Messages in this thread Patch in this message | | | Date | Fri, 18 Mar 2005 00:43:33 +0100 (CET) | From | Jesper Juhl <> | Subject | [PATCH] avoid signed vs unsigned comparison in efi_range_is_wc() |
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This little function in include/linux/efi.h :
static inline int efi_range_is_wc(unsigned long start, unsigned long len) { int i;
for (i = 0; i < len; i += (1UL << EFI_PAGE_SHIFT)) { unsigned long paddr = __pa(start + i); if (!(efi_mem_attributes(paddr) & EFI_MEMORY_WC)) return 0; } /* The range checked out */ return 1; }
generates this warning when building with gcc -W :
include/linux/efi.h: In function `efi_range_is_wc': include/linux/efi.h:320: warning: comparison between signed and unsigned
It looks to me like a significantly large 'len' passed in could cause the loop to never end. Isn't it safer to make 'i' an unsigned long as well? Like this little patch below (which of course also kills the warning) :
Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
diff -up linux-2.6.11-mm4-orig/include/linux/efi.h linux-2.6.11-mm4/include/linux/efi.h --- linux-2.6.11-mm4-orig/include/linux/efi.h 2005-03-16 15:45:35.000000000 +0100 +++ linux-2.6.11-mm4/include/linux/efi.h 2005-03-18 00:34:36.000000000 +0100 @@ -315,7 +315,7 @@ extern struct efi_memory_map memmap; */ static inline int efi_range_is_wc(unsigned long start, unsigned long len) { - int i; + unsigned long i; for (i = 0; i < len; i += (1UL << EFI_PAGE_SHIFT)) { unsigned long paddr = __pa(start + i);
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