IB/ehca: Add driver for IBM eHCA InfiniBand adapters

Add a driver for IBM GX bus InfiniBand adapters, which are usable with
some pSeries/System p systems.

Signed-off-by: Heiko J Schick <schickhj.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 762 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
new file mode 100644
index 00000000000..2a65b5be197
--- /dev/null
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -0,0 +1,762 @@
+/*
+ *  IBM eServer eHCA Infiniband device driver for Linux on POWER
+ *
+ *  Functions for EQs, NEQs and interrupts
+ *
+ *  Authors: Heiko J Schick <schickhj@de.ibm.com>
+ *           Khadija Souissi <souissi@de.ibm.com>
+ *
+ *  Copyright (c) 2005 IBM Corporation
+ *
+ *  All rights reserved.
+ *
+ *  This source code is distributed under a dual license of GPL v2.0 and OpenIB
+ *  BSD.
+ *
+ * OpenIB BSD License
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials
+ * provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
+ * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "ehca_classes.h"
+#include "ehca_irq.h"
+#include "ehca_iverbs.h"
+#include "ehca_tools.h"
+#include "hcp_if.h"
+#include "hipz_fns.h"
+
+#define EQE_COMPLETION_EVENT   EHCA_BMASK_IBM(1,1)
+#define EQE_CQ_QP_NUMBER       EHCA_BMASK_IBM(8,31)
+#define EQE_EE_IDENTIFIER      EHCA_BMASK_IBM(2,7)
+#define EQE_CQ_NUMBER          EHCA_BMASK_IBM(8,31)
+#define EQE_QP_NUMBER          EHCA_BMASK_IBM(8,31)
+#define EQE_QP_TOKEN           EHCA_BMASK_IBM(32,63)
+#define EQE_CQ_TOKEN           EHCA_BMASK_IBM(32,63)
+
+#define NEQE_COMPLETION_EVENT  EHCA_BMASK_IBM(1,1)
+#define NEQE_EVENT_CODE        EHCA_BMASK_IBM(2,7)
+#define NEQE_PORT_NUMBER       EHCA_BMASK_IBM(8,15)
+#define NEQE_PORT_AVAILABILITY EHCA_BMASK_IBM(16,16)
+
+#define ERROR_DATA_LENGTH      EHCA_BMASK_IBM(52,63)
+#define ERROR_DATA_TYPE        EHCA_BMASK_IBM(0,7)
+
+#ifdef CONFIG_INFINIBAND_EHCA_SCALING
+
+static void queue_comp_task(struct ehca_cq *__cq);
+
+static struct ehca_comp_pool* pool;
+static struct notifier_block comp_pool_callback_nb;
+
+#endif
+
+static inline void comp_event_callback(struct ehca_cq *cq)
+{
+	if (!cq->ib_cq.comp_handler)
+		return;
+
+	spin_lock(&cq->cb_lock);
+	cq->ib_cq.comp_handler(&cq->ib_cq, cq->ib_cq.cq_context);
+	spin_unlock(&cq->cb_lock);
+
+	return;
+}
+
+static void print_error_data(struct ehca_shca * shca, void* data,
+			     u64* rblock, int length)
+{
+	u64 type = EHCA_BMASK_GET(ERROR_DATA_TYPE, rblock[2]);
+	u64 resource = rblock[1];
+
+	switch (type) {
+	case 0x1: /* Queue Pair */
+	{
+		struct ehca_qp *qp = (struct ehca_qp*)data;
+
+		/* only print error data if AER is set */
+		if (rblock[6] == 0)
+			return;
+
+		ehca_err(&shca->ib_device,
+			 "QP 0x%x (resource=%lx) has errors.",
+			 qp->ib_qp.qp_num, resource);
+		break;
+	}
+	case 0x4: /* Completion Queue */
+	{
+		struct ehca_cq *cq = (struct ehca_cq*)data;
+
+		ehca_err(&shca->ib_device,
+			 "CQ 0x%x (resource=%lx) has errors.",
+			 cq->cq_number, resource);
+		break;
+	}
+	default:
+		ehca_err(&shca->ib_device,
+			 "Unknown errror type: %lx on %s.",
+			 type, shca->ib_device.name);
+		break;
+	}
+
+	ehca_err(&shca->ib_device, "Error data is available: %lx.", resource);
+	ehca_err(&shca->ib_device, "EHCA ----- error data begin "
+		 "---------------------------------------------------");
+	ehca_dmp(rblock, length, "resource=%lx", resource);
+	ehca_err(&shca->ib_device, "EHCA ----- error data end "
+		 "----------------------------------------------------");
+
+	return;
+}
+
+int ehca_error_data(struct ehca_shca *shca, void *data,
+		    u64 resource)
+{
+
+	unsigned long ret;
+	u64 *rblock;
+	unsigned long block_count;
+
+	rblock = kzalloc(H_CB_ALIGNMENT, GFP_KERNEL);
+	if (!rblock) {
+		ehca_err(&shca->ib_device, "Cannot allocate rblock memory.");
+		ret = -ENOMEM;
+		goto error_data1;
+	}
+
+	ret = hipz_h_error_data(shca->ipz_hca_handle,
+				resource,
+				rblock,
+				&block_count);
+
+	if (ret == H_R_STATE) {
+		ehca_err(&shca->ib_device,
+			 "No error data is available: %lx.", resource);
+	}
+	else if (ret == H_SUCCESS) {
+		int length;
+
+		length = EHCA_BMASK_GET(ERROR_DATA_LENGTH, rblock[0]);
+
+		if (length > PAGE_SIZE)
+			length = PAGE_SIZE;
+
+		print_error_data(shca, data, rblock, length);
+	}
+	else {
+		ehca_err(&shca->ib_device,
+			 "Error data could not be fetched: %lx", resource);
+	}
+
+	kfree(rblock);
+
+error_data1:
+	return ret;
+
+}
+
+static void qp_event_callback(struct ehca_shca *shca,
+			      u64 eqe,
+			      enum ib_event_type event_type)
+{
+	struct ib_event event;
+	struct ehca_qp *qp;
+	unsigned long flags;
+	u32 token = EHCA_BMASK_GET(EQE_QP_TOKEN, eqe);
+
+	spin_lock_irqsave(&ehca_qp_idr_lock, flags);
+	qp = idr_find(&ehca_qp_idr, token);
+	spin_unlock_irqrestore(&ehca_qp_idr_lock, flags);
+
+
+	if (!qp)
+		return;
+
+	ehca_error_data(shca, qp, qp->ipz_qp_handle.handle);
+
+	if (!qp->ib_qp.event_handler)
+		return;
+
+	event.device     = &shca->ib_device;
+	event.event      = event_type;
+	event.element.qp = &qp->ib_qp;
+
+	qp->ib_qp.event_handler(&event, qp->ib_qp.qp_context);
+
+	return;
+}
+
+static void cq_event_callback(struct ehca_shca *shca,
+					  u64 eqe)
+{
+	struct ehca_cq *cq;
+	unsigned long flags;
+	u32 token = EHCA_BMASK_GET(EQE_CQ_TOKEN, eqe);
+
+	spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+	cq = idr_find(&ehca_cq_idr, token);
+	spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+
+	if (!cq)
+		return;
+
+	ehca_error_data(shca, cq, cq->ipz_cq_handle.handle);
+
+	return;
+}
+
+static void parse_identifier(struct ehca_shca *shca, u64 eqe)
+{
+	u8 identifier = EHCA_BMASK_GET(EQE_EE_IDENTIFIER, eqe);
+
+	switch (identifier) {
+	case 0x02: /* path migrated */
+		qp_event_callback(shca, eqe, IB_EVENT_PATH_MIG);
+		break;
+	case 0x03: /* communication established */
+		qp_event_callback(shca, eqe, IB_EVENT_COMM_EST);
+		break;
+	case 0x04: /* send queue drained */
+		qp_event_callback(shca, eqe, IB_EVENT_SQ_DRAINED);
+		break;
+	case 0x05: /* QP error */
+	case 0x06: /* QP error */
+		qp_event_callback(shca, eqe, IB_EVENT_QP_FATAL);
+		break;
+	case 0x07: /* CQ error */
+	case 0x08: /* CQ error */
+		cq_event_callback(shca, eqe);
+		break;
+	case 0x09: /* MRMWPTE error */
+		ehca_err(&shca->ib_device, "MRMWPTE error.");
+		break;
+	case 0x0A: /* port event */
+		ehca_err(&shca->ib_device, "Port event.");
+		break;
+	case 0x0B: /* MR access error */
+		ehca_err(&shca->ib_device, "MR access error.");
+		break;
+	case 0x0C: /* EQ error */
+		ehca_err(&shca->ib_device, "EQ error.");
+		break;
+	case 0x0D: /* P/Q_Key mismatch */
+		ehca_err(&shca->ib_device, "P/Q_Key mismatch.");
+		break;
+	case 0x10: /* sampling complete */
+		ehca_err(&shca->ib_device, "Sampling complete.");
+		break;
+	case 0x11: /* unaffiliated access error */
+		ehca_err(&shca->ib_device, "Unaffiliated access error.");
+		break;
+	case 0x12: /* path migrating error */
+		ehca_err(&shca->ib_device, "Path migration error.");
+		break;
+	case 0x13: /* interface trace stopped */
+		ehca_err(&shca->ib_device, "Interface trace stopped.");
+		break;
+	case 0x14: /* first error capture info available */
+	default:
+		ehca_err(&shca->ib_device, "Unknown identifier: %x on %s.",
+			 identifier, shca->ib_device.name);
+		break;
+	}
+
+	return;
+}
+
+static void parse_ec(struct ehca_shca *shca, u64 eqe)
+{
+	struct ib_event event;
+	u8 ec   = EHCA_BMASK_GET(NEQE_EVENT_CODE, eqe);
+	u8 port = EHCA_BMASK_GET(NEQE_PORT_NUMBER, eqe);
+
+	switch (ec) {
+	case 0x30: /* port availability change */
+		if (EHCA_BMASK_GET(NEQE_PORT_AVAILABILITY, eqe)) {
+			ehca_info(&shca->ib_device,
+				  "port %x is active.", port);
+			event.device = &shca->ib_device;
+			event.event = IB_EVENT_PORT_ACTIVE;
+			event.element.port_num = port;
+			shca->sport[port - 1].port_state = IB_PORT_ACTIVE;
+			ib_dispatch_event(&event);
+		} else {
+			ehca_info(&shca->ib_device,
+				  "port %x is inactive.", port);
+			event.device = &shca->ib_device;
+			event.event = IB_EVENT_PORT_ERR;
+			event.element.port_num = port;
+			shca->sport[port - 1].port_state = IB_PORT_DOWN;
+			ib_dispatch_event(&event);
+		}
+		break;
+	case 0x31:
+		/* port configuration change
+		 * disruptive change is caused by
+		 * LID, PKEY or SM change
+		 */
+		ehca_warn(&shca->ib_device,
+			  "disruptive port %x configuration change", port);
+
+		ehca_info(&shca->ib_device,
+			 "port %x is inactive.", port);
+		event.device = &shca->ib_device;
+		event.event = IB_EVENT_PORT_ERR;
+		event.element.port_num = port;
+		shca->sport[port - 1].port_state = IB_PORT_DOWN;
+		ib_dispatch_event(&event);
+
+		ehca_info(&shca->ib_device,
+			 "port %x is active.", port);
+		event.device = &shca->ib_device;
+		event.event = IB_EVENT_PORT_ACTIVE;
+		event.element.port_num = port;
+		shca->sport[port - 1].port_state = IB_PORT_ACTIVE;
+		ib_dispatch_event(&event);
+		break;
+	case 0x32: /* adapter malfunction */
+		ehca_err(&shca->ib_device, "Adapter malfunction.");
+		break;
+	case 0x33:  /* trace stopped */
+		ehca_err(&shca->ib_device, "Traced stopped.");
+		break;
+	default:
+		ehca_err(&shca->ib_device, "Unknown event code: %x on %s.",
+			 ec, shca->ib_device.name);
+		break;
+	}
+
+	return;
+}
+
+static inline void reset_eq_pending(struct ehca_cq *cq)
+{
+	u64 CQx_EP;
+	struct h_galpa gal = cq->galpas.kernel;
+
+	hipz_galpa_store_cq(gal, cqx_ep, 0x0);
+	CQx_EP = hipz_galpa_load(gal, CQTEMM_OFFSET(cqx_ep));
+
+	return;
+}
+
+irqreturn_t ehca_interrupt_neq(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct ehca_shca *shca = (struct ehca_shca*)dev_id;
+
+	tasklet_hi_schedule(&shca->neq.interrupt_task);
+
+	return IRQ_HANDLED;
+}
+
+void ehca_tasklet_neq(unsigned long data)
+{
+	struct ehca_shca *shca = (struct ehca_shca*)data;
+	struct ehca_eqe *eqe;
+	u64 ret;
+
+	eqe = (struct ehca_eqe *)ehca_poll_eq(shca, &shca->neq);
+
+	while (eqe) {
+		if (!EHCA_BMASK_GET(NEQE_COMPLETION_EVENT, eqe->entry))
+			parse_ec(shca, eqe->entry);
+
+		eqe = (struct ehca_eqe *)ehca_poll_eq(shca, &shca->neq);
+	}
+
+	ret = hipz_h_reset_event(shca->ipz_hca_handle,
+				 shca->neq.ipz_eq_handle, 0xFFFFFFFFFFFFFFFFL);
+
+	if (ret != H_SUCCESS)
+		ehca_err(&shca->ib_device, "Can't clear notification events.");
+
+	return;
+}
+
+irqreturn_t ehca_interrupt_eq(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct ehca_shca *shca = (struct ehca_shca*)dev_id;
+
+	tasklet_hi_schedule(&shca->eq.interrupt_task);
+
+	return IRQ_HANDLED;
+}
+
+void ehca_tasklet_eq(unsigned long data)
+{
+	struct ehca_shca *shca = (struct ehca_shca*)data;
+	struct ehca_eqe *eqe;
+	int int_state;
+	int query_cnt = 0;
+
+	do {
+		eqe = (struct ehca_eqe *)ehca_poll_eq(shca, &shca->eq);
+
+		if ((shca->hw_level >= 2) && eqe)
+			int_state = 1;
+		else
+			int_state = 0;
+
+		while ((int_state == 1) || eqe) {
+			while (eqe) {
+				u64 eqe_value = eqe->entry;
+
+				ehca_dbg(&shca->ib_device,
+					 "eqe_value=%lx", eqe_value);
+
+				/* TODO: better structure */
+				if (EHCA_BMASK_GET(EQE_COMPLETION_EVENT,
+						   eqe_value)) {
+					unsigned long flags;
+					u32 token;
+					struct ehca_cq *cq;
+
+					ehca_dbg(&shca->ib_device,
+						 "... completion event");
+					token =
+						EHCA_BMASK_GET(EQE_CQ_TOKEN,
+							       eqe_value);
+					spin_lock_irqsave(&ehca_cq_idr_lock,
+							  flags);
+					cq = idr_find(&ehca_cq_idr, token);
+
+					if (cq == NULL) {
+						spin_unlock(&ehca_cq_idr_lock);
+						break;
+					}
+
+					reset_eq_pending(cq);
+#ifdef CONFIG_INFINIBAND_EHCA_SCALING
+					queue_comp_task(cq);
+					spin_unlock_irqrestore(&ehca_cq_idr_lock,
+							       flags);
+#else
+					spin_unlock_irqrestore(&ehca_cq_idr_lock,
+							       flags);
+					comp_event_callback(cq);
+#endif
+				} else {
+					ehca_dbg(&shca->ib_device,
+						 "... non completion event");
+					parse_identifier(shca, eqe_value);
+				}
+				eqe =
+					(struct ehca_eqe *)ehca_poll_eq(shca,
+								    &shca->eq);
+			}
+
+			if (shca->hw_level >= 2) {
+				int_state =
+				    hipz_h_query_int_state(shca->ipz_hca_handle,
+							   shca->eq.ist);
+				query_cnt++;
+				iosync();
+				if (query_cnt >= 100) {
+					query_cnt = 0;
+					int_state = 0;
+				}
+			}
+			eqe = (struct ehca_eqe *)ehca_poll_eq(shca, &shca->eq);
+
+		}
+	} while (int_state != 0);
+
+	return;
+}
+
+#ifdef CONFIG_INFINIBAND_EHCA_SCALING
+
+static inline int find_next_online_cpu(struct ehca_comp_pool* pool)
+{
+	unsigned long flags_last_cpu;
+
+	if (ehca_debug_level)
+		ehca_dmp(&cpu_online_map, sizeof(cpumask_t), "");
+
+	spin_lock_irqsave(&pool->last_cpu_lock, flags_last_cpu);
+	pool->last_cpu = next_cpu(pool->last_cpu, cpu_online_map);
+	if (pool->last_cpu == NR_CPUS)
+		pool->last_cpu = first_cpu(cpu_online_map);
+	spin_unlock_irqrestore(&pool->last_cpu_lock, flags_last_cpu);
+
+	return pool->last_cpu;
+}
+
+static void __queue_comp_task(struct ehca_cq *__cq,
+			      struct ehca_cpu_comp_task *cct)
+{
+	unsigned long flags_cct;
+	unsigned long flags_cq;
+
+	spin_lock_irqsave(&cct->task_lock, flags_cct);
+	spin_lock_irqsave(&__cq->task_lock, flags_cq);
+
+	if (__cq->nr_callbacks == 0) {
+		__cq->nr_callbacks++;
+		list_add_tail(&__cq->entry, &cct->cq_list);
+		cct->cq_jobs++;
+		wake_up(&cct->wait_queue);
+	}
+	else
+		__cq->nr_callbacks++;
+
+	spin_unlock_irqrestore(&__cq->task_lock, flags_cq);
+	spin_unlock_irqrestore(&cct->task_lock, flags_cct);
+}
+
+static void queue_comp_task(struct ehca_cq *__cq)
+{
+	int cpu;
+	int cpu_id;
+	struct ehca_cpu_comp_task *cct;
+
+	cpu = get_cpu();
+	cpu_id = find_next_online_cpu(pool);
+
+	BUG_ON(!cpu_online(cpu_id));
+
+	cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id);
+
+	if (cct->cq_jobs > 0) {
+		cpu_id = find_next_online_cpu(pool);
+		cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id);
+	}
+
+	__queue_comp_task(__cq, cct);
+
+	put_cpu();
+
+	return;
+}
+
+static void run_comp_task(struct ehca_cpu_comp_task* cct)
+{
+	struct ehca_cq *cq;
+	unsigned long flags_cct;
+	unsigned long flags_cq;
+
+	spin_lock_irqsave(&cct->task_lock, flags_cct);
+
+	while (!list_empty(&cct->cq_list)) {
+		cq = list_entry(cct->cq_list.next, struct ehca_cq, entry);
+		spin_unlock_irqrestore(&cct->task_lock, flags_cct);
+		comp_event_callback(cq);
+		spin_lock_irqsave(&cct->task_lock, flags_cct);
+
+		spin_lock_irqsave(&cq->task_lock, flags_cq);
+		cq->nr_callbacks--;
+		if (cq->nr_callbacks == 0) {
+			list_del_init(cct->cq_list.next);
+			cct->cq_jobs--;
+		}
+		spin_unlock_irqrestore(&cq->task_lock, flags_cq);
+
+	}
+
+	spin_unlock_irqrestore(&cct->task_lock, flags_cct);
+
+	return;
+}
+
+static int comp_task(void *__cct)
+{
+	struct ehca_cpu_comp_task* cct = __cct;
+	DECLARE_WAITQUEUE(wait, current);
+
+	set_current_state(TASK_INTERRUPTIBLE);
+	while(!kthread_should_stop()) {
+		add_wait_queue(&cct->wait_queue, &wait);
+
+		if (list_empty(&cct->cq_list))
+			schedule();
+		else
+			__set_current_state(TASK_RUNNING);
+
+		remove_wait_queue(&cct->wait_queue, &wait);
+
+		if (!list_empty(&cct->cq_list))
+			run_comp_task(__cct);
+
+		set_current_state(TASK_INTERRUPTIBLE);
+	}
+	__set_current_state(TASK_RUNNING);
+
+	return 0;
+}
+
+static struct task_struct *create_comp_task(struct ehca_comp_pool *pool,
+					    int cpu)
+{
+	struct ehca_cpu_comp_task *cct;
+
+	cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+	spin_lock_init(&cct->task_lock);
+	INIT_LIST_HEAD(&cct->cq_list);
+	init_waitqueue_head(&cct->wait_queue);
+	cct->task = kthread_create(comp_task, cct, "ehca_comp/%d", cpu);
+
+	return cct->task;
+}
+
+static void destroy_comp_task(struct ehca_comp_pool *pool,
+			      int cpu)
+{
+	struct ehca_cpu_comp_task *cct;
+	struct task_struct *task;
+	unsigned long flags_cct;
+
+	cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+
+	spin_lock_irqsave(&cct->task_lock, flags_cct);
+
+	task = cct->task;
+	cct->task = NULL;
+	cct->cq_jobs = 0;
+
+	spin_unlock_irqrestore(&cct->task_lock, flags_cct);
+
+	if (task)
+		kthread_stop(task);
+
+	return;
+}
+
+static void take_over_work(struct ehca_comp_pool *pool,
+			   int cpu)
+{
+	struct ehca_cpu_comp_task *cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+	LIST_HEAD(list);
+	struct ehca_cq *cq;
+	unsigned long flags_cct;
+
+	spin_lock_irqsave(&cct->task_lock, flags_cct);
+
+	list_splice_init(&cct->cq_list, &list);
+
+	while(!list_empty(&list)) {
+	       cq = list_entry(cct->cq_list.next, struct ehca_cq, entry);
+
+	       list_del(&cq->entry);
+	       __queue_comp_task(cq, per_cpu_ptr(pool->cpu_comp_tasks,
+						 smp_processor_id()));
+	}
+
+	spin_unlock_irqrestore(&cct->task_lock, flags_cct);
+
+}
+
+static int comp_pool_callback(struct notifier_block *nfb,
+			      unsigned long action,
+			      void *hcpu)
+{
+	unsigned int cpu = (unsigned long)hcpu;
+	struct ehca_cpu_comp_task *cct;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		ehca_gen_dbg("CPU: %x (CPU_PREPARE)", cpu);
+		if(!create_comp_task(pool, cpu)) {
+			ehca_gen_err("Can't create comp_task for cpu: %x", cpu);
+			return NOTIFY_BAD;
+		}
+		break;
+	case CPU_UP_CANCELED:
+		ehca_gen_dbg("CPU: %x (CPU_CANCELED)", cpu);
+		cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+		kthread_bind(cct->task, any_online_cpu(cpu_online_map));
+		destroy_comp_task(pool, cpu);
+		break;
+	case CPU_ONLINE:
+		ehca_gen_dbg("CPU: %x (CPU_ONLINE)", cpu);
+		cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
+		kthread_bind(cct->task, cpu);
+		wake_up_process(cct->task);
+		break;
+	case CPU_DOWN_PREPARE:
+		ehca_gen_dbg("CPU: %x (CPU_DOWN_PREPARE)", cpu);
+		break;
+	case CPU_DOWN_FAILED:
+		ehca_gen_dbg("CPU: %x (CPU_DOWN_FAILED)", cpu);
+		break;
+	case CPU_DEAD:
+		ehca_gen_dbg("CPU: %x (CPU_DEAD)", cpu);
+		destroy_comp_task(pool, cpu);
+		take_over_work(pool, cpu);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+#endif
+
+int ehca_create_comp_pool(void)
+{
+#ifdef CONFIG_INFINIBAND_EHCA_SCALING
+	int cpu;
+	struct task_struct *task;
+
+	pool = kzalloc(sizeof(struct ehca_comp_pool), GFP_KERNEL);
+	if (pool == NULL)
+		return -ENOMEM;
+
+	spin_lock_init(&pool->last_cpu_lock);
+	pool->last_cpu = any_online_cpu(cpu_online_map);
+
+	pool->cpu_comp_tasks = alloc_percpu(struct ehca_cpu_comp_task);
+	if (pool->cpu_comp_tasks == NULL) {
+		kfree(pool);
+		return -EINVAL;
+	}
+
+	for_each_online_cpu(cpu) {
+		task = create_comp_task(pool, cpu);
+		if (task) {
+			kthread_bind(task, cpu);
+			wake_up_process(task);
+		}
+	}
+
+	comp_pool_callback_nb.notifier_call = comp_pool_callback;
+	comp_pool_callback_nb.priority =0;
+	register_cpu_notifier(&comp_pool_callback_nb);
+#endif
+
+	return 0;
+}
+
+void ehca_destroy_comp_pool(void)
+{
+#ifdef CONFIG_INFINIBAND_EHCA_SCALING
+	int i;
+
+	unregister_cpu_notifier(&comp_pool_callback_nb);
+
+	for (i = 0; i < NR_CPUS; i++) {
+		if (cpu_online(i))
+			destroy_comp_task(pool, i);
+	}
+#endif
+
+	return;
+}