RDMA/counter: Add PID category support in auto mode

With the "PID" category QPs have same PID will be bound to same counter;
If this category is not set then QPs have different PIDs will be bound
to same counter.

This is implemented for 2 reasons:
1. The counter is a limited resource, while there may be dozens of
   applications, each of which creates several types of QPs, which means
   it may doesn't have enough counter.
2. The system administrator needs all QPs created by all applications
   with same type bound to one counter.

The counter name and PID is only make sense when "PID" category are
configured.

This category can also be used in combine with others, e.g. QP type.

Link: https://lore.kernel.org/r/20200702082933.424537-2-leon@kernel.org
Signed-off-by: Mark Zhang <markz@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/counters.c

@@ -8,7 +8,7 @@
 #include "core_priv.h"
 #include "restrack.h"
 
-#define ALL_AUTO_MODE_MASKS (RDMA_COUNTER_MASK_QP_TYPE)
+#define ALL_AUTO_MODE_MASKS (RDMA_COUNTER_MASK_QP_TYPE | RDMA_COUNTER_MASK_PID)
 
 static int __counter_set_mode(struct rdma_counter_mode *curr,
 			      enum rdma_nl_counter_mode new_mode,
@@ -149,23 +149,13 @@ static bool auto_mode_match(struct ib_qp *qp, struct rdma_counter *counter,
 	struct auto_mode_param *param = &counter->mode.param;
 	bool match = true;
 
-	/*
-	 * Ensure that counter belongs to the right PID.  This operation can
-	 * race with user space which kills the process and leaves QP and
-	 * counters orphans.
-	 *
-	 * It is not a big deal because exitted task will leave both QP and
-	 * counter in the same bucket of zombie process. Just ensure that
-	 * process is still alive before procedding.
-	 *
-	 */
-	if (task_pid_nr(counter->res.task) != task_pid_nr(qp->res.task) ||
-	    !task_pid_nr(qp->res.task))
-		return false;
-
 	if (auto_mask & RDMA_COUNTER_MASK_QP_TYPE)
 		match &= (param->qp_type == qp->qp_type);
 
+	if (auto_mask & RDMA_COUNTER_MASK_PID)
+		match &= (task_pid_nr(counter->res.task) ==
+			  task_pid_nr(qp->res.task));
+
 	return match;
 }
 

drivers/infiniband/core/nldev.c

@@ -711,11 +711,16 @@ static int fill_stat_counter_mode(struct sk_buff *msg,
 	if (nla_put_u32(msg, RDMA_NLDEV_ATTR_STAT_MODE, m->mode))
 		return -EMSGSIZE;
 
-	if (m->mode == RDMA_COUNTER_MODE_AUTO)
+	if (m->mode == RDMA_COUNTER_MODE_AUTO) {
 		if ((m->mask & RDMA_COUNTER_MASK_QP_TYPE) &&
 		    nla_put_u8(msg, RDMA_NLDEV_ATTR_RES_TYPE, m->param.qp_type))
 			return -EMSGSIZE;
 
+		if ((m->mask & RDMA_COUNTER_MASK_PID) &&
+		    fill_res_name_pid(msg, &counter->res))
+			return -EMSGSIZE;
+	}
+
 	return 0;
 }
 
@@ -855,7 +860,6 @@ static int fill_res_counter_entry(struct sk_buff *msg, bool has_cap_net_admin,
 
 	if (nla_put_u32(msg, RDMA_NLDEV_ATTR_PORT_INDEX, counter->port) ||
 	    nla_put_u32(msg, RDMA_NLDEV_ATTR_STAT_COUNTER_ID, counter->id) ||
-	    fill_res_name_pid(msg, &counter->res) ||
 	    fill_stat_counter_mode(msg, counter) ||
 	    fill_stat_counter_qps(msg, counter) ||
 	    fill_stat_counter_hwcounters(msg, counter))

include/uapi/rdma/rdma_netlink.h

@@ -569,5 +569,6 @@ enum rdma_nl_counter_mode {
  */
 enum rdma_nl_counter_mask {
 	RDMA_COUNTER_MASK_QP_TYPE = 1,
+	RDMA_COUNTER_MASK_PID = 1 << 1,
 };
 #endif /* _UAPI_RDMA_NETLINK_H */