Messages in this thread | | | Date | Fri, 26 Aug 2011 16:40:53 -0400 | From | Nick Bowler <> | Subject | Re: [PATCH 1/2] mm: convert k{un}map_atomic(p, KM_type) to k{un}map_atomic(p) |
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On 2011-08-26 12:42 -0700, Andrew Morton wrote: > On Fri, 26 Aug 2011 10:58:16 +0200 > Peter Zijlstra <peterz@infradead.org> wrote: > > On Fri, 2011-08-26 at 16:17 +0800, Lin Ming wrote: > > > > > > The KM_type parameter for kmap_atomic/kunmap_atomic is not used > > > anymore since commit 3e4d3af(mm: stack based kmap_atomic()). [...] > > yet-another-massive patch.. (you're the third or fourth to do so) if > > Andrew wants to take this one I won't mind, however previously he > > didn't want flag day patches.. > > I'm OK with cleaning all these up, but I suggest that we leave the > back-compatibility macros in place for a while, to make sure that > various stragglers get converted. Extra marks will be awarded for > working out how to make unconverted code generate a compile warning ;)
It's possible to (ab)use the C preprocessor to accomplish this sort of thing. For instance, consider the following:
#include <stdio.h>
int foo(int x) { return x; }
/* Deprecated; call foo instead. */ static inline int __attribute__((deprecated)) foo_unconverted(int x, int unused) { return foo(x); }
#define PASTE(a, b) a ## b #define PASTE2(a, b) PASTE(a, b) #define NARG_(_9, _8, _7, _6, _5, _4, _3, _2, _1, n, ...) n #define NARG(...) NARG_(__VA_ARGS__, 9, 8, 7, 6, 5, 4, 3, 2, 1, :)
#define foo1(...) foo(__VA_ARGS__) #define foo2(...) foo_unconverted(__VA_ARGS__) #define foo(...) PASTE2(foo, NARG(__VA_ARGS__)(__VA_ARGS__))
int main(void) { printf("%d\n", foo(42)); printf("%d\n", foo(54, 42)); return 0; }
The preprocessor will select between "foo" and "foo_unconverted" depending on the number of arguments passed; and gcc will emit a warning for the latter case:
% gcc test.c test.c: In function ‘main’: test.c:27: warning: ‘foo_unconverted’ is deprecated (declared at test.c:9)
Cheers, -- Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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