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Release 4.16 lib/irq_poll.c

Directory: lib
// SPDX-License-Identifier: GPL-2.0
/*
 * Functions related to interrupt-poll handling in the block layer. This
 * is similar to NAPI for network devices.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bio.h>
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <linux/irq_poll.h>
#include <linux/delay.h>


static unsigned int irq_poll_budget __read_mostly = 256;

static DEFINE_PER_CPU(struct list_head, blk_cpu_iopoll);

/**
 * irq_poll_sched - Schedule a run of the iopoll handler
 * @iop:      The parent iopoll structure
 *
 * Description:
 *     Add this irq_poll structure to the pending poll list and trigger the
 *     raise of the blk iopoll softirq.
 **/

void irq_poll_sched(struct irq_poll *iop) { unsigned long flags; if (test_bit(IRQ_POLL_F_DISABLE, &iop->state)) return; if (test_and_set_bit(IRQ_POLL_F_SCHED, &iop->state)) return; local_irq_save(flags); list_add_tail(&iop->list, this_cpu_ptr(&blk_cpu_iopoll)); __raise_softirq_irqoff(IRQ_POLL_SOFTIRQ); local_irq_restore(flags); }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe3855.07%125.00%
Christoph Hellwig2942.03%250.00%
Christoph Lameter22.90%125.00%
Total69100.00%4100.00%

EXPORT_SYMBOL(irq_poll_sched); /** * __irq_poll_complete - Mark this @iop as un-polled again * @iop: The parent iopoll structure * * Description: * See irq_poll_complete(). This function must be called with interrupts * disabled. **/
static void __irq_poll_complete(struct irq_poll *iop) { list_del(&iop->list); smp_mb__before_atomic(); clear_bit_unlock(IRQ_POLL_F_SCHED, &iop->state); }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe2784.38%125.00%
Christoph Hellwig412.50%250.00%
Peter Zijlstra13.12%125.00%
Total32100.00%4100.00%

/** * irq_poll_complete - Mark this @iop as un-polled again * @iop: The parent iopoll structure * * Description: * If a driver consumes less than the assigned budget in its run of the * iopoll handler, it'll end the polled mode by calling this function. The * iopoll handler will not be invoked again before irq_poll_sched() * is called. **/
void irq_poll_complete(struct irq_poll *iop) { unsigned long flags; local_irq_save(flags); __irq_poll_complete(iop); local_irq_restore(flags); }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe2482.76%133.33%
Christoph Hellwig310.34%133.33%
Fabian Frederick26.90%133.33%
Total29100.00%3100.00%

EXPORT_SYMBOL(irq_poll_complete);
static void __latent_entropy irq_poll_softirq(struct softirq_action *h) { struct list_head *list = this_cpu_ptr(&blk_cpu_iopoll); int rearm = 0, budget = irq_poll_budget; unsigned long start_time = jiffies; local_irq_disable(); while (!list_empty(list)) { struct irq_poll *iop; int work, weight; /* * If softirq window is exhausted then punt. */ if (budget <= 0 || time_after(jiffies, start_time)) { rearm = 1; break; } local_irq_enable(); /* Even though interrupts have been re-enabled, this * access is safe because interrupts can only add new * entries to the tail of this list, and only ->poll() * calls can remove this head entry from the list. */ iop = list_entry(list->next, struct irq_poll, list); weight = iop->weight; work = 0; if (test_bit(IRQ_POLL_F_SCHED, &iop->state)) work = iop->poll(iop, weight); budget -= work; local_irq_disable(); /* * Drivers must not modify the iopoll state, if they * consume their assigned weight (or more, some drivers can't * easily just stop processing, they have to complete an * entire mask of commands).In such cases this code * still "owns" the iopoll instance and therefore can * move the instance around on the list at-will. */ if (work >= weight) { if (test_bit(IRQ_POLL_F_DISABLE, &iop->state)) __irq_poll_complete(iop); else list_move_tail(&iop->list, list); } } if (rearm) __raise_softirq_irqoff(IRQ_POLL_SOFTIRQ); local_irq_enable(); }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe17391.53%342.86%
Christoph Hellwig136.88%228.57%
Christoph Lameter21.06%114.29%
Emese Revfy10.53%114.29%
Total189100.00%7100.00%

/** * irq_poll_disable - Disable iopoll on this @iop * @iop: The parent iopoll structure * * Description: * Disable io polling and wait for any pending callbacks to have completed. **/
void irq_poll_disable(struct irq_poll *iop) { set_bit(IRQ_POLL_F_DISABLE, &iop->state); while (test_and_set_bit(IRQ_POLL_F_SCHED, &iop->state)) msleep(1); clear_bit(IRQ_POLL_F_DISABLE, &iop->state); }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe4289.36%150.00%
Christoph Hellwig510.64%150.00%
Total47100.00%2100.00%

EXPORT_SYMBOL(irq_poll_disable); /** * irq_poll_enable - Enable iopoll on this @iop * @iop: The parent iopoll structure * * Description: * Enable iopoll on this @iop. Note that the handler run will not be * scheduled, it will only mark it as active. **/
void irq_poll_enable(struct irq_poll *iop) { BUG_ON(!test_bit(IRQ_POLL_F_SCHED, &iop->state)); smp_mb__before_atomic(); clear_bit_unlock(IRQ_POLL_F_SCHED, &iop->state); }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe3286.49%133.33%
Christoph Hellwig410.81%133.33%
Peter Zijlstra12.70%133.33%
Total37100.00%3100.00%

EXPORT_SYMBOL(irq_poll_enable); /** * irq_poll_init - Initialize this @iop * @iop: The parent iopoll structure * @weight: The default weight (or command completion budget) * @poll_fn: The handler to invoke * * Description: * Initialize and enable this irq_poll structure. **/
void irq_poll_init(struct irq_poll *iop, int weight, irq_poll_fn *poll_fn) { memset(iop, 0, sizeof(*iop)); INIT_LIST_HEAD(&iop->list); iop->weight = weight; iop->poll = poll_fn; }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe4794.00%150.00%
Christoph Hellwig36.00%150.00%
Total50100.00%2100.00%

EXPORT_SYMBOL(irq_poll_init);
static int irq_poll_cpu_dead(unsigned int cpu) { /* * If a CPU goes away, splice its entries to the current CPU * and trigger a run of the softirq */ local_irq_disable(); list_splice_init(&per_cpu(blk_cpu_iopoll, cpu), this_cpu_ptr(&blk_cpu_iopoll)); __raise_softirq_irqoff(IRQ_POLL_SOFTIRQ); local_irq_enable(); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe3583.33%240.00%
Sebastian Andrzej Siewior49.52%120.00%
Christoph Lameter24.76%120.00%
Christoph Hellwig12.38%120.00%
Total42100.00%5100.00%


static __init int irq_poll_setup(void) { int i; for_each_possible_cpu(i) INIT_LIST_HEAD(&per_cpu(blk_cpu_iopoll, i)); open_softirq(IRQ_POLL_SOFTIRQ, irq_poll_softirq); cpuhp_setup_state_nocalls(CPUHP_IRQ_POLL_DEAD, "irq_poll:dead", NULL, irq_poll_cpu_dead); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe3777.08%133.33%
Sebastian Andrzej Siewior816.67%133.33%
Christoph Hellwig36.25%133.33%
Total48100.00%3100.00%

subsys_initcall(irq_poll_setup);

Overall Contributors

PersonTokensPropCommitsCommitProp
Jens Axboe51983.44%426.67%
Christoph Hellwig7912.70%533.33%
Sebastian Andrzej Siewior121.93%16.67%
Christoph Lameter60.96%16.67%
Fabian Frederick20.32%16.67%
Peter Zijlstra20.32%16.67%
Greg Kroah-Hartman10.16%16.67%
Emese Revfy10.16%16.67%
Total622100.00%15100.00%
Directory: lib
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