From: Brad Peters <bpeters@redhat.com>
Date: Tue, 29 Jul 2008 14:03:10 -0400
Subject: [ppc] Event Queue overflow on eHCA adapters
Message-id: 20080729180310.8623.41936.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH RHEL5.3] Event Queue overflow on eHCA adapters
Bugzilla: 446713
RH-Acked-by: David Howells <dhowells@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=446713

Description:
===========
If a lot of QPs fall into Error state at once and the EQ of the respective
HCA is too small, it might overrun, causing the eHCA driver to stop
processing completion events and call application software's completion
handlers, effectively causing traffic to stop.

Fix this by limiting available QPs and CQs to a customizable max count,
and determining EQ size based on these counts and a worst-case assumption.

RHEL Version Found:
================
RHEL 5.2

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1385512

Upstream Status:
================
Upstream accepted:
http://lkml.org/lkml/2008/4/29/471

Test Status:
============
Tested by forking off 20 user-space threads all doing intense network io.
Brad Peters 7/29/08

===============================================================

Brad Peters 1-978-392-1000 x 23183
IBM on-site partner.

Proposed Patch:
===============
This patch is based on 2.6.18-95.el5

diff --git a/drivers/infiniband/hw/ehca/ehca_classes.h b/drivers/infiniband/hw/ehca/ehca_classes.h
index 2cdae8b..7e725ba 100644
--- a/drivers/infiniband/hw/ehca/ehca_classes.h
+++ b/drivers/infiniband/hw/ehca/ehca_classes.h
@@ -66,6 +66,7 @@ struct ehca_av;
 #include "ehca_irq.h"
 
 #define EHCA_EQE_CACHE_SIZE 20
+#define EHCA_MAX_NUM_QUEUES 0xffff
 
 struct ehca_eqe_cache_entry {
 	struct ehca_eqe *eqe;
@@ -127,6 +128,8 @@ struct ehca_shca {
 	/* MR pgsize: bit 0-3 means 4K, 64K, 1M, 16M respectively */
 	u32 hca_cap_mr_pgsize;
 	int max_mtu;
+	atomic_t num_cqs;
+	atomic_t num_qps;
 };
 
 struct ehca_pd {
@@ -345,6 +348,8 @@ extern int ehca_use_hp_mr;
 extern int ehca_scaling_code;
 extern int ehca_lock_hcalls;
 extern int ehca_nr_ports;
+extern int ehca_max_cq;
+extern int ehca_max_qp;
 
 struct ipzu_queue_resp {
 	u32 qe_size;      /* queue entry size */
diff --git a/drivers/infiniband/hw/ehca/ehca_cq.c b/drivers/infiniband/hw/ehca/ehca_cq.c
index 0467c15..776e2d0 100644
--- a/drivers/infiniband/hw/ehca/ehca_cq.c
+++ b/drivers/infiniband/hw/ehca/ehca_cq.c
@@ -134,10 +134,19 @@ struct ib_cq *ehca_create_cq(struct ib_device *device, int cqe, int comp_vector,
 	if (cqe >= 0xFFFFFFFF - 64 - additional_cqe)
 		return ERR_PTR(-EINVAL);
 
+	if (!atomic_add_unless(&shca->num_cqs, 1, ehca_max_cq)) {
+		ehca_err(device, "Unable to create CQ, max number of %i "
+			"CQs reached.", ehca_max_cq);
+		ehca_err(device, "To increase the maximum number of CQs "
+			"use the number_of_cqs module parameter.\n");
+		return ERR_PTR(-ENOSPC);
+	}
+
 	my_cq = kmem_cache_zalloc(cq_cache, GFP_KERNEL);
 	if (!my_cq) {
 		ehca_err(device, "Out of memory for ehca_cq struct device=%p",
 			 device);
+		atomic_dec(&shca->num_cqs);
 		return ERR_PTR(-ENOMEM);
 	}
 
@@ -308,6 +317,7 @@ create_cq_exit2:
 create_cq_exit1:
 	kmem_cache_free(cq_cache, my_cq);
 
+	atomic_dec(&shca->num_cqs);
 	return cq;
 }
 
@@ -369,6 +379,7 @@ int ehca_destroy_cq(struct ib_cq *cq)
 	ipz_queue_dtor(NULL, &my_cq->ipz_queue);
 	kmem_cache_free(cq_cache, my_cq);
 
+	atomic_dec(&shca->num_cqs);
 	return 0;
 }
 
diff --git a/drivers/infiniband/hw/ehca/ehca_main.c b/drivers/infiniband/hw/ehca/ehca_main.c
index 3f5954b..b9f2b9f 100644
--- a/drivers/infiniband/hw/ehca/ehca_main.c
+++ b/drivers/infiniband/hw/ehca/ehca_main.c
@@ -68,6 +68,8 @@ int ehca_static_rate   = -1;
 int ehca_scaling_code  = 0;
 int ehca_mr_largepage  = 1;
 int ehca_lock_hcalls   = -1;
+int ehca_max_cq        = -1;
+int ehca_max_qp        = -1;
 
 module_param_named(open_aqp1,     ehca_open_aqp1,     int, S_IRUGO);
 module_param_named(debug_level,   ehca_debug_level,   int, S_IRUGO);
@@ -80,6 +82,8 @@ module_param_named(static_rate,   ehca_static_rate,   int, S_IRUGO);
 module_param_named(scaling_code,  ehca_scaling_code,  int, S_IRUGO);
 module_param_named(mr_largepage,  ehca_mr_largepage,  int, S_IRUGO);
 module_param_named(lock_hcalls,   ehca_lock_hcalls,   bool, S_IRUGO);
+module_param_named(number_of_cqs, ehca_max_cq,        int,  S_IRUGO);
+module_param_named(number_of_qps, ehca_max_qp,        int,  S_IRUGO);
 
 MODULE_PARM_DESC(open_aqp1,
 		 "AQP1 on startup (0: no (default), 1: yes)");
@@ -109,6 +113,12 @@ MODULE_PARM_DESC(mr_largepage,
 MODULE_PARM_DESC(lock_hcalls,
 		 "serialize all hCalls made by the driver "
 		 "(default: autodetect)");
+MODULE_PARM_DESC(number_of_cqs,
+		"Max number of CQs which can be allocated "
+		"(default: autodetect)");
+MODULE_PARM_DESC(number_of_qps,
+		"Max number of QPs which can be allocated "
+		"(default: autodetect)");
 
 DEFINE_RWLOCK(ehca_qp_idr_lock);
 DEFINE_RWLOCK(ehca_cq_idr_lock);
@@ -355,6 +365,25 @@ static int ehca_sense_attributes(struct ehca_shca *shca)
 				shca->hca_cap_mr_pgsize |= pgsize_map[i + 1];
 	}
 
+	/* Set maximum number of CQs and QPs to calculate EQ size */
+	if (ehca_max_qp == -1)
+		ehca_max_qp = min_t(int, rblock->max_qp, EHCA_MAX_NUM_QUEUES);
+	else if (ehca_max_qp < 1 || ehca_max_qp > rblock->max_qp) {
+		ehca_gen_err("Requested number of QPs is out of range (1 - %i) "
+			"specified by HW", rblock->max_qp);
+		ret = -EINVAL;
+		goto sense_attributes1;
+	}
+
+	if (ehca_max_cq == -1)
+		ehca_max_cq = min_t(int, rblock->max_cq, EHCA_MAX_NUM_QUEUES);
+	else if (ehca_max_cq < 1 || ehca_max_cq > rblock->max_cq) {
+		ehca_gen_err("Requested number of CQs is out of range (1 - %i) "
+			"specified by HW", rblock->max_cq);
+		ret = -EINVAL;
+		goto sense_attributes1;
+	}
+
 	/* query max MTU from first port -- it's the same for all ports */
 	port = (struct hipz_query_port *)rblock;
 	h_ret = hipz_h_query_port(shca->ipz_hca_handle, 1, port);
@@ -689,7 +718,7 @@ static int __devinit ehca_probe(struct ibmebus_dev *dev,
 	struct ehca_shca *shca;
 	const u64 *handle;
 	struct ib_pd *ibpd;
-	int ret, i;
+	int ret, i, eq_size;
 
 	handle = of_get_property(dev->ofdev.node, "ibm,hca-handle", NULL);
 	if (!handle) {
@@ -710,6 +739,8 @@ static int __devinit ehca_probe(struct ibmebus_dev *dev,
 		return -ENOMEM;
 	}
 	mutex_init(&shca->modify_mutex);
+	atomic_set(&shca->num_cqs, 0);
+	atomic_set(&shca->num_qps, 0);
 	for (i = 0; i < ARRAY_SIZE(shca->sport); i++)
 		spin_lock_init(&shca->sport[i].mod_sqp_lock);
 
@@ -729,8 +760,9 @@ static int __devinit ehca_probe(struct ibmebus_dev *dev,
 		goto probe1;
 	}
 
+	eq_size = 2 * ehca_max_cq + 4 * ehca_max_qp;
 	/* create event queues */
-	ret = ehca_create_eq(shca, &shca->eq, EHCA_EQ, 2048);
+	ret = ehca_create_eq(shca, &shca->eq, EHCA_EQ, eq_size);
 	if (ret) {
 		ehca_err(&shca->ib_device, "Cannot create EQ.");
 		goto probe1;
diff --git a/drivers/infiniband/hw/ehca/ehca_qp.c b/drivers/infiniband/hw/ehca/ehca_qp.c
index 1012f15..162ce6f 100644
--- a/drivers/infiniband/hw/ehca/ehca_qp.c
+++ b/drivers/infiniband/hw/ehca/ehca_qp.c
@@ -424,6 +424,14 @@ static struct ehca_qp *internal_create_qp(
 	u32 swqe_size = 0, rwqe_size = 0, ib_qp_num;
 	unsigned long flags;
 
+	if (!atomic_add_unless(&shca->num_qps, 1, ehca_max_qp)) {
+		ehca_err(pd->device, "Unable to create QP, max number of %i "
+			 "QPs reached.", ehca_max_qp);
+		ehca_err(pd->device, "To increase the maximum number of QPs "
+			 "use the number_of_qps module parameter.\n");
+		return ERR_PTR(-ENOSPC);
+	}
+
 	memset(&parms, 0, sizeof(parms));
 	qp_type = init_attr->qp_type;
 
@@ -431,6 +439,7 @@ static struct ehca_qp *internal_create_qp(
 		init_attr->sq_sig_type != IB_SIGNAL_ALL_WR) {
 		ehca_err(pd->device, "init_attr->sg_sig_type=%x not allowed",
 			 init_attr->sq_sig_type);
+		atomic_dec(&shca->num_qps);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -455,6 +464,7 @@ static struct ehca_qp *internal_create_qp(
 
 	if (is_llqp && has_srq) {
 		ehca_err(pd->device, "LLQPs can't have an SRQ");
+		atomic_dec(&shca->num_qps);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -466,6 +476,7 @@ static struct ehca_qp *internal_create_qp(
 			ehca_err(pd->device, "no more than three SGEs "
 				 "supported for SRQ  pd=%p  max_sge=%x",
 				 pd, init_attr->cap.max_recv_sge);
+			atomic_dec(&shca->num_qps);
 			return ERR_PTR(-EINVAL);
 		}
 	}
@@ -477,6 +488,7 @@ static struct ehca_qp *internal_create_qp(
 	    qp_type != IB_QPT_SMI &&
 	    qp_type != IB_QPT_GSI) {
 		ehca_err(pd->device, "wrong QP Type=%x", qp_type);
+		atomic_dec(&shca->num_qps);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -490,6 +502,7 @@ static struct ehca_qp *internal_create_qp(
 					 "or max_rq_wr=%x for RC LLQP",
 					 init_attr->cap.max_send_wr,
 					 init_attr->cap.max_recv_wr);
+				atomic_dec(&shca->num_qps);
 				return ERR_PTR(-EINVAL);
 			}
 			break;
@@ -497,6 +510,7 @@ static struct ehca_qp *internal_create_qp(
 			if (!EHCA_BMASK_GET(HCA_CAP_UD_LL_QP, shca->hca_cap)) {
 				ehca_err(pd->device, "UD LLQP not supported "
 					 "by this adapter");
+				atomic_dec(&shca->num_qps);
 				return ERR_PTR(-ENOSYS);
 			}
 			if (!(init_attr->cap.max_send_sge <= 5
@@ -508,20 +522,22 @@ static struct ehca_qp *internal_create_qp(
 					 "or max_recv_sge=%x for UD LLQP",
 					 init_attr->cap.max_send_sge,
 					 init_attr->cap.max_recv_sge);
+				atomic_dec(&shca->num_qps);
 				return ERR_PTR(-EINVAL);
 			} else if (init_attr->cap.max_send_wr > 255) {
 				ehca_err(pd->device,
 					 "Invalid Number of "
 					 "max_send_wr=%x for UD QP_TYPE=%x",
 					 init_attr->cap.max_send_wr, qp_type);
+				atomic_dec(&shca->num_qps);
 				return ERR_PTR(-EINVAL);
 			}
 			break;
 		default:
 			ehca_err(pd->device, "unsupported LL QP Type=%x",
 				 qp_type);
+			atomic_dec(&shca->num_qps);
 			return ERR_PTR(-EINVAL);
-			break;
 		}
 	} else {
 		int max_sge = (qp_type == IB_QPT_UD || qp_type == IB_QPT_SMI
@@ -533,6 +549,7 @@ static struct ehca_qp *internal_create_qp(
 				 "send_sge=%x recv_sge=%x max_sge=%x",
 				 init_attr->cap.max_send_sge,
 				 init_attr->cap.max_recv_sge, max_sge);
+			atomic_dec(&shca->num_qps);
 			return ERR_PTR(-EINVAL);
 		}
 	}
@@ -543,6 +560,7 @@ static struct ehca_qp *internal_create_qp(
 	my_qp = kmem_cache_zalloc(qp_cache, GFP_KERNEL);
 	if (!my_qp) {
 		ehca_err(pd->device, "pd=%p not enough memory to alloc qp", pd);
+		atomic_dec(&shca->num_qps);
 		return ERR_PTR(-ENOMEM);
 	}
 
@@ -822,6 +840,7 @@ create_qp_exit1:
 
 create_qp_exit0:
 	kmem_cache_free(qp_cache, my_qp);
+	atomic_dec(&shca->num_qps);
 	return ERR_PTR(ret);
 }
 
@@ -1990,6 +2009,7 @@ static int internal_destroy_qp(struct ib_device *dev, struct ehca_qp *my_qp,
 	if (HAS_SQ(my_qp))
 		ipz_queue_dtor(my_pd, &my_qp->ipz_squeue);
 	kmem_cache_free(qp_cache, my_qp);
+	atomic_dec(&shca->num_qps);
 	return 0;
 }