[PATCH v2] PCI: pciehp: Refactor infinite loop in pcie_poll_cmd()

[PATCH v2] PCI: pciehp: Refactor infinite loop in pcie_poll_cmd()

[Andy Shevchenko]

Infinite timeout loops are hard to read. Refactor it
to plausible 'do {} while ()'.

Note, the supplied timeout can't be negative for current use,
though if it's not dividable to 10, we may go below 0,
that's why type of the parameter is int. And thus, we may move
the check to the loop condition.

No functional changes implied.

Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
- corrected loop conditional to include 0 comparison (Keith)
- added Rb (Andrew)
 drivers/pci/hotplug/pciehp_hpc.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 86d97f3112f0..764384153c7d 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -68,7 +68,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
 	struct pci_dev *pdev = ctrl_dev(ctrl);
 	u16 slot_status;
 
-	while (true) {
+	do {
 		pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
 		if (slot_status == (u16) ~0) {
 			ctrl_info(ctrl, "%s: no response from device\n",
@@ -81,11 +81,9 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
 						   PCI_EXP_SLTSTA_CC);
 			return 1;
 		}
-		if (timeout < 0)
-			break;
 		msleep(10);
 		timeout -= 10;
-	}
+	} while (timeout >= 0);
 	return 0;	/* timeout */
 }
 
-- 
2.24.0.rc1

Re: [PATCH v2] PCI: pciehp: Refactor infinite loop in pcie_poll_cmd()

[Bjorn Helgaas]

On Fri, Nov 08, 2019 at 01:18:55PM +0200, Andy Shevchenko wrote:
> Infinite timeout loops are hard to read. Refactor it
> to plausible 'do {} while ()'.
> 
> Note, the supplied timeout can't be negative for current use,
> though if it's not dividable to 10, we may go below 0,
> that's why type of the parameter is int. And thus, we may move
> the check to the loop condition.
> 
> No functional changes implied.
> 
> Reviewed-by: Andrew Murray <andrew.murray@arm.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Applied to pci/hotplug for v5.5, thanks!

> ---
> - corrected loop conditional to include 0 comparison (Keith)
> - added Rb (Andrew)
>  drivers/pci/hotplug/pciehp_hpc.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 86d97f3112f0..764384153c7d 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -68,7 +68,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>  	struct pci_dev *pdev = ctrl_dev(ctrl);
>  	u16 slot_status;
>  
> -	while (true) {
> +	do {
>  		pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
>  		if (slot_status == (u16) ~0) {
>  			ctrl_info(ctrl, "%s: no response from device\n",
> @@ -81,11 +81,9 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>  						   PCI_EXP_SLTSTA_CC);
>  			return 1;
>  		}
> -		if (timeout < 0)
> -			break;
>  		msleep(10);
>  		timeout -= 10;
> -	}
> +	} while (timeout >= 0);
>  	return 0;	/* timeout */
>  }
>  
> -- 
> 2.24.0.rc1
>