/* * Functions related to interrupt-poll handling in the block layer. This * is similar to NAPI for network devices. */ #include #include #include #include #include #include #include #include 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); } 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); } /** * 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); } 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(); } /** * 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); } 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); } 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; } 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; } 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; } subsys_initcall(irq_poll_setup); Kinglong Mee <kinglongmee@gmail.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat
-rw-r--r--fs/nfsd/nfs4layouts.c5
-rw-r--r--fs/nfsd/nfs4state.c19
-rw-r--r--fs/nfsd/state.h4
3 files changed, 13 insertions, 15 deletions
diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c