Messages in this thread Patch in this message | | | From | Zhen Lei <> | Subject | [PATCH 1/1] PCI: Optimize pci_resource_len() to reduce the binary size of kernel | Date | Tue, 13 Jul 2021 15:22:36 +0800 |
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pci_resource_end() can be 0 only when pci_resource_start() is 0. Otherwise, it is definitely an error. In this case, pci_resource_len() should be regarded as 0. Therefore, determining whether pci_resource_start() and pci_resource_end() are both 0 can be reduced to determining only whether pci_resource_end() is 0.
Although only one condition judgment is reduced, the macro function pci_resource_len() is widely referenced in the kernel. I used defconfig to compile the latest kernel on X86, and its binary code size was reduced by about 3KB.
Before: [ 2] .rela.text RELA 0000000000000000 093bfcb0 0000000001a67168 0000000000000018 I 68 1 8
After: [ 2] .rela.text RELA 0000000000000000 093bfcb0 0000000001a66598 0000000000000018 I 68 1 8
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- include/linux/pci.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/include/linux/pci.h b/include/linux/pci.h index 540b377ca8f6..23ef1a15eb5d 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1881,9 +1881,7 @@ int pci_iobar_pfn(struct pci_dev *pdev, int bar, struct vm_area_struct *vma); #define pci_resource_end(dev, bar) ((dev)->resource[(bar)].end) #define pci_resource_flags(dev, bar) ((dev)->resource[(bar)].flags) #define pci_resource_len(dev,bar) \ - ((pci_resource_start((dev), (bar)) == 0 && \ - pci_resource_end((dev), (bar)) == \ - pci_resource_start((dev), (bar))) ? 0 : \ + ((pci_resource_end((dev), (bar)) == 0) ? 0 : \ \ (pci_resource_end((dev), (bar)) - \ pci_resource_start((dev), (bar)) + 1)) -- 2.25.1
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