From: Håkon Bugge <Haakon.Bugge@oracle.com>
Date: Fri, 7 Jul 2017 10:33:30 +0000 (+0200)
Subject: net/rds: Add mutex exclusion for vector_load
X-Git-Tag: v4.1.12-106.0.20170710_2300~15
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7abc664d380e764930270966a91fd19bcae87e3e;p=users%2Fjedix%2Flinux-maple.git

net/rds: Add mutex exclusion for vector_load

Several TOS connections may invoke ibdev_get_unused_vector()
concurrently. Hence, mutual exclusion is required to protect
rds_ibdev->vector_load.

Changes from v1:
   - Reworded commit message and commentary based on Avinash's feedback
   - Added r-b from Wei Lin and Avinash

Orabug: 26406492

Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Wei Lin Guay <wei.lin.guay@oracle.com>
Reviewed-by: Avinash Repaka <avinash.repaka@oracle.com>
---

diff --git a/net/rds/ib.c b/net/rds/ib.c
index 93425b800dfb..35dac3bfee74 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -2052,6 +2052,7 @@ void rds_ib_add_one(struct ib_device *device)
 		printk(KERN_ERR "RDS/IB: failed to allocate vector memoru\n");
 		goto put_dev;
 	}
+	mutex_init(&rds_ibdev->vector_load_lock);
 
 	rds_ibdev->mr = ib_get_dma_mr(rds_ibdev->pd, IB_ACCESS_LOCAL_WRITE);
 	if (IS_ERR(rds_ibdev->mr)) {
diff --git a/net/rds/ib.h b/net/rds/ib.h
index fd705edac6a7..f595f358d8d7 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -431,6 +431,10 @@ struct rds_ib_device {
 	struct rds_ib_port      *ports;
 	struct ib_event_handler event_handler;
 	int			*vector_load;
+	/* Several TOS connections may invoke ibdev_get_unused_vector()
+	 * concurrently, hence we need protection for vector_load
+	 */
+	struct mutex		vector_load_lock;
 
 	/* flag indicating ib_device is under freeing up or is freed up to make
 	 * the race between rds_ib_remove_one() and rds_release() safe.
diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index a217d978c894..98c14c6e2aa8 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -599,10 +599,14 @@ static void rds_ib_qp_event_handler(struct ib_event *event, void *data)
 
 static inline int ibdev_get_unused_vector(struct rds_ib_device *rds_ibdev)
 {
-	int min = rds_ibdev->vector_load[rds_ibdev->dev->num_comp_vectors - 1];
-	int index = rds_ibdev->dev->num_comp_vectors - 1;
+	int index;
+	int min;
 	int i;
 
+	mutex_lock(&rds_ibdev->vector_load_lock);
+	min = rds_ibdev->vector_load[rds_ibdev->dev->num_comp_vectors - 1];
+	index = rds_ibdev->dev->num_comp_vectors - 1;
+
 	for (i = rds_ibdev->dev->num_comp_vectors - 1; i >= 0; i--) {
 		if (rds_ibdev->vector_load[i] < min) {
 			index = i;
@@ -611,12 +615,16 @@ static inline int ibdev_get_unused_vector(struct rds_ib_device *rds_ibdev)
 	}
 
 	rds_ibdev->vector_load[index]++;
+	mutex_unlock(&rds_ibdev->vector_load_lock);
+
 	return index;
 }
 
 static inline void ibdev_put_vector(struct rds_ib_device *rds_ibdev, int index)
 {
+	mutex_lock(&rds_ibdev->vector_load_lock);
 	rds_ibdev->vector_load[index]--;
+	mutex_unlock(&rds_ibdev->vector_load_lock);
 }
 
 /*