Subject: Re: Re: linux-next: build failure after merge of the rdma tree

From: Jason Gunthorpe <[email-masked]>
Date: Mon, 8 Jul 2019 14:56:34 +0000

On Mon, Jul 08, 2019 at 02:28:13PM +0000, Bernard Metzler wrote:

> Thanks for  bringing this up. Indeed, that explicit
> initialization seem to be inappropriate. Can you please
> fix that as you suggest?

I'm applying this to fix the PER_CPU stuff in siw:

>From 4c7d6dcd364843e408a60952ba914bb72bafc6cc Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <[email-masked]>
Date: Mon, 8 Jul 2019 11:36:32 -0300
Subject: [PATCH] RDMA/siw: Fix DEFINE_PER_CPU compilation when
 ARCH_NEEDS_WEAK_PER_CPU

The initializer for the variable cannot be inside the macro (and zero
initialization isn't needed anyhow).

include/linux/percpu-defs.h:92:33: warning: '__pcpu_unique_use_cnt' initialized and declared 'extern'
  extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name;  \
                                 ^~~~~~~~~~~~~~
include/linux/percpu-defs.h:115:2: note: in expansion of macro 'DEFINE_PER_CPU_SECTION'
  DEFINE_PER_CPU_SECTION(type, name, "")
  ^~~~~~~~~~~~~~~~~~~~~~
drivers/infiniband/sw/siw/siw_main.c:129:8: note: in expansion of macro 'DEFINE_PER_CPU'
 static DEFINE_PER_CPU(atomic_t, use_cnt = ATOMIC_INIT(0));
        ^~~~~~~~~~~~~~

Also the rules for PER_CPU require the variable names to be globally
unique, so prefix them with siw_

Fixes: b9be6f18cf9e ("rdma/siw: transmit path")
Fixes: bdcf26bf9b3a ("rdma/siw: network and RDMA core interface")
Reported-by: Stephen Rothwell <[email-masked]>
Signed-off-by: Jason Gunthorpe <[email-masked]>
---
 drivers/infiniband/sw/siw/siw_main.c  |  8 ++++----
 drivers/infiniband/sw/siw/siw_qp_tx.c | 10 +++++-----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_main.c b/drivers/infiniband/sw/siw/siw_main.c
index 3f5f3d27ebe5a1..fd2552a9091dee 100644
--- a/drivers/infiniband/sw/siw/siw_main.c
+++ b/drivers/infiniband/sw/siw/siw_main.c
@@ -126,7 +126,7 @@ static int siw_dev_qualified(struct net_device *netdev)
 	return 0;
 }
 
-static DEFINE_PER_CPU(atomic_t, use_cnt = ATOMIC_INIT(0));
+static DEFINE_PER_CPU(atomic_t, siw_use_cnt);
 
 static struct {
 	struct cpumask **tx_valid_cpus;
@@ -215,7 +215,7 @@ int siw_get_tx_cpu(struct siw_device *sdev)
 		if (!siw_tx_thread[cpu])
 			continue;
 
-		usage = atomic_read(&per_cpu(use_cnt, cpu));
+		usage = atomic_read(&per_cpu(siw_use_cnt, cpu));
 		if (usage <= min_use) {
 			tx_cpu = cpu;
 			min_use = usage;
@@ -226,7 +226,7 @@ int siw_get_tx_cpu(struct siw_device *sdev)
 
 out:
 	if (tx_cpu >= 0)
-		atomic_inc(&per_cpu(use_cnt, tx_cpu));
+		atomic_inc(&per_cpu(siw_use_cnt, tx_cpu));
 	else
 		pr_warn("siw: no tx cpu found\n");
 
@@ -235,7 +235,7 @@ int siw_get_tx_cpu(struct siw_device *sdev)
 
 void siw_put_tx_cpu(int cpu)
 {
-	atomic_dec(&per_cpu(use_cnt, cpu));
+	atomic_dec(&per_cpu(siw_use_cnt, cpu));
 }
 
 static struct ib_qp *siw_get_base_qp(struct ib_device *base_dev, int id)
diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c
index 5e926fac51db30..1c9fa8fa96e513 100644
--- a/drivers/infiniband/sw/siw/siw_qp_tx.c
+++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
@@ -1183,12 +1183,12 @@ struct tx_task_t {
 	wait_queue_head_t waiting;
 };
 
-static DEFINE_PER_CPU(struct tx_task_t, tx_task_g);
+static DEFINE_PER_CPU(struct tx_task_t, siw_tx_task_g);
 
 void siw_stop_tx_thread(int nr_cpu)
 {
 	kthread_stop(siw_tx_thread[nr_cpu]);
-	wake_up(&per_cpu(tx_task_g, nr_cpu).waiting);
+	wake_up(&per_cpu(siw_tx_task_g, nr_cpu).waiting);
 }
 
 int siw_run_sq(void *data)
@@ -1196,7 +1196,7 @@ int siw_run_sq(void *data)
 	const int nr_cpu = (unsigned int)(long)data;
 	struct llist_node *active;
 	struct siw_qp *qp;
-	struct tx_task_t *tx_task = &per_cpu(tx_task_g, nr_cpu);
+	struct tx_task_t *tx_task = &per_cpu(siw_tx_task_g, nr_cpu);
 
 	init_llist_head(&tx_task->active);
 	init_waitqueue_head(&tx_task->waiting);
@@ -1261,9 +1261,9 @@ int siw_sq_start(struct siw_qp *qp)
 	}
 	siw_qp_get(qp);
 
-	llist_add(&qp->tx_list, &per_cpu(tx_task_g, qp->tx_cpu).active);
+	llist_add(&qp->tx_list, &per_cpu(siw_tx_task_g, qp->tx_cpu).active);
 
-	wake_up(&per_cpu(tx_task_g, qp->tx_cpu).waiting);
+	wake_up(&per_cpu(siw_tx_task_g, qp->tx_cpu).waiting);
 
 	return 0;
 }
-- 
2.21.0