From 7286d223198123e8530fc9c91a898f7a5529256d Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Thu, 6 Aug 2009 10:05:10 +0000
Subject: [PATCH] Fixed data races on manipulation of the srpt_devices list by
 eliminating this list. Only the number of IB devices is relevant for the SRPT
 implementation. Introduced a new counter that tracks the number of IB
 devices.

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@1016 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 srpt/src/ib_srpt.c | 20 +++++++-------------
 srpt/src/ib_srpt.h |  2 --
 2 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/srpt/src/ib_srpt.c b/srpt/src/ib_srpt.c
index bf0493d26..ee0cdceba 100644
--- a/srpt/src/ib_srpt.c
+++ b/srpt/src/ib_srpt.c
@@ -84,7 +84,7 @@ struct srpt_thread {
 
 static u64 mellanox_ioc_guid;
 /* List of srpt_device structures. */
-static struct list_head srpt_devices;
+static atomic_t srpt_device_count;
 static int thread;
 static struct srpt_thread srpt_thread;
 static DECLARE_WAIT_QUEUE_HEAD(ioctx_list_waitQ);
@@ -2345,17 +2345,15 @@ static void srpt_refresh_port_work(struct work_struct *work)
  */
 static int srpt_detect(struct scst_tgt_template *tp)
 {
-	struct srpt_device *sdev;
-	int count = 0;
+	int device_count;
 
 	TRACE_ENTRY();
 
-	list_for_each_entry(sdev, &srpt_devices, list)
-		++count;
+	device_count = atomic_read(&srpt_device_count);
 
-	TRACE_EXIT();
+	TRACE_EXIT_RES(device_count);
 
-	return count;
+	return device_count;
 }
 
 /*
@@ -2681,8 +2679,6 @@ static void srpt_add_one(struct ib_device *device)
 	for (i = 0; i < SRPT_SRQ_SIZE; ++i)
 		srpt_post_recv(sdev, sdev->ioctx_ring[i]);
 
-	list_add_tail(&sdev->list, &srpt_devices);
-
 	ib_set_client_data(device, &srpt_client, sdev);
 
 	sdev->scst_tgt = scst_register(&srpt_template, NULL);
@@ -2714,6 +2710,8 @@ static void srpt_add_one(struct ib_device *device)
 		}
 	}
 
+	atomic_inc(&srpt_device_count);
+
 	TRACE_EXIT();
 
 	return;
@@ -2722,7 +2720,6 @@ err_refresh_port:
 	scst_unregister(sdev->scst_tgt);
 err_ring:
 	ib_set_client_data(device, &srpt_client, NULL);
-	list_del(&sdev->list);
 	srpt_free_ioctx_ring(sdev);
 err_event:
 	ib_unregister_event_handler(&sdev->event_handler);
@@ -2799,7 +2796,6 @@ static void srpt_remove_one(struct ib_device *device)
 #endif
 
 	srpt_free_ioctx_ring(sdev);
-	list_del(&sdev->list);
 	kfree(sdev);
 
 	TRACE_EXIT();
@@ -2859,8 +2855,6 @@ static int __init srpt_init_module(void)
 {
 	int ret;
 
-	INIT_LIST_HEAD(&srpt_devices);
-
 	ret = class_register(&srpt_class);
 	if (ret) {
 		printk(KERN_ERR PFX "couldn't register class ib_srpt\n");
diff --git a/srpt/src/ib_srpt.h b/srpt/src/ib_srpt.h
index 3ce7ddaa4..3f6253ba7 100644
--- a/srpt/src/ib_srpt.h
+++ b/srpt/src/ib_srpt.h
@@ -198,8 +198,6 @@ struct srpt_device {
 	 */
 	struct ib_device_attr dev_attr;
 	struct srpt_ioctx *ioctx_ring[SRPT_SRQ_SIZE];
-	/* List node for insertion in the srpt_devices list. */
-	struct list_head list;
 	/*
 	 * List node for insertion in the srpt_rdma_ch::list list.
 	 * This list is protected by srpt_device::spinlock.