[PATCH][next] net: stmmac: replace redundant comparison with true

[PATCH][next] net: stmmac: replace redundant comparison with true

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The comparison of the u32 variable queue with <= zero is always true
since an unsigned can never be negative. Replace the conditional
check with the boolean true to simplify the code.  The while loop
will terminate because of the zero check on queue before queue is
decremented.

Addresses-Coverity: ("Unsigned compared against 0")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index e3e22200a4fd..6e5b4c4b375c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1673,7 +1673,7 @@ static void stmmac_reinit_rx_buffers(struct stmmac_priv *priv)
 	return;
 
 err_reinit_rx_buffers:
-	while (queue >= 0) {
+	while (true) {
 		dma_free_rx_skbufs(priv, queue);
 
 		if (queue == 0)
@@ -1781,7 +1781,7 @@ static int init_dma_rx_desc_rings(struct net_device *dev, gfp_t flags)
 	return 0;
 
 err_init_rx_buffers:
-	while (queue >= 0) {
+	while (true) {
 		struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
 
 		if (rx_q->xsk_pool)
-- 
2.30.2

[PATCH][next] net: stmmac: replace redundant comparison with true

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The comparison of the u32 variable queue with <= zero is always true
since an unsigned can never be negative. Replace the conditional
check with the boolean true to simplify the code.  The while loop
will terminate because of the zero check on queue before queue is
decremented.

Addresses-Coverity: ("Unsigned compared against 0")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index e3e22200a4fd..6e5b4c4b375c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1673,7 +1673,7 @@ static void stmmac_reinit_rx_buffers(struct stmmac_priv *priv)
 	return;
 
 err_reinit_rx_buffers:
-	while (queue >= 0) {
+	while (true) {
 		dma_free_rx_skbufs(priv, queue);
 
 		if (queue == 0)
@@ -1781,7 +1781,7 @@ static int init_dma_rx_desc_rings(struct net_device *dev, gfp_t flags)
 	return 0;
 
 err_init_rx_buffers:
-	while (queue >= 0) {
+	while (true) {
 		struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
 
 		if (rx_q->xsk_pool)
-- 
2.30.2


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Re: [PATCH][next] net: stmmac: replace redundant comparison with true

[Dan Carpenter]

On Thu, Apr 15, 2021 at 09:37:57AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The comparison of the u32 variable queue with <= zero is always true
> since an unsigned can never be negative. Replace the conditional
> check with the boolean true to simplify the code.  The while loop
> will terminate because of the zero check on queue before queue is
> decremented.
> 
> Addresses-Coverity: ("Unsigned compared against 0")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index e3e22200a4fd..6e5b4c4b375c 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1673,7 +1673,7 @@ static void stmmac_reinit_rx_buffers(struct stmmac_priv *priv)
>  	return;
>  
>  err_reinit_rx_buffers:
> -	while (queue >= 0) {

This is an off by one from what the original developer was intending
because we're freeing the most recent queue that wasn't allocated.
In other words, we're freeing everything that we need to plus *one
more thing that we don't need to*.  But it's harmless in this case:

The better fix would be to make queue an int type and do:

	while (--queue >= 0)
		dma_free_rx_skbufs(priv, queue);

Re: [PATCH][next] net: stmmac: replace redundant comparison with true

[Dan Carpenter]

On Thu, Apr 15, 2021 at 09:37:57AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The comparison of the u32 variable queue with <= zero is always true
> since an unsigned can never be negative. Replace the conditional
> check with the boolean true to simplify the code.  The while loop
> will terminate because of the zero check on queue before queue is
> decremented.
> 
> Addresses-Coverity: ("Unsigned compared against 0")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index e3e22200a4fd..6e5b4c4b375c 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1673,7 +1673,7 @@ static void stmmac_reinit_rx_buffers(struct stmmac_priv *priv)
>  	return;
>  
>  err_reinit_rx_buffers:
> -	while (queue >= 0) {

This is an off by one from what the original developer was intending
because we're freeing the most recent queue that wasn't allocated.
In other words, we're freeing everything that we need to plus *one
more thing that we don't need to*.  But it's harmless in this case:

The better fix would be to make queue an int type and do:

	while (--queue >= 0)
		dma_free_rx_skbufs(priv, queue);


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