C++ smp_mb__after_clear_bit函数代码示例

static void gdlm_recover_done(void *arg, struct dlm_slot *slots, int num_slots,
			      int our_slot, uint32_t generation)
{
	struct gfs2_sbd *sdp = arg;
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;

	/* ensure the ls jid arrays are large enough */
	set_recover_size(sdp, slots, num_slots);

	spin_lock(&ls->ls_recover_spin);
	ls->ls_recover_start = generation;

	if (!ls->ls_recover_mount) {
		ls->ls_recover_mount = generation;
		ls->ls_jid = our_slot - 1;
	}

	if (!test_bit(DFL_UNMOUNT, &ls->ls_recover_flags))
		queue_delayed_work(gfs2_control_wq, &sdp->sd_control_work, 0);

	clear_bit(DFL_DLM_RECOVERY, &ls->ls_recover_flags);
	smp_mb__after_clear_bit();
	wake_up_bit(&ls->ls_recover_flags, DFL_DLM_RECOVERY);
	spin_unlock(&ls->ls_recover_spin);
}

fastcall void smp_invalidate_interrupt(struct pt_regs *regs)
{
	unsigned long cpu;

	cpu = get_cpu();

	if (!cpu_isset(cpu, flush_cpumask))
		goto out;
		/* 
		 * This was a BUG() but until someone can quote me the
		 * line from the intel manual that guarantees an IPI to
		 * multiple CPUs is retried _only_ on the erroring CPUs
		 * its staying as a return
		 *
		 * BUG();
		 */
		 
	if (flush_mm == per_cpu(cpu_tlbstate, cpu).active_mm) {
		if (per_cpu(cpu_tlbstate, cpu).state == TLBSTATE_OK) {
			if (flush_va == FLUSH_ALL)
				local_flush_tlb();
			else
				__flush_tlb_one(flush_va);
		} else
			leave_mm(cpu);
	}
	ack_APIC_irq();
	smp_mb__before_clear_bit();
	cpu_clear(cpu, flush_cpumask);
	smp_mb__after_clear_bit();
out:
	put_cpu_no_resched();
}

static void
__xprt_lock_write_next(struct rpc_xprt *xprt)
{
	struct rpc_task *task;

	if (test_and_set_bit(XPRT_LOCKED, &xprt->sockstate))
		return;
	if (!xprt->nocong && RPCXPRT_CONGESTED(xprt))
		goto out_unlock;
	task = rpc_wake_up_next(&xprt->resend);
	if (!task) {
		task = rpc_wake_up_next(&xprt->sending);
		if (!task)
			goto out_unlock;
	}
	if (xprt->nocong || __xprt_get_cong(xprt, task)) {
		struct rpc_rqst *req = task->tk_rqstp;
		xprt->snd_task = task;
		if (req) {
			req->rq_bytes_sent = 0;
			req->rq_ntrans++;
		}
		return;
	}
out_unlock:
	smp_mb__before_clear_bit();
	clear_bit(XPRT_LOCKED, &xprt->sockstate);
	smp_mb__after_clear_bit();
}

void arch_trigger_all_cpu_backtrace(void)
{
	int i;

	if (test_and_set_bit(0, &backtrace_flag))
		/*
                                                                  
                                                               
   */
		return;

	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);

	printk(KERN_INFO "sending NMI to all CPUs:\n");
	apic->send_IPI_all(NMI_VECTOR);

	/*                                                            */
	for (i = 0; i < 10 * 1000; i++) {
		if (cpumask_empty(to_cpumask(backtrace_mask)))
			break;
		mdelay(1);
	}

	clear_bit(0, &backtrace_flag);
	smp_mb__after_clear_bit();
}

int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
	struct inode *inode = mapping->host;
	unsigned long *bitlock = &NFS_I(inode)->flags;
	struct nfs_pageio_descriptor pgio;
	int err;

	/* Stop dirtying of new pages while we sync */
	err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
			nfs_wait_bit_killable, TASK_KILLABLE);
	if (err)
		goto out_err;

	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);

	nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
	err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
	nfs_pageio_complete(&pgio);

	clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
	smp_mb__after_clear_bit();
	wake_up_bit(bitlock, NFS_INO_FLUSHING);

	if (err < 0)
		goto out_err;
	err = pgio.pg_error;
	if (err < 0)
		goto out_err;
	return 0;
out_err:
	return err;
}

/**
 * fscache_object_lookup_negative - Note negative cookie lookup
 * @object: Object pointing to cookie to mark
 *
 * Note negative lookup, permitting those waiting to read data from an already
 * existing backing object to continue as there's no data for them to read.
 */
void fscache_object_lookup_negative(struct fscache_object *object)
{
	struct fscache_cookie *cookie = object->cookie;

	_enter("{OBJ%x,%s}",
	       object->debug_id, fscache_object_states[object->state]);

	spin_lock(&object->lock);
	if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
		fscache_stat(&fscache_n_object_lookups_negative);

		/* transit here to allow write requests to begin stacking up
		 * and read requests to begin returning ENODATA */
		object->state = FSCACHE_OBJECT_CREATING;
		spin_unlock(&object->lock);

		set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags);
		set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);

		_debug("wake up lookup %p", &cookie->flags);
		smp_mb__before_clear_bit();
		clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
		smp_mb__after_clear_bit();
		wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
		set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
	} else {
		ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
		spin_unlock(&object->lock);
	}

	_leave("");
}

/*
 * Serialize write access to sockets, in order to prevent different
 * requests from interfering with each other.
 * Also prevents TCP socket connects from colliding with writes.
 */
static int
__xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
{
	struct rpc_rqst *req = task->tk_rqstp;

	if (test_and_set_bit(XPRT_LOCKED, &xprt->sockstate)) {
		if (task == xprt->snd_task)
			return 1;
		if (task == NULL)
			return 0;
		goto out_sleep;
	}
	if (xprt->nocong || __xprt_get_cong(xprt, task)) {
		xprt->snd_task = task;
		if (req) {
			req->rq_bytes_sent = 0;
			req->rq_ntrans++;
		}
		return 1;
	}
	smp_mb__before_clear_bit();
	clear_bit(XPRT_LOCKED, &xprt->sockstate);
	smp_mb__after_clear_bit();
out_sleep:
	dprintk("RPC: %4d failed to lock socket %p\n", task->tk_pid, xprt);
	task->tk_timeout = 0;
	task->tk_status = -EAGAIN;
	if (req && req->rq_ntrans)
		rpc_sleep_on(&xprt->resend, task, NULL, NULL);
	else
		rpc_sleep_on(&xprt->sending, task, NULL, NULL);
	return 0;
}

/*
 * clearing the blocking flag will take the spinlock again.
 * After this you can't safely schedule
 */
void btrfs_clear_lock_blocking(struct extent_buffer *eb)
{
	if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) {
		spin_nested(eb);
		clear_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags);
		smp_mb__after_clear_bit();
	}
	/* exit with the spin lock held */
}

static int rtlx_release(struct inode *inode, struct file *filp)
{
	int minor = MINOR(inode->i_rdev);

	clear_bit(RTLX_STATE_OPENED, &rtlx->channel[minor].lx_state);
	smp_mb__after_clear_bit();

	return 0;
}

/*
 * Unlock cookie management lock
 */
static inline void nfs_fscache_inode_unlock(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);

	smp_mb__before_clear_bit();
	clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
	smp_mb__after_clear_bit();
	wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
}

/* Performing the configuration space reads/writes must not be done in atomic
 * context because some of the pci_* functions can sleep (mostly due to ACPI
 * use of semaphores). This function is intended to be called from a work
 * queue in process context taking a struct pciback_device as a parameter */
void pciback_do_op(struct work_struct *work)
{
	struct pciback_device *pdev = container_of(work, struct pciback_device, op_work);
	struct pci_dev *dev;
	struct xen_pci_op *op = &pdev->sh_info->op;

	dev = pciback_get_pci_dev(pdev, op->domain, op->bus, op->devfn);

	if (dev == NULL)
		op->err = XEN_PCI_ERR_dev_not_found;
	else
	{
		switch (op->cmd)
		{
			case XEN_PCI_OP_conf_read:
				op->err = pciback_config_read(dev,
					  op->offset, op->size, &op->value);
				break;
			case XEN_PCI_OP_conf_write:
				op->err = pciback_config_write(dev,
					  op->offset, op->size,	op->value);
				break;
#ifdef CONFIG_PCI_MSI
			case XEN_PCI_OP_enable_msi:
				op->err = pciback_enable_msi(pdev, dev, op);
				break;
			case XEN_PCI_OP_disable_msi:
				op->err = pciback_disable_msi(pdev, dev, op);
				break;
			case XEN_PCI_OP_enable_msix:
				op->err = pciback_enable_msix(pdev, dev, op);
				break;
			case XEN_PCI_OP_disable_msix:
				op->err = pciback_disable_msix(pdev, dev, op);
				break;
#endif
			default:
				op->err = XEN_PCI_ERR_not_implemented;
				break;
		}
	}
	/* Tell the driver domain that we're done. */ 
	wmb();
	clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
	notify_remote_via_irq(pdev->evtchn_irq);

	/* Mark that we're done. */
	smp_mb__before_clear_bit(); /* /after/ clearing PCIF_active */
	clear_bit(_PDEVF_op_active, &pdev->flags);
	smp_mb__after_clear_bit(); /* /before/ final check for work */

	/* Check to see if the driver domain tried to start another request in
	 * between clearing _XEN_PCIF_active and clearing _PDEVF_op_active. 
	*/
	test_and_schedule_op(pdev);
}

static void xprt_clear_locked(struct rpc_xprt *xprt)
{
	xprt->snd_task = NULL;
	if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
		smp_mb__before_clear_bit();
		clear_bit(XPRT_LOCKED, &xprt->state);
		smp_mb__after_clear_bit();
	} else
		schedule_work(&xprt->task_cleanup);
}

/*
 * Releases the socket for use by other requests.
 */
static void
__xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
{
	if (xprt->snd_task == task) {
		xprt->snd_task = NULL;
		smp_mb__before_clear_bit();
		clear_bit(XPRT_LOCKED, &xprt->sockstate);
		smp_mb__after_clear_bit();
		__xprt_lock_write_next(xprt);
	}
}

void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
{
	enum bdi_state bit;
	wait_queue_head_t *wqh = &congestion_wqh[rw];

	bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
	clear_bit(bit, &bdi->state);
	smp_mb__after_clear_bit();
	if (waitqueue_active(wqh))
		wake_up(wqh);
}

static void xen_idle(void)
{
	local_irq_disable();

	if (need_resched())
		local_irq_enable();
	else {
		current_thread_info()->status &= ~TS_POLLING;
		smp_mb__after_clear_bit();
		safe_halt();
		current_thread_info()->status |= TS_POLLING;
	}
}