On 16.05.2023 22:34, Andrew Cooper wrote:
> Following on from the MISRA discussions.
>
> On x86, most are trivial. The two slightly suspect cases are __hvm_copy()
> where constness is dependent on flags,
But do we ever pass string literals into there? I certainly would
like to avoid the explicit casts to get rid of the const there.
> and kextra in __start_xen() which only
> compiles because of laundering the pointer through strstr().
The sole string literal there looks to be the empty string in
cmdline_cook(), which could be easily replaced, I think:
static char * __init cmdline_cook(char *p, const char *loader_name)
{
static char __initdata empty[] = "";
p = p ? : empty;
Yet of course only if we were unhappy with the strstr() side effect.
> The one case which I can't figure out how to fix is EFI:
>
> In file included from arch/x86/efi/boot.c:700:
> arch/x86/efi/efi-boot.h: In function ‘efi_arch_handle_cmdline’:
> arch/x86/efi/efi-boot.h:327:16: error: assignment discards ‘const’
> qualifier from pointer target type [-Werror=discarded-qualifiers]
> 327 | name.s = "xen";
> | ^
> cc1: all warnings being treated as errors
>
> Why do we have something that looks like this ?
>
> union string {
> CHAR16 *w;
> char *s;
> const char *cs;
> };
Because that was the least clutter (at respective use sites) that I
could think of at the time. Looks like you could simply assign to
name.cs, now that we have that field (iirc it wasn't there originally).
Of course that's then only papering over the issue.
> --- a/xen/include/acpi/actypes.h
> +++ b/xen/include/acpi/actypes.h
> @@ -281,7 +281,7 @@ typedef acpi_native_uint acpi_size;
> */
> typedef u32 acpi_status; /* All ACPI Exceptions */
> typedef u32 acpi_name; /* 4-byte ACPI name */
> -typedef char *acpi_string; /* Null terminated ASCII string */
> +typedef const char *acpi_string; /* Null terminated ASCII string */
> typedef void *acpi_handle; /* Actually a ptr to a NS Node */
For all present uses that we have this change looks okay, but changing
this header leaves me a little uneasy. At the same time I have no
better suggestion.
Jan
