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SubjectRe: [PATCH v1 2/4] x86/pci: Re-use new dmi_get_bios_year() helper
Hi Andy,

On Thu, 22 Feb 2018 14:59:21 +0200, Andy Shevchenko wrote:
> ...instead of open coding its functionality.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> arch/x86/pci/acpi.c | 8 ++------
> arch/x86/pci/direct.c | 5 ++---
> arch/x86/pci/mmconfig-shared.c | 9 ++-------
> 3 files changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index 7df49c40665e..00e60de30328 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -140,12 +140,8 @@ static const struct dmi_system_id pci_crs_quirks[] __initconst = {
>
> void __init pci_acpi_crs_quirks(void)
> {
> - int year;
> -
> - if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) && year < 2008) {
> - if (iomem_resource.end <= 0xffffffff)
> - pci_use_crs = false;
> - }
> + if ((dmi_get_bios_year() < 2008) && (iomem_resource.end <= 0xffffffff))
> + pci_use_crs = false;

You are changing the behavior here, when DMI does not provide a BIOS
date. Beforehand, the test would fail and pci_use_crs would be left
alone. After your change, dmi_get_bios_year() will return 0, and
"0 < 2008" is true, so pci_use_crs is set to false.

I have no opinion on what this driver should do in such case, but I
certainly wouldn't expect a change of behavior from a "use a helper
instead of open-coding" kind of patch.

I don't think you can safely assume that the code calling
dmi_get_bios_year() will always do the right thing when 0 is being
returned. It's up to the calling code to decide what the default
behavior should be.

Also there are more parentheses than needed.

>
> dmi_check_system(pci_crs_quirks);
>
> diff --git a/arch/x86/pci/direct.c b/arch/x86/pci/direct.c
> index 2d9503323d10..a51074c55982 100644
> --- a/arch/x86/pci/direct.c
> +++ b/arch/x86/pci/direct.c
> @@ -195,14 +195,13 @@ static const struct pci_raw_ops pci_direct_conf2 = {
> static int __init pci_sanity_check(const struct pci_raw_ops *o)
> {
> u32 x = 0;
> - int year, devfn;
> + int devfn;
>
> if (pci_probe & PCI_NO_CHECKS)
> return 1;
> /* Assume Type 1 works for newer systems.
> This handles machines that don't have anything on PCI Bus 0. */
> - dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL);
> - if (year >= 2001)
> + if (dmi_get_bios_year() >= 2001)
> return 1;
>
> for (devfn = 0; devfn < 0x100; devfn++) {
> diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
> index 96684d0adcf9..0b40482578b8 100644
> --- a/arch/x86/pci/mmconfig-shared.c
> +++ b/arch/x86/pci/mmconfig-shared.c
> @@ -547,19 +547,14 @@ static void __init pci_mmcfg_reject_broken(int early)
> static int __init acpi_mcfg_check_entry(struct acpi_table_mcfg *mcfg,
> struct acpi_mcfg_allocation *cfg)
> {
> - int year;
> -
> if (cfg->address < 0xFFFFFFFF)
> return 0;
>
> if (!strncmp(mcfg->header.oem_id, "SGI", 3))
> return 0;
>
> - if (mcfg->header.revision >= 1) {
> - if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) &&
> - year >= 2010)
> - return 0;
> - }
> + if ((mcfg->header.revision >= 1) && (dmi_get_bios_year() >= 2010))
> + return 0;

Here too some parentheses are not needed.

>
> pr_err(PREFIX "MCFG region for %04x [bus %02x-%02x] at %#llx "
> "is above 4GB, ignored\n", cfg->pci_segment,


--
Jean Delvare
SUSE L3 Support

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