[PATCH] net: mlxsw: avoid unused variable warnings

dev_dbg_ratelimited() is a macro that ignores its arguments when DEBUG is
not set, which can lead to unused variable warnings:

ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_sdq_handle':
ethernet/mellanox/mlxsw/pci.c:646:18: warning: unused variable 'pdev' [-Wunused-variable]
ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_rdq_handle':
ethernet/mellanox/mlxsw/pci.c:671:18: warning: unused variable 'pdev' [-Wunused-variable]

This changes the mlxsw driver to remove the local variables we get
warnings for and instead pass the device directly into the API.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/mellanox/mlxsw/pci.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/pci.c b/drivers/net/ethernet/mellanox/mlxsw/pci.c
index 7f4173c8eda3..fdcce03b028d 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/pci.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/pci.c

@@ -643,7 +643,6 @@ static void mlxsw_pci_cqe_sdq_handle(struct mlxsw_pci *mlxsw_pci,
 				     u16 consumer_counter_limit,
 				     char *cqe)
 {
-	struct pci_dev *pdev = mlxsw_pci->pdev;
 	struct mlxsw_pci_queue_elem_info *elem_info;
 	char *wqe;
 	struct sk_buff *skb;

@@ -659,7 +658,7 @@ static void mlxsw_pci_cqe_sdq_handle(struct mlxsw_pci *mlxsw_pci,
 	elem_info->u.sdq.skb = NULL;
 
 	if (q->consumer_counter++ != consumer_counter_limit)
-		dev_dbg_ratelimited(&pdev->dev, "Consumer counter does not match limit in SDQ\n");
+		dev_dbg_ratelimited(&mlxsw_pci->pdev->dev, "Consumer counter does not match limit in SDQ\n");
 	spin_unlock(&q->lock);
 }
 

@@ -668,7 +667,6 @@ static void mlxsw_pci_cqe_rdq_handle(struct mlxsw_pci *mlxsw_pci,
 				     u16 consumer_counter_limit,
 				     char *cqe)
 {
-	struct pci_dev *pdev = mlxsw_pci->pdev;
 	struct mlxsw_pci_queue_elem_info *elem_info;
 	char *wqe;
 	struct sk_buff *skb;

@@ -684,7 +682,7 @@ static void mlxsw_pci_cqe_rdq_handle(struct mlxsw_pci *mlxsw_pci,
 	mlxsw_pci_wqe_frag_unmap(mlxsw_pci, wqe, 0, DMA_FROM_DEVICE);
 
 	if (q->consumer_counter++ != consumer_counter_limit)
-		dev_dbg_ratelimited(&pdev->dev, "Consumer counter does not match limit in RDQ\n");
+		dev_dbg_ratelimited(&mlxsw_pci->pdev->dev, "Consumer counter does not match limit in RDQ\n");
 
 	if (mlxsw_pci_cqe_lag_get(cqe)) {
 		rx_info.is_lag = true;

@@ -706,7 +704,7 @@ static void mlxsw_pci_cqe_rdq_handle(struct mlxsw_pci *mlxsw_pci,
 	memset(wqe, 0, q->elem_size);
 	err = mlxsw_pci_rdq_skb_alloc(mlxsw_pci, elem_info);
 	if (err)
-		dev_dbg_ratelimited(&pdev->dev, "Failed to alloc skb for RDQ\n");
+		dev_dbg_ratelimited(&mlxsw_pci->pdev->dev, "Failed to alloc skb for RDQ\n");
 	/* Everything is set up, ring doorbell to pass elem to HW */
 	q->producer_counter++;
 	mlxsw_pci_queue_doorbell_producer_ring(mlxsw_pci, q);

-- 
2.7.0

On Wed, Mar 23, 2016 at 05:37:38PM +0100, Arnd Bergmann wrote:

dev_dbg_ratelimited() is a macro that ignores its arguments when DEBUG is
not set, which can lead to unused variable warnings:

ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_sdq_handle':
ethernet/mellanox/mlxsw/pci.c:646:18: warning: unused variable 'pdev' [-Wunused-variable]
ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_rdq_handle':
ethernet/mellanox/mlxsw/pci.c:671:18: warning: unused variable 'pdev' [-Wunused-variable]

This changes the mlxsw driver to remove the local variables we get
warnings for and instead pass the device directly into the API.

Hi Arnd

Would it not be better to fix the macro?

I think the issue is that dev_dbg_ratelimited calls no_printk(),
without making use of dev. So how about:

#define dev_dbg_ratelimited(dev, fmt, ...)                              \
({                                                                      \
        if (0)                                                          \
                dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);        \
})

This follows the pattern for other macros for when DEBUG is not defined.

      Andrew

From: Andrew Lunn <andrew@lunn.ch>
Date: Wed, 23 Mar 2016 17:51:11 +0100

On Wed, Mar 23, 2016 at 05:37:38PM +0100, Arnd Bergmann wrote:

quoted

dev_dbg_ratelimited() is a macro that ignores its arguments when DEBUG is
not set, which can lead to unused variable warnings:

ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_sdq_handle':
ethernet/mellanox/mlxsw/pci.c:646:18: warning: unused variable 'pdev' [-Wunused-variable]
ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_rdq_handle':
ethernet/mellanox/mlxsw/pci.c:671:18: warning: unused variable 'pdev' [-Wunused-variable]

This changes the mlxsw driver to remove the local variables we get
warnings for and instead pass the device directly into the API.

Hi Arnd

Would it not be better to fix the macro?

I think the issue is that dev_dbg_ratelimited calls no_printk(),
without making use of dev. So how about:

#define dev_dbg_ratelimited(dev, fmt, ...)                              \
({                                                                      \
        if (0)                                                          \
                dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);        \
})

This follows the pattern for other macros for when DEBUG is not defined.

Yeah, this is probably a better way to fix this problem.

On Wednesday 23 March 2016 14:38:05 David Miller wrote:

From: Andrew Lunn <andrew@lunn.ch>
Date: Wed, 23 Mar 2016 17:51:11 +0100

quoted

On Wed, Mar 23, 2016 at 05:37:38PM +0100, Arnd Bergmann wrote:

quoted

dev_dbg_ratelimited() is a macro that ignores its arguments when DEBUG is
not set, which can lead to unused variable warnings:

ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_sdq_handle':
ethernet/mellanox/mlxsw/pci.c:646:18: warning: unused variable 'pdev' [-Wunused-variable]
ethernet/mellanox/mlxsw/pci.c: In function 'mlxsw_pci_cqe_rdq_handle':
ethernet/mellanox/mlxsw/pci.c:671:18: warning: unused variable 'pdev' [-Wunused-variable]

This changes the mlxsw driver to remove the local variables we get
warnings for and instead pass the device directly into the API.

Hi Arnd

Would it not be better to fix the macro?

I think the issue is that dev_dbg_ratelimited calls no_printk(),
without making use of dev. So how about:

#define dev_dbg_ratelimited(dev, fmt, ...)                              \
({                                                                      \
        if (0)                                                          \
                dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);        \
})

This follows the pattern for other macros for when DEBUG is not defined.

Yeah, this is probably a better way to fix this problem.

Makes sense. I was thrown off by how a related patch recently
modified the no_printk() definition in Fixes: fe22cd9b7c98 ("printk:
help pr_debug and pr_devel to optimize out arguments") around the
same time I ran into the problem in the mlxsw driver.

I'll test build the patch below for a while and submit that if it doesn't
cause any other problems.

diff --git a/include/linux/device.h b/include/linux/device.h
index 002c59728dbe..07f74c246cac 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h

@@ -1293,8 +1293,11 @@ do {									\
 		dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);	\
 } while (0)
 #else
-#define dev_dbg_ratelimited(dev, fmt, ...)			\
-	no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
+#define dev_dbg_ratelimited(dev, fmt, ...)				\
+do {									\
+	if (0)								\
+		dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);	\
+} while (0)
 #endif
 
 #ifdef VERBOSE_DEBUG

Thanks,

	Arnd