The struct rdma_id_private contains three bit-fields, tos_set,
timeout_set, and min_rnr_timer_set. These are set by accessor
functions without any synchronization. If two or all accessor
functions are invoked in close proximity in time, there will be
Read-Modify-Write from several contexts to the same variable, and the
result will be intermittent.
Replace with a flag variable and a function for set with appropriate
memory barriers and the use of test_bit().
Signed-off-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
Signed-off-by: Hans Westgaard Ry<hans.westgaard.ry@xxxxxxxxxx>
---
v1 -> v2:
* Removed define wizardry and replaced with a set function
with memory barriers. Suggested by Leon.
* Removed zero-initialization of flags, due to kzalloc(),
as suggested by Leon
* Review comments from Stefan implicitly adapted due to
first bullet above
* Moved defines and inline function from header file to
cma.c, as suggested by the undersigned
* Renamed enum to cm_id_priv_flag_bits as suggested by the
undersigned
v2 -> v3:
* Fixed lines longer than 80 chars
* s/an inline function/a function/ in commit message
---
drivers/infiniband/core/cma.c | 42 ++++++++++++++++++++++++++------------
drivers/infiniband/core/cma_priv.h | 4 +---
2 files changed, 30 insertions(+), 16 deletions(-)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 2b9ffc2..6759889 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -48,6 +48,21 @@
#define CMA_IBOE_PACKET_LIFETIME 18
#define CMA_PREFERRED_ROCE_GID_TYPE IB_GID_TYPE_ROCE_UDP_ENCAP
+static void set_bit_mb(unsigned long nr, unsigned long *flags)
+{
+ /* set_bit() does not imply a memory barrier */
+ smp_mb__before_atomic();
+ set_bit(nr, flags);
+ /* set_bit() does not imply a memory barrier */
+ smp_mb__after_atomic();
+}
+
+enum cm_id_priv_flag_bits {
+ TOS_SET,
+ TIMEOUT_SET,
+ MIN_RNR_TIMER_SET,
+};
+
static const char * const cma_events[] = {
[RDMA_CM_EVENT_ADDR_RESOLVED] = "address resolved",
[RDMA_CM_EVENT_ADDR_ERROR] = "address error",
@@ -844,9 +859,6 @@ static void cma_id_put(struct rdma_id_private *id_priv)
id_priv->id.event_handler = event_handler;
id_priv->id.ps = ps;
id_priv->id.qp_type = qp_type;
- id_priv->tos_set = false;
- id_priv->timeout_set = false;
- id_priv->min_rnr_timer_set = false;
id_priv->gid_type = IB_GID_TYPE_IB;
spin_lock_init(&id_priv->lock);
mutex_init(&id_priv->qp_mutex);
@@ -1134,10 +1146,12 @@ int rdma_init_qp_attr(struct rdma_cm_id *id, struct ib_qp_attr *qp_attr,
ret = -ENOSYS;
}
- if ((*qp_attr_mask & IB_QP_TIMEOUT) && id_priv->timeout_set)
+ if ((*qp_attr_mask & IB_QP_TIMEOUT) &&
+ test_bit(TIMEOUT_SET, &id_priv->flags))
qp_attr->timeout = id_priv->timeout;
- if ((*qp_attr_mask & IB_QP_MIN_RNR_TIMER) && id_priv->min_rnr_timer_set)
+ if ((*qp_attr_mask & IB_QP_MIN_RNR_TIMER) &&
+ test_bit(MIN_RNR_TIMER_SET, &id_priv->flags))
qp_attr->min_rnr_timer = id_priv->min_rnr_timer;
return ret;
@@ -2472,7 +2486,7 @@ static int cma_iw_listen(struct rdma_id_private *id_priv, int backlog)
return PTR_ERR(id);
id->tos = id_priv->tos;
- id->tos_set = id_priv->tos_set;
+ id->tos_set = test_bit(TOS_SET, &id_priv->flags);
id->afonly = id_priv->afonly;
id_priv->cm_id.iw = id;
@@ -2533,7 +2547,7 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv,
cma_id_get(id_priv);
dev_id_priv->internal_id = 1;
dev_id_priv->afonly = id_priv->afonly;
- dev_id_priv->tos_set = id_priv->tos_set;
+ dev_id_priv->flags = id_priv->flags;
dev_id_priv->tos = id_priv->tos;
ret = rdma_listen(&dev_id_priv->id, id_priv->backlog);
@@ -2582,7 +2596,7 @@ void rdma_set_service_type(struct rdma_cm_id *id, int tos)
id_priv = container_of(id, struct rdma_id_private, id);
id_priv->tos = (u8) tos;
- id_priv->tos_set = true;
+ set_bit_mb(TOS_SET, &id_priv->flags);
}
EXPORT_SYMBOL(rdma_set_service_type);
@@ -2610,7 +2624,7 @@ int rdma_set_ack_timeout(struct rdma_cm_id *id, u8 timeout)
id_priv = container_of(id, struct rdma_id_private, id);
id_priv->timeout = timeout;
- id_priv->timeout_set = true;
+ set_bit_mb(TIMEOUT_SET, &id_priv->flags);
return 0;
}
@@ -2647,7 +2661,7 @@ int rdma_set_min_rnr_timer(struct rdma_cm_id *id, u8 min_rnr_timer)
id_priv = container_of(id, struct rdma_id_private, id);
id_priv->min_rnr_timer = min_rnr_timer;
- id_priv->min_rnr_timer_set = true;
+ set_bit_mb(MIN_RNR_TIMER_SET, &id_priv->flags);
return 0;
}
@@ -3033,7 +3047,8 @@ static int cma_resolve_iboe_route(struct rdma_id_private *id_priv)
u8 default_roce_tos = id_priv->cma_dev->default_roce_tos[id_priv->id.port_num -
rdma_start_port(id_priv->cma_dev->device)];
- u8 tos = id_priv->tos_set ? id_priv->tos : default_roce_tos;
+ u8 tos = test_bit(TOS_SET, &id_priv->flags) ?
+ id_priv->tos : default_roce_tos;
work = kzalloc(sizeof *work, GFP_KERNEL);
@@ -3081,7 +3096,8 @@ static int cma_resolve_iboe_route(struct rdma_id_private *id_priv)
* PacketLifeTime = local ACK timeout/2
* as a reasonable approximation for RoCE networks.
*/
- route->path_rec->packet_life_time = id_priv->timeout_set ?
+ route->path_rec->packet_life_time =
+ test_bit(TIMEOUT_SET, &id_priv->flags) ?
id_priv->timeout - 1 : CMA_IBOE_PACKET_LIFETIME;
if (!route->path_rec->mtu) {
@@ -4107,7 +4123,7 @@ static int cma_connect_iw(struct rdma_id_private *id_priv,
return PTR_ERR(cm_id);
cm_id->tos = id_priv->tos;
- cm_id->tos_set = id_priv->tos_set;
+ cm_id->tos_set = test_bit(TOS_SET, &id_priv->flags);
id_priv->cm_id.iw = cm_id;
memcpy(&cm_id->local_addr, cma_src_addr(id_priv),
diff --git a/drivers/infiniband/core/cma_priv.h b/drivers/infiniband/core/cma_priv.h
index 5c463da..5d3d0db 100644
--- a/drivers/infiniband/core/cma_priv.h
+++ b/drivers/infiniband/core/cma_priv.h
@@ -82,11 +82,9 @@ struct rdma_id_private {
u32 qkey;
u32 qp_num;
u32 options;
+ unsigned long flags;
u8 srq;
u8 tos;
- u8 tos_set:1;
- u8 timeout_set:1;
- u8 min_rnr_timer_set:1;
u8 reuseaddr;
u8 afonly;
u8 timeout;
--
1.8.3.1
