Messages in this thread | | | Date | Thu, 12 Aug 2010 18:24:39 +0200 | From | Jiri Slaby <> | Subject | Re: [PATCH v2] BLOCK: fix bio.bi_rw handling |
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On 08/12/2010 06:08 PM, Christoph Hellwig wrote: > On Thu, Aug 12, 2010 at 02:31:06PM +0200, Jiri Slaby wrote: >> Return of the bi_rw tests is no longer bool after commit 74450be1. But >> results of such tests are stored in bools. This doesn't fit in there >> for some compilers (gcc 4.5 here), so either use !! magic to get real >> bools or use ulong where the result is assigned somewhere. > > I'd have to look at my copy of the C standard if it's guaranteed,
§6.5.3.3 of ANSI C99, par 5: The result of the logical negation operator ! is 0 if the value of its operand compares unequal to 0, 1 if the value of its operand compares equal to 0. The result has type int. The expression !E is equivalent to (0==E).
On == (§6.5.9 par 3): The == (equal to) and != (not equal to) operators are analogous to the relational operators except for their lower precedence. Each of the operators yields 1 if the specified relation is true and 0 if it is false. The result has type int. For any pair of operands, exactly one of the relations is true.
On bool => _Bool (§6.2.5 par 2) An object declared as type _Bool is large enough to store the values 0 and 1.
So it should be safe :).
BTW just of curiosity, sizeof(bool) is 1 here (8 bits).
regards, -- js -- 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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