> From: Dmitry Kozlyuk [mailto:dmitry.kozl...@gmail.com]
> Sent: Sunday, 21 August 2022 22.50
>
> RTE_PTR_SUB(ptr, x) and RTE_PTR_ALIGN_FLOOR() worked incorrectly
> if "ptr" was an expression:
>
> uint32_t arr[3];
>
> RTE_PTR_SUB(arr + 1, sizeof(arr[0]));
> // expected: (uint32_t *)((uintptr_t)(arr + 1) - 4) == arr
> // actual: (uint32_t *)((uintptr_t) arr + 1 - 4) != arr
>
> RTE_PTR_ALIGN_FLOOR(arr + 2, sizeof(arr[0]));
> // expected: RTE_ALIGN_FLOOR((uintptr_t)(arr + 2), 4) == &arr[2]
> // actual: RTE_ALIGN_FLOOR((uintptr_t) arr + 2, 4) == &arr[0]
>
> Fix the macros and extend the relevant unit test.
Good catch. Serious bugs!
>
> Fixes: af75078fece3 ("first public release")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Dmitry Kozlyuk <dmitry.kozl...@gmail.com>
> ---
> app/test/test_common.c | 11 +++++++++++
> lib/eal/include/rte_common.h | 4 ++--
> 2 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/app/test/test_common.c b/app/test/test_common.c
> index ef177cecb1..4194c1208a 100644
> --- a/app/test/test_common.c
> +++ b/app/test/test_common.c
> @@ -31,6 +31,7 @@ test_macros(int __rte_unused unused_parm)
>
> uintptr_t unused = 0;
> unsigned int smaller = SMALLER, bigger = BIGGER;
> + uint32_t arr[3];
>
> RTE_SET_USED(unused);
>
> @@ -41,6 +42,16 @@ test_macros(int __rte_unused unused_parm)
> FAIL_MACRO(RTE_PTR_ADD);
> if ((uintptr_t)RTE_PTR_SUB(BIGGER, PTR_DIFF) != SMALLER)
> FAIL_MACRO(RTE_PTR_SUB);
> + if (RTE_PTR_ADD(arr + 1, sizeof(arr[0])) != &arr[2])
> + FAIL_MACRO(RTE_PTR_ADD);
> + if (RTE_PTR_SUB(arr + 1, sizeof(arr[0])) != &arr[0])
> + FAIL_MACRO(RTE_PTR_SUB);
Very elegant test cases. :-)
> + if (RTE_PTR_ALIGN_FLOOR(arr + 2, 4) != &arr[2])
> + FAIL_MACRO(RTE_PTR_ALIGN_FLOOR);
> + if (RTE_PTR_ALIGN_CEIL(arr + 2, 4) != &arr[2])
> + FAIL_MACRO(RTE_PTR_ALIGN_CEIL);
While you are at it, consider adding a few more test cases, e.g.
RTE_PTR_ALIGN_FLOOR/CEIL(RTE_PTR_ADD(&arr[1], 1), 4), and
RTE_PTR_ALIGN_FLOOR/CEIL(RTE_PTR_ADD(&arr[1], sizeof(uint32_t) - 1), 4)
> + if (RTE_PTR_ALIGN(arr + 2, 4) != &arr[2])
> + FAIL_MACRO(RTE_PTR_ALIGN);
> if (RTE_PTR_DIFF(BIGGER, SMALLER) != PTR_DIFF)
> FAIL_MACRO(RTE_PTR_DIFF);
> if (RTE_MAX(SMALLER, BIGGER) != BIGGER)
> diff --git a/lib/eal/include/rte_common.h
> b/lib/eal/include/rte_common.h
> index a96cc2a138..d517e9f75f 100644
> --- a/lib/eal/include/rte_common.h
> +++ b/lib/eal/include/rte_common.h
> @@ -295,7 +295,7 @@ static void
> __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
> /**
> * subtract a byte-value offset from a pointer
> */
> -#define RTE_PTR_SUB(ptr, x) ((void*)((uintptr_t)ptr - (x)))
> +#define RTE_PTR_SUB(ptr, x) ((void *)((uintptr_t)(ptr) - (x)))
>
> /**
> * get the difference between two pointer values, i.e. how far apart
> @@ -320,7 +320,7 @@ static void
> __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
> * must be a power-of-two value.
> */
> #define RTE_PTR_ALIGN_FLOOR(ptr, align) \
> - ((typeof(ptr))RTE_ALIGN_FLOOR((uintptr_t)ptr, align))
> + ((typeof(ptr))RTE_ALIGN_FLOOR((uintptr_t)(ptr), align))
>
> /**
> * Macro to align a value to a given power-of-two. The resultant value
> --
> 2.33.1
>
Reviewed-by: Morten Brørup <m...@smartsharesystems.com>
