Re: [PATCH] perf/x86/uncore: fix compilation warning in snb_uncore_imc_init_box()

From: Peter Zijlstra
Date: Tue Mar 11 2014 - 07:14:18 EST


On Tue, Mar 11, 2014 at 11:44:33AM +0100, Stephane Eranian wrote:
>
>
> This patches fixes a compilation problem (unused variable) with the
> new SNB/IVB/HSW uncore IMC code.
>
> Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> index b262c61..3846a37 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
> @@ -1722,15 +1722,19 @@ static struct attribute_group snb_uncore_imc_format_group = {
> static void snb_uncore_imc_init_box(struct intel_uncore_box *box)
> {
> struct pci_dev *pdev = box->pci_dev;
> - u32 addr_lo, addr_hi;
> + u32 addr_lo;
> resource_size_t addr;
>
> pci_read_config_dword(pdev, SNB_UNCORE_PCI_IMC_BAR_OFFSET, &addr_lo);
> addr = addr_lo;
>
> #ifdef CONFIG_PHYS_ADDR_T_64BIT
> - pci_read_config_dword(pdev, SNB_UNCORE_PCI_IMC_BAR_OFFSET+4, &addr_hi);
> - addr = ((resource_size_t)addr_hi << 32) | addr_lo;
> + { u32 addr_hi;
> + int where = SNB_UNCORE_PCI_IMC_BAR_OFFSET + 4;
> +
> + pci_read_config_dword(pdev, where, &addr_hi);
> + addr = ((resource_size_t)addr_hi << 32) | addr_lo;
> + }
> #endif

How about something like:

- u32 addr_lo, addr_hi;
+ u32 pci_dword;

pci_read_config_dword(pdev, SNB_UNCORE_PCI_IMC_BAR_OFFSET, &pci_dword);
addr = pci_dword;

#ifdef ..
pci_read_config_dword(pdev, SNB_UNCORE_PCI_IMC_BAR_OFFSET + 4, &pci_dword);
addr |= ((u64)pci_dword) << 32;
#endif

That avoids the need for the ugly {} thing.
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