From 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 Mon Sep 17 00:00:00 2001 From: Yunhong Jiang Date: Tue, 4 Aug 2015 12:17:53 -0700 Subject: 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 Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior 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 --- kernel/block/blk-softirq.c | 189 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 189 insertions(+) create mode 100644 kernel/block/blk-softirq.c (limited to 'kernel/block/blk-softirq.c') diff --git a/kernel/block/blk-softirq.c b/kernel/block/blk-softirq.c new file mode 100644 index 000000000..81c3c0a62 --- /dev/null +++ b/kernel/block/blk-softirq.c @@ -0,0 +1,189 @@ +/* + * Functions related to softirq rq completions + */ +#include +#include +#include +#include +#include +#include +#include +#include + +#include "blk.h" + +static DEFINE_PER_CPU(struct list_head, blk_cpu_done); + +/* + * Softirq action handler - move entries to local list and loop over them + * while passing them to the queue registered handler. + */ +static void blk_done_softirq(struct softirq_action *h) +{ + struct list_head *cpu_list, local_list; + + local_irq_disable(); + cpu_list = this_cpu_ptr(&blk_cpu_done); + list_replace_init(cpu_list, &local_list); + local_irq_enable(); + + while (!list_empty(&local_list)) { + struct request *rq; + + rq = list_entry(local_list.next, struct request, ipi_list); + list_del_init(&rq->ipi_list); + rq->q->softirq_done_fn(rq); + } +} + +#ifdef CONFIG_SMP +static void trigger_softirq(void *data) +{ + struct request *rq = data; + unsigned long flags; + struct list_head *list; + + local_irq_save(flags); + list = this_cpu_ptr(&blk_cpu_done); + list_add_tail(&rq->ipi_list, list); + + if (list->next == &rq->ipi_list) + raise_softirq_irqoff(BLOCK_SOFTIRQ); + + local_irq_restore(flags); + preempt_check_resched_rt(); +} + +/* + * Setup and invoke a run of 'trigger_softirq' on the given cpu. + */ +static int raise_blk_irq(int cpu, struct request *rq) +{ + if (cpu_online(cpu)) { + struct call_single_data *data = &rq->csd; + + data->func = trigger_softirq; + data->info = rq; + data->flags = 0; + + smp_call_function_single_async(cpu, data); + return 0; + } + + return 1; +} +#else /* CONFIG_SMP */ +static int raise_blk_irq(int cpu, struct request *rq) +{ + return 1; +} +#endif + +static int blk_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_done, cpu), + this_cpu_ptr(&blk_cpu_done)); + raise_softirq_irqoff(BLOCK_SOFTIRQ); + local_irq_enable(); + preempt_check_resched_rt(); + } + + return NOTIFY_OK; +} + +static struct notifier_block blk_cpu_notifier = { + .notifier_call = blk_cpu_notify, +}; + +void __blk_complete_request(struct request *req) +{ + int ccpu, cpu; + struct request_queue *q = req->q; + unsigned long flags; + bool shared = false; + + BUG_ON(!q->softirq_done_fn); + + local_irq_save(flags); + cpu = smp_processor_id(); + + /* + * Select completion CPU + */ + if (req->cpu != -1) { + ccpu = req->cpu; + if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags)) + shared = cpus_share_cache(cpu, ccpu); + } else + ccpu = cpu; + + /* + * If current CPU and requested CPU share a cache, run the softirq on + * the current CPU. One might concern this is just like + * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is + * running in interrupt handler, and currently I/O controller doesn't + * support multiple interrupts, so current CPU is unique actually. This + * avoids IPI sending from current CPU to the first CPU of a group. + */ + if (ccpu == cpu || shared) { + struct list_head *list; +do_local: + list = this_cpu_ptr(&blk_cpu_done); + list_add_tail(&req->ipi_list, list); + + /* + * if the list only contains our just added request, + * signal a raise of the softirq. If there are already + * entries there, someone already raised the irq but it + * hasn't run yet. + */ + if (list->next == &req->ipi_list) + raise_softirq_irqoff(BLOCK_SOFTIRQ); + } else if (raise_blk_irq(ccpu, req)) + goto do_local; + + local_irq_restore(flags); + preempt_check_resched_rt(); +} + +/** + * blk_complete_request - end I/O on a request + * @req: the request being processed + * + * Description: + * Ends all I/O on a request. It does not handle partial completions, + * unless the driver actually implements this in its completion callback + * through requeueing. The actual completion happens out-of-order, + * through a softirq handler. The user must have registered a completion + * callback through blk_queue_softirq_done(). + **/ +void blk_complete_request(struct request *req) +{ + if (unlikely(blk_should_fake_timeout(req->q))) + return; + if (!blk_mark_rq_complete(req)) + __blk_complete_request(req); +} +EXPORT_SYMBOL(blk_complete_request); + +static __init int blk_softirq_init(void) +{ + int i; + + for_each_possible_cpu(i) + INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); + + open_softirq(BLOCK_SOFTIRQ, blk_done_softirq); + register_hotcpu_notifier(&blk_cpu_notifier); + return 0; +} +subsys_initcall(blk_softirq_init); -- cgit 1.2.3-korg