linux-kernel - [PATCH v5 5/9] IB/isert: Replace semaphore sem with completion

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Date:   Mon, 21 Nov 2016 11:38:12 +0530
From:   Binoy Jayan <binoy.jayan@...aro.org>
To:     Doug Ledford <dledford@...hat.com>,
        Sean Hefty <sean.hefty@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Hal Rosenstock <hal.rosenstock@...il.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        Sagi Grimberg <sagig@...lanox.com>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        Nicholas Bellinger <nab@...ux-iscsi.org>,
        Jenny Derzhavetz <jennyf@...lanox.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Steve Wise <swise@...ngridcomputing.com>,
        Mark Bloch <markb@...lanox.com>,
        Tatyana E Nikolova <tatyana.e.nikolova@...el.com>,
        Matan Barak <matanb@...lanox.com>,
        Lijun Ou <oulijun@...wei.com>,
        "Wei Hu(Xavier)" <xavier.huwei@...wei.com>
Cc:     Faisal Latif <faisal.latif@...el.com>,
        Mustafa Ismail <mustafa.ismail@...el.com>,
        Mark Brown <broonie@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        target-devel@...r.kernel.org, Binoy Jayan <binoy.jayan@...aro.org>
Subject: [PATCH v5 5/9] IB/isert: Replace semaphore sem with completion

The semaphore 'sem' in isert_device is used as completion, but in a
counting fashion as isert_connected_handler could be called multiple times
during which it allows for that number of waiters (isert_accept_np) to
continue without blocking, each consuming one node out from the list
isert_np-pending in the same order in which they were enqueued (FIFO). So,
convert it to struct completion. Semaphores are going away in the future.

Signed-off-by: Binoy Jayan <binoy.jayan@...aro.org>
---
 drivers/infiniband/ulp/isert/ib_isert.c | 6 +++---
 drivers/infiniband/ulp/isert/ib_isert.h | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 6dd43f6..de80f56 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -619,7 +619,7 @@
 	mutex_unlock(&isert_np->mutex);
 
 	isert_info("np %p: Allow accept_np to continue\n", isert_np);
-	up(&isert_np->sem);
+	complete(&isert_np->comp);
 }
 
 static void
@@ -2311,7 +2311,7 @@ struct rdma_cm_id *
 		isert_err("Unable to allocate struct isert_np\n");
 		return -ENOMEM;
 	}
-	sema_init(&isert_np->sem, 0);
+	init_completion(&isert_np->comp);
 	mutex_init(&isert_np->mutex);
 	INIT_LIST_HEAD(&isert_np->accepted);
 	INIT_LIST_HEAD(&isert_np->pending);
@@ -2427,7 +2427,7 @@ struct rdma_cm_id *
 	int ret;
 
 accept_wait:
-	ret = down_interruptible(&isert_np->sem);
+	ret = wait_for_completion_interruptible(&isert_np->comp);
 	if (ret)
 		return -ENODEV;
 
diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h
index c02ada5..a1277c0 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.h
+++ b/drivers/infiniband/ulp/isert/ib_isert.h
@@ -3,6 +3,7 @@
 #include <linux/in6.h>
 #include <rdma/ib_verbs.h>
 #include <rdma/rdma_cm.h>
+#include <linux/completion.h>
 #include <rdma/rw.h>
 #include <scsi/iser.h>
 
@@ -190,7 +191,7 @@ struct isert_device {
 
 struct isert_np {
 	struct iscsi_np         *np;
-	struct semaphore	sem;
+	struct completion	comp;
 	struct rdma_cm_id	*cm_id;
 	struct mutex		mutex;
 	struct list_head	accepted;
-- 
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