| Message ID | 20210713072236.3043-1-thunder.leizhen@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/1] PCI: Optimize pci_resource_len() to reduce the binary size of kernel | expand |
On Tue, Jul 13, 2021 at 03:22:36PM +0800, Zhen Lei wrote: > 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> Applied to pci/resource for v5.15, thanks! > --- > 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 >
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))
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(-)