IB/core: Protect against concurrent access to hardware stats

Currently access to hardware stats buffer isn't protected, this can
result in multiple writes and reads at the same time to the same
memory location. This can lead to providing an incorrect value to
the user. Add a mutex to protect against it.

Fixes: b40f4757daa1 ("IB/core: Make device counter infrastructure dynamic")
Signed-off-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 28 insertions, 6 deletions

diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
index cf36ff1f0068..9b0fbab41dc6 100644
--- a/drivers/infiniband/core/sysfs.c
+++ b/drivers/infiniband/core/sysfs.c
@@ -811,10 +811,15 @@ static ssize_t show_hw_stats(struct kobject *kobj, struct attribute *attr,
 		dev = port->ibdev;
 		stats = port->hw_stats;
 	}
+	mutex_lock(&stats->lock);
 	ret = update_hw_stats(dev, stats, hsa->port_num, hsa->index);
 	if (ret)
-		return ret;
-	return print_hw_stat(stats, hsa->index, buf);
+		goto unlock;
+	ret = print_hw_stat(stats, hsa->index, buf);
+unlock:
+	mutex_unlock(&stats->lock);
+
+	return ret;
 }
 
 static ssize_t show_stats_lifespan(struct kobject *kobj,
@@ -822,17 +827,25 @@ static ssize_t show_stats_lifespan(struct kobject *kobj,
 				   char *buf)
 {
 	struct hw_stats_attribute *hsa;
+	struct rdma_hw_stats *stats;
 	int msecs;
 
 	hsa = container_of(attr, struct hw_stats_attribute, attr);
 	if (!hsa->port_num) {
 		struct ib_device *dev = container_of((struct device *)kobj,
 						     struct ib_device, dev);
-		msecs = jiffies_to_msecs(dev->hw_stats->lifespan);
+
+		stats = dev->hw_stats;
 	} else {
 		struct ib_port *p = container_of(kobj, struct ib_port, kobj);
-		msecs = jiffies_to_msecs(p->hw_stats->lifespan);
+
+		stats = p->hw_stats;
 	}
+
+	mutex_lock(&stats->lock);
+	msecs = jiffies_to_msecs(stats->lifespan);
+	mutex_unlock(&stats->lock);
+
 	return sprintf(buf, "%d\n", msecs);
 }
 
@@ -841,6 +854,7 @@ static ssize_t set_stats_lifespan(struct kobject *kobj,
 				  const char *buf, size_t count)
 {
 	struct hw_stats_attribute *hsa;
+	struct rdma_hw_stats *stats;
 	int msecs;
 	int jiffies;
 	int ret;
@@ -855,11 +869,18 @@ static ssize_t set_stats_lifespan(struct kobject *kobj,
 	if (!hsa->port_num) {
 		struct ib_device *dev = container_of((struct device *)kobj,
 						     struct ib_device, dev);
-		dev->hw_stats->lifespan = jiffies;
+
+		stats = dev->hw_stats;
 	} else {
 		struct ib_port *p = container_of(kobj, struct ib_port, kobj);
-		p->hw_stats->lifespan = jiffies;
+
+		stats = p->hw_stats;
 	}
+
+	mutex_lock(&stats->lock);
+	stats->lifespan = jiffies;
+	mutex_unlock(&stats->lock);
+
 	return count;
 }
 
@@ -952,6 +973,7 @@ static void setup_hw_stats(struct ib_device *device, struct ib_port *port,
 		sysfs_attr_init(hsag->attrs[i]);
 	}
 
+	mutex_init(&stats->lock);
 	/* treat an error here as non-fatal */
 	hsag->attrs[i] = alloc_hsa_lifespan("lifespan", port_num);
 	if (hsag->attrs[i])