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author | 2015-08-04 12:17:53 -0700 | |
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committer | 2015-08-04 15:44:42 -0700 | |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/block/blk-iopoll.c | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/block/blk-iopoll.c')
-rw-r--r-- | kernel/block/blk-iopoll.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/kernel/block/blk-iopoll.c b/kernel/block/blk-iopoll.c new file mode 100644 index 000000000..3e21e31d0 --- /dev/null +++ b/kernel/block/blk-iopoll.c @@ -0,0 +1,227 @@ +/* + * 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/blkdev.h> +#include <linux/interrupt.h> +#include <linux/cpu.h> +#include <linux/blk-iopoll.h> +#include <linux/delay.h> + +#include "blk.h" + +static unsigned int blk_iopoll_budget __read_mostly = 256; + +static DEFINE_PER_CPU(struct list_head, blk_cpu_iopoll); + +/** + * blk_iopoll_sched - Schedule a run of the iopoll handler + * @iop: The parent iopoll structure + * + * Description: + * Add this blk_iopoll structure to the pending poll list and trigger the + * raise of the blk iopoll softirq. The driver must already have gotten a + * successful return from blk_iopoll_sched_prep() before calling this. + **/ +void blk_iopoll_sched(struct blk_iopoll *iop) +{ + unsigned long flags; + + local_irq_save(flags); + list_add_tail(&iop->list, this_cpu_ptr(&blk_cpu_iopoll)); + __raise_softirq_irqoff(BLOCK_IOPOLL_SOFTIRQ); + local_irq_restore(flags); + preempt_check_resched_rt(); +} +EXPORT_SYMBOL(blk_iopoll_sched); + +/** + * __blk_iopoll_complete - Mark this @iop as un-polled again + * @iop: The parent iopoll structure + * + * Description: + * See blk_iopoll_complete(). This function must be called with interrupts + * disabled. + **/ +void __blk_iopoll_complete(struct blk_iopoll *iop) +{ + list_del(&iop->list); + smp_mb__before_atomic(); + clear_bit_unlock(IOPOLL_F_SCHED, &iop->state); +} +EXPORT_SYMBOL(__blk_iopoll_complete); + +/** + * blk_iopoll_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 blk_iopoll_sched_prep() + * is called. + **/ +void blk_iopoll_complete(struct blk_iopoll *iop) +{ + unsigned long flags; + + local_irq_save(flags); + __blk_iopoll_complete(iop); + local_irq_restore(flags); +} +EXPORT_SYMBOL(blk_iopoll_complete); + +static void blk_iopoll_softirq(struct softirq_action *h) +{ + struct list_head *list = this_cpu_ptr(&blk_cpu_iopoll); + int rearm = 0, budget = blk_iopoll_budget; + unsigned long start_time = jiffies; + + local_irq_disable(); + + while (!list_empty(list)) { + struct blk_iopoll *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 blk_iopoll, list); + + weight = iop->weight; + work = 0; + if (test_bit(IOPOLL_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 (blk_iopoll_disable_pending(iop)) + __blk_iopoll_complete(iop); + else + list_move_tail(&iop->list, list); + } + } + + if (rearm) + __raise_softirq_irqoff(BLOCK_IOPOLL_SOFTIRQ); + + local_irq_enable(); + preempt_check_resched_rt(); +} + +/** + * blk_iopoll_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 blk_iopoll_disable(struct blk_iopoll *iop) +{ + set_bit(IOPOLL_F_DISABLE, &iop->state); + while (test_and_set_bit(IOPOLL_F_SCHED, &iop->state)) + msleep(1); + clear_bit(IOPOLL_F_DISABLE, &iop->state); +} +EXPORT_SYMBOL(blk_iopoll_disable); + +/** + * blk_iopoll_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 blk_iopoll_enable(struct blk_iopoll *iop) +{ + BUG_ON(!test_bit(IOPOLL_F_SCHED, &iop->state)); + smp_mb__before_atomic(); + clear_bit_unlock(IOPOLL_F_SCHED, &iop->state); +} +EXPORT_SYMBOL(blk_iopoll_enable); + +/** + * blk_iopoll_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 this blk_iopoll structure. Before being actively used, the + * driver must call blk_iopoll_enable(). + **/ +void blk_iopoll_init(struct blk_iopoll *iop, int weight, blk_iopoll_fn *poll_fn) +{ + memset(iop, 0, sizeof(*iop)); + INIT_LIST_HEAD(&iop->list); + iop->weight = weight; + iop->poll = poll_fn; + set_bit(IOPOLL_F_SCHED, &iop->state); +} +EXPORT_SYMBOL(blk_iopoll_init); + +static int blk_iopoll_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + /* + * If a CPU goes away, splice its entries to the current CPU + * and trigger a run of the softirq + */ + if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { + int cpu = (unsigned long) hcpu; + + local_irq_disable(); + list_splice_init(&per_cpu(blk_cpu_iopoll, cpu), + this_cpu_ptr(&blk_cpu_iopoll)); + __raise_softirq_irqoff(BLOCK_IOPOLL_SOFTIRQ); + local_irq_enable(); + preempt_check_resched_rt(); + } + + return NOTIFY_OK; +} + +static struct notifier_block blk_iopoll_cpu_notifier = { + .notifier_call = blk_iopoll_cpu_notify, +}; + +static __init int blk_iopoll_setup(void) +{ + int i; + + for_each_possible_cpu(i) + INIT_LIST_HEAD(&per_cpu(blk_cpu_iopoll, i)); + + open_softirq(BLOCK_IOPOLL_SOFTIRQ, blk_iopoll_softirq); + register_hotcpu_notifier(&blk_iopoll_cpu_notifier); + return 0; +} +subsys_initcall(blk_iopoll_setup); |