure a graceful teardown of the interrupt.

Signed-off-by: default avatarShanker Donthineni <sdonthineni@nvidia.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230519134902.1495562-2-sdonthineni@nvidia.com
parent d15121be

include/linux/irqdesc.h

+3 −0
Original line number Diff line number Diff line
@@ -102,6 +102,9 @@ struct irq_desc { 
	int			parent_irq;

	struct module		*owner;

	const char		*name;

#ifdef CONFIG_HARDIRQS_SW_RESEND

	struct hlist_node	resend_node;

#endif

} ____cacheline_internodealigned_in_smp;



#ifdef CONFIG_SPARSE_IRQ

kernel/irq/chip.c

+1 −0
Original line number Diff line number Diff line
@@ -306,6 +306,7 @@ static void __irq_disable(struct irq_desc *desc, bool mask); 
void irq_shutdown(struct irq_desc *desc)

{

	if (irqd_is_started(&desc->irq_data)) {

		clear_irq_resend(desc);

		desc->depth = 1;

		if (desc->irq_data.chip->irq_shutdown) {

			desc->irq_data.chip->irq_shutdown(&desc->irq_data);

kernel/irq/internals.h

+2 −0
Original line number Diff line number Diff line
@@ -113,6 +113,8 @@ irqreturn_t handle_irq_event(struct irq_desc *desc); 


/* Resending of interrupts :*/

int check_irq_resend(struct irq_desc *desc, bool inject);

void clear_irq_resend(struct irq_desc *desc);

void irq_resend_init(struct irq_desc *desc);

bool irq_wait_for_poll(struct irq_desc *desc);

void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action);

kernel/irq/irqdesc.c

+2 −0
Original line number Diff line number Diff line
@@ -415,6 +415,7 @@ static struct irq_desc *alloc_desc(int irq, int node, unsigned int flags, 
	desc_set_defaults(irq, desc, node, affinity, owner);

	irqd_set(&desc->irq_data, flags);

	kobject_init(&desc->kobj, &irq_kobj_type);

	irq_resend_init(desc);



	return desc;
@@ -581,6 +582,7 @@ int __init early_irq_init(void) 
		mutex_init(&desc[i].request_mutex);

		init_waitqueue_head(&desc[i].wait_for_threads);

		desc_set_defaults(i, &desc[i], node, NULL, NULL);

		irq_resend_init(desc);

	}

	return arch_early_irq_init();

}

kernel/irq/resend.c

+30 −17
Original line number Diff line number Diff line
@@ -21,8 +21,9 @@ 


#ifdef CONFIG_HARDIRQS_SW_RESEND



/* Bitmap to handle software resend of interrupts: */

static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS);

/* hlist_head to handle software resend of interrupts: */

static HLIST_HEAD(irq_resend_list);

static DEFINE_RAW_SPINLOCK(irq_resend_lock);



/*

 * Run software resends of IRQ's
@@ -30,18 +31,17 @@ static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS); 
static void resend_irqs(struct tasklet_struct *unused)

{

	struct irq_desc *desc;

	int irq;



	while (!bitmap_empty(irqs_resend, nr_irqs)) {

		irq = find_first_bit(irqs_resend, nr_irqs);

		clear_bit(irq, irqs_resend);

		desc = irq_to_desc(irq);

		if (!desc)

			continue;

		local_irq_disable();

	raw_spin_lock_irq(&irq_resend_lock);

	while (!hlist_empty(&irq_resend_list)) {

		desc = hlist_entry(irq_resend_list.first, struct irq_desc,

				   resend_node);

		hlist_del_init(&desc->resend_node);

		raw_spin_unlock(&irq_resend_lock);

		desc->handle_irq(desc);

		local_irq_enable();

		raw_spin_lock(&irq_resend_lock);

	}

	raw_spin_unlock_irq(&irq_resend_lock);

}



/* Tasklet to handle resend: */
@@ -49,8 +49,6 @@ static DECLARE_TASKLET(resend_tasklet, resend_irqs); 


static int irq_sw_resend(struct irq_desc *desc)

{

	unsigned int irq = irq_desc_get_irq(desc);



	/*

	 * Validate whether this interrupt can be safely injected from

	 * non interrupt context
@@ -70,16 +68,31 @@ static int irq_sw_resend(struct irq_desc *desc) 
		 */

		if (!desc->parent_irq)

			return -EINVAL;

		irq = desc->parent_irq;

	}



	/* Set it pending and activate the softirq: */

	set_bit(irq, irqs_resend);

	/* Add to resend_list and activate the softirq: */

	raw_spin_lock(&irq_resend_lock);

	hlist_add_head(&desc->resend_node, &irq_resend_list);

	raw_spin_unlock(&irq_resend_lock);

	tasklet_schedule(&resend_tasklet);

	return 0;

}



void clear_irq_resend(struct irq_desc *desc)

{

	raw_spin_lock(&irq_resend_lock);

	hlist_del_init(&desc->resend_node);

	raw_spin_unlock(&irq_resend_lock);

}



void irq_resend_init(struct irq_desc *desc)

{

	INIT_HLIST_NODE(&desc->resend_node);

}

#else

void clear_irq_resend(struct irq_desc *desc) {}

void irq_resend_init(struct irq_desc *desc) {}



static int irq_sw_resend(struct irq_desc *desc)

{

	return -EINVAL;