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Message-ID: <20180607190832.GA24370@bombadil.infradead.org>
Date: Thu, 7 Jun 2018 12:08:32 -0700
From: Matthew Wilcox <willy@...radead.org>
To: hans.westgaard.ry@...cle.com, Doug Ledford <dledford@...hat.com>,
Jason Gunthorpe <jgg@...lanox.com>, linux-rdma@...r.kernel.org,
Håkon Bugge <haakon.bugge@...cle.com>,
Parav Pandit <parav@...lanox.com>,
Jack Morgenstein <jackm@....mellanox.co.il>,
Pravin Shedge <pravin.shedge4linux@...il.com>,
linux-kernel@...r.kernel.org
Subject: [RFC] IB/mad: Use IDR instead of per-port list
Hans reports a bug where the mlx4 driver uses the MSB of the agent number
to store slave number, meaning we can only use agent numbers up to 2^24.
Fix this by using an IDR to assign the agent numbers and also look up the
agent when a MSD packet is received.
I've changed the locking substantially, so this may well have a
performance issue. There are a few different possibilities for fixing
that, including moving to an RCU-based lookup.
diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index b28452a55a08..611a1f268b07 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -38,6 +38,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/dma-mapping.h>
+#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/security.h>
@@ -58,8 +59,8 @@ MODULE_PARM_DESC(send_queue_size, "Size of send queue in number of work requests
module_param_named(recv_queue_size, mad_recvq_size, int, 0444);
MODULE_PARM_DESC(recv_queue_size, "Size of receive queue in number of work requests");
+static DEFINE_IDR(ib_mad_clients);
static struct list_head ib_mad_port_list;
-static atomic_t ib_mad_client_id = ATOMIC_INIT(0);
/* Port list lock */
static DEFINE_SPINLOCK(ib_mad_port_list_lock);
@@ -376,8 +377,16 @@ struct ib_mad_agent *ib_register_mad_agent(struct ib_device *device,
goto error4;
}
- spin_lock_irqsave(&port_priv->reg_lock, flags);
- mad_agent_priv->agent.hi_tid = atomic_inc_return(&ib_mad_client_id);
+ idr_preload(GFP_KERNEL);
+ idr_lock_irqsave(&ib_mad_clients, flags);
+
+ ret2 = idr_alloc_cyclic(&ib_mad_clients, mad_agent_priv, 0,
+ (1 << 24), GFP_ATOMIC);
+ if (ret2 < 0) {
+ ret = ERR_PTR(ret2);
+ goto error5;
+ }
+ mad_agent_priv->agent.hi_tid = ret2;
/*
* Make sure MAD registration (if supplied)
@@ -393,7 +402,7 @@ struct ib_mad_agent *ib_register_mad_agent(struct ib_device *device,
if (method) {
if (method_in_use(&method,
mad_reg_req))
- goto error5;
+ goto error6;
}
}
ret2 = add_nonoui_reg_req(mad_reg_req, mad_agent_priv,
@@ -409,24 +418,26 @@ struct ib_mad_agent *ib_register_mad_agent(struct ib_device *device,
if (is_vendor_method_in_use(
vendor_class,
mad_reg_req))
- goto error5;
+ goto error6;
}
}
ret2 = add_oui_reg_req(mad_reg_req, mad_agent_priv);
}
if (ret2) {
ret = ERR_PTR(ret2);
- goto error5;
+ goto error6;
}
}
- /* Add mad agent into port's agent list */
- list_add_tail(&mad_agent_priv->agent_list, &port_priv->agent_list);
- spin_unlock_irqrestore(&port_priv->reg_lock, flags);
+ idr_unlock_irqrestore(&ib_mad_clients, flags);
+ idr_preload_end();
return &mad_agent_priv->agent;
+error6:
+ idr_remove(&ib_mad_clients, mad_agent_priv->agent.hi_tid);
error5:
- spin_unlock_irqrestore(&port_priv->reg_lock, flags);
+ idr_unlock_irqrestore(&ib_mad_clients, flags);
+ idr_preload_end();
ib_mad_agent_security_cleanup(&mad_agent_priv->agent);
error4:
kfree(reg_req);
@@ -587,10 +598,10 @@ static void unregister_mad_agent(struct ib_mad_agent_private *mad_agent_priv)
port_priv = mad_agent_priv->qp_info->port_priv;
cancel_delayed_work(&mad_agent_priv->timed_work);
- spin_lock_irqsave(&port_priv->reg_lock, flags);
+ idr_lock_irqsave(&ib_mad_clients, flags);
remove_mad_reg_req(mad_agent_priv);
- list_del(&mad_agent_priv->agent_list);
- spin_unlock_irqrestore(&port_priv->reg_lock, flags);
+ idr_remove(&ib_mad_clients, mad_agent_priv->agent.hi_tid);
+ idr_unlock_irqrestore(&ib_mad_clients, flags);
flush_workqueue(port_priv->wq);
ib_cancel_rmpp_recvs(mad_agent_priv);
@@ -1718,22 +1729,16 @@ find_mad_agent(struct ib_mad_port_private *port_priv,
struct ib_mad_agent_private *mad_agent = NULL;
unsigned long flags;
- spin_lock_irqsave(&port_priv->reg_lock, flags);
+ idr_lock_irqsave(&ib_mad_clients, flags);
if (ib_response_mad(mad_hdr)) {
u32 hi_tid;
- struct ib_mad_agent_private *entry;
/*
* Routing is based on high 32 bits of transaction ID
* of MAD.
*/
hi_tid = be64_to_cpu(mad_hdr->tid) >> 32;
- list_for_each_entry(entry, &port_priv->agent_list, agent_list) {
- if (entry->agent.hi_tid == hi_tid) {
- mad_agent = entry;
- break;
- }
- }
+ mad_agent = idr_find(&ib_mad_clients, hi_tid);
} else {
struct ib_mad_mgmt_class_table *class;
struct ib_mad_mgmt_method_table *method;
@@ -1794,7 +1799,7 @@ find_mad_agent(struct ib_mad_port_private *port_priv,
}
}
out:
- spin_unlock_irqrestore(&port_priv->reg_lock, flags);
+ idr_unlock_irqrestore(&ib_mad_clients, flags);
return mad_agent;
}
@@ -3156,8 +3161,6 @@ static int ib_mad_port_open(struct ib_device *device,
port_priv->device = device;
port_priv->port_num = port_num;
- spin_lock_init(&port_priv->reg_lock);
- INIT_LIST_HEAD(&port_priv->agent_list);
init_mad_qp(port_priv, &port_priv->qp_info[0]);
init_mad_qp(port_priv, &port_priv->qp_info[1]);
@@ -3336,6 +3339,9 @@ int ib_mad_init(void)
INIT_LIST_HEAD(&ib_mad_port_list);
+ /* Client ID 0 is used for snoop-only clients */
+ idr_alloc(&ib_mad_clients, NULL, 0, 0, GFP_KERNEL);
+
if (ib_register_client(&mad_client)) {
pr_err("Couldn't register ib_mad client\n");
return -EINVAL;
diff --git a/drivers/infiniband/core/mad_priv.h b/drivers/infiniband/core/mad_priv.h
index 28669f6419e1..f2cb2eea7d42 100644
--- a/drivers/infiniband/core/mad_priv.h
+++ b/drivers/infiniband/core/mad_priv.h
@@ -89,7 +89,6 @@ struct ib_rmpp_segment {
};
struct ib_mad_agent_private {
- struct list_head agent_list;
struct ib_mad_agent agent;
struct ib_mad_reg_req *reg_req;
struct ib_mad_qp_info *qp_info;
@@ -201,9 +200,7 @@ struct ib_mad_port_private {
struct ib_cq *cq;
struct ib_pd *pd;
- spinlock_t reg_lock;
struct ib_mad_mgmt_version_table version[MAX_MGMT_VERSION];
- struct list_head agent_list;
struct workqueue_struct *wq;
struct ib_mad_qp_info qp_info[IB_MAD_QPS_CORE];
};
diff --git a/include/linux/idr.h b/include/linux/idr.h
index e856f4e0ab35..97b4924f0bca 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -81,6 +81,11 @@ static inline void idr_set_cursor(struct idr *idr, unsigned int val)
WRITE_ONCE(idr->idr_next, val);
}
+#define idr_lock_irqsave(idr, flags) \
+ xa_lock_irqsave(&(idr)->idr_rt, flags)
+#define idr_unlock_irqrestore(idr, flags) \
+ xa_unlock_irqrestore(&(idr)->idr_rt, flags)
+
/**
* DOC: idr sync
* idr synchronization (stolen from radix-tree.h)
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