linux-kernel - [PATCH v2 1/2] net/mlx4_core: clean up cq_res_start_move

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Message-ID: <1389728736.28068.8.camel@x220>
Date:	Tue, 14 Jan 2014 20:45:36 +0100
From:	Paul Bolle <pebolle@...cali.nl>
To:	Or Gerlitz <ogerlitz@...lanox.com>,
	Jack Morgenstein <jackm@....mellanox.co.il>,
	Rony Efraim <ronye@...lanox.com>,
	Hadar Hen Zion <hadarh@...lanox.com>,
	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/2] net/mlx4_core: clean up cq_res_start_move_to()

Building resource_tracker.o triggers a GCC warning:
    drivers/net/ethernet/mellanox/mlx4/resource_tracker.c: In function 'mlx4_HW2SW_CQ_wrapper':
    drivers/net/ethernet/mellanox/mlx4/resource_tracker.c:3019:16: warning: 'cq' may be used uninitialized in this function [-Wmaybe-uninitialized]
      atomic_dec(&cq->mtt->ref_count);
                    ^

This is a false positive. But a cleanup of cq_res_start_move_to() can
help GCC here. The code currently uses a switch statement where an
if/else construct would do too, since only two of the switch's four
cases can ever occur. Dropping that switch makes the warning go away.

While we're at it, add some missing braces.

Signed-off-by: Paul Bolle <pebolle@...cali.nl>
---
v2: adjust to Jack's review.

 .../net/ethernet/mellanox/mlx4/resource_tracker.c  | 52 ++++++++--------------
 1 file changed, 19 insertions(+), 33 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c b/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c
index 2f3f2bc..15cd659 100644
--- a/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c
+++ b/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c
@@ -1340,43 +1340,29 @@ static int cq_res_start_move_to(struct mlx4_dev *dev, int slave, int cqn,
 
 	spin_lock_irq(mlx4_tlock(dev));
 	r = res_tracker_lookup(&tracker->res_tree[RES_CQ], cqn);
-	if (!r)
+	if (!r) {
 		err = -ENOENT;
-	else if (r->com.owner != slave)
+	} else if (r->com.owner != slave) {
 		err = -EPERM;
-	else {
-		switch (state) {
-		case RES_CQ_BUSY:
-			err = -EBUSY;
-			break;
-
-		case RES_CQ_ALLOCATED:
-			if (r->com.state != RES_CQ_HW)
-				err = -EINVAL;
-			else if (atomic_read(&r->ref_count))
-				err = -EBUSY;
-			else
-				err = 0;
-			break;
-
-		case RES_CQ_HW:
-			if (r->com.state != RES_CQ_ALLOCATED)
-				err = -EINVAL;
-			else
-				err = 0;
-			break;
-
-		default:
+	} else if (state == RES_CQ_ALLOCATED) {
+		if (r->com.state != RES_CQ_HW)
 			err = -EINVAL;
-		}
+		else if (atomic_read(&r->ref_count))
+			err = -EBUSY;
+		else
+			err = 0;
+	} else if (state != RES_CQ_HW || r->com.state != RES_CQ_ALLOCATED) {
+		err = -EINVAL;
+	} else {
+		err = 0;
+	}
 
-		if (!err) {
-			r->com.from_state = r->com.state;
-			r->com.to_state = state;
-			r->com.state = RES_CQ_BUSY;
-			if (cq)
-				*cq = r;
-		}
+	if (!err) {
+		r->com.from_state = r->com.state;
+		r->com.to_state = state;
+		r->com.state = RES_CQ_BUSY;
+		if (cq)
+			*cq = r;
 	}
 
 	spin_unlock_irq(mlx4_tlock(dev));
-- 
1.8.4.2


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