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SubjectRe: [PATCH -next] pci: fix a -Wtype-limits compilation warning


On 2019-12-18 10:00 a.m., Qian Cai wrote:
> The commit a7d06153eea2 ("PCI: Fix pci_add_dma_alias() bitmask size")
> introduced a compilation warning and a potential infinite loop because
> it is no longer possible to be self-terminated as u8 is always less than
> 256,
>
> In file included from ./include/linux/kernel.h:12,
> from ./include/asm-generic/bug.h:19,
> from ./arch/x86/include/asm/bug.h:83,
> from ./include/linux/bug.h:5,
> from ./include/linux/jump_label.h:250,
> from ./arch/x86/include/asm/string_64.h:6,
> from ./arch/x86/include/asm/string.h:5,
> from ./include/linux/string.h:20,
> from ./include/linux/uuid.h:12,
> from ./include/linux/mod_devicetable.h:13,
> from ./include/linux/pci.h:27,
> from drivers/pci/search.c:11:
> drivers/pci/search.c: In function 'pci_for_each_dma_alias':
> ./include/linux/bitops.h:30:13: warning: comparison is always true due
> to limited range of data type [-Wtype-limits]
> (bit) < (size); \
> ^
> drivers/pci/search.c:46:3: note: in expansion of macro 'for_each_set_bit'
> for_each_set_bit(devfn, pdev->dma_alias_mask, MAX_NR_DEVFNS) {
>
> Fixed it by using u16 for "devfn" in this occasion.
>
> Fixes: a7d06153eea2 ("PCI: Fix pci_add_dma_alias() bitmask size")
> Signed-off-by: Qian Cai <cai@lca.pw>

Makes sense to me,

Reviewed-by: Logan Gunthorpe <logang@deltatee.com>


> ---
> drivers/pci/search.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/search.c b/drivers/pci/search.c
> index 9e4dfae47252..42bc44d0e681 100644
> --- a/drivers/pci/search.c
> +++ b/drivers/pci/search.c
> @@ -41,7 +41,7 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
> * DMA, iterate over that too.
> */
> if (unlikely(pdev->dma_alias_mask)) {
> - u8 devfn;
> + u16 devfn;
>
> for_each_set_bit(devfn, pdev->dma_alias_mask, MAX_NR_DEVFNS) {
> ret = fn(pdev, PCI_DEVID(pdev->bus->number, devfn),
>

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