Re: [PATCH] ACPI/PCI: fix array_size.cocci warnings

[Joe Perches]

On Sat, 2020-07-18 at 16:01 +0800, kernel test robot wrote:
> From: kernel test robot <l...@intel.com>
> 
> drivers/acpi/pci_root.c:150:37-38: WARNING: Use ARRAY_SIZE
> 
>  Use ARRAY_SIZE instead of dividing sizeof array with sizeof an element
[]
>  static char *get_osc_desc(u32 bit)
>  {
> -     int len = sizeof(pci_osc_control_bit) / sizeof(pci_osc_control_bit[0]);
> +     int len = ARRAY_SIZE(pci_osc_control_bit);
>       int i = 0;
>  
>       for (i = 0; i <len; i++)

And likely better to not declare len at all
and ARRAY_SIZE directly instead.

static char *get_osc_desc(u32 bit)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(pci_osc_control_bit); i++) {
                if (bit == pci_osc_control_bit[i].bit)
                        return pci_osc_control_bit[i].desc;
        }

        return NULL;
}

and also likely both arrays should be const.

Something like:
---
 drivers/acpi/pci_root.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index f90e841c59f5..bfb437cf749a 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -122,10 +122,10 @@ static acpi_status try_get_root_bridge_busnr(acpi_handle 
handle,
 
 struct pci_osc_bit_struct {
        u32 bit;
-       char *desc;
+       const char *desc;
 };
 
-static struct pci_osc_bit_struct pci_osc_support_bit[] = {
+static const struct pci_osc_bit_struct pci_osc_support_bit[] = {
        { OSC_PCI_EXT_CONFIG_SUPPORT, "ExtendedConfig" },
        { OSC_PCI_ASPM_SUPPORT, "ASPM" },
        { OSC_PCI_CLOCK_PM_SUPPORT, "ClockPM" },
@@ -135,7 +135,7 @@ static struct pci_osc_bit_struct pci_osc_support_bit[] = {
        { OSC_PCI_HPX_TYPE_3_SUPPORT, "HPX-Type3" },
 };
 
-static struct pci_osc_bit_struct pci_osc_control_bit[] = {
+static const struct pci_osc_bit_struct pci_osc_control_bit[] = {
        { OSC_PCI_EXPRESS_NATIVE_HP_CONTROL, "PCIeHotplug" },
        { OSC_PCI_SHPC_NATIVE_HP_CONTROL, "SHPCHotplug" },
        { OSC_PCI_EXPRESS_PME_CONTROL, "PME" },
@@ -146,17 +146,18 @@ static struct pci_osc_bit_struct pci_osc_control_bit[] = {
 };
 
 static void decode_osc_bits(struct acpi_pci_root *root, char *msg, u32 word,
-                           struct pci_osc_bit_struct *table, int size)
+                           const struct pci_osc_bit_struct *table, int size)
 {
        char buf[80];
        int i, len = 0;
-       struct pci_osc_bit_struct *entry;
 
        buf[0] = '\0';
-       for (i = 0, entry = table; i < size; i++, entry++)
-               if (word & entry->bit)
+       for (i = 0; i < size; i++) {
+               if (word & table->bit)
                        len += scnprintf(buf + len, sizeof(buf) - len, "%s%s",
-                                       len ? " " : "", entry->desc);
+                                       len ? " " : "", table->desc);
+               table++;
+       }
 
        dev_info(&root->device->dev, "_OSC: %s [%s]\n", msg, buf);
 }