On Mon, Jul 17, 2023 at 6:11 PM Yury Norov [off-list ref] wrote:

On Mon, Jul 17, 2023 at 01:37:05PM +0200, Alexander Potapenko wrote:

quoted

Add basic tests ensuring that values can be added at arbitrary positions
of the bitmap, including those spanning into the adjacent unsigned
longs.

Signed-off-by: Alexander Potapenko <glider@google.com>

Thanks for the test!

quoted

---
This patch was previously called
"lib/test_bitmap: add tests for bitmap_{set,get}_value_unaligned"

v3:
 - switch to using bitmap_{set,get}_value()
 - change the expected bit pattern in test_set_get_value(),
   as the test was incorrectly assuming 0 is the LSB.
---
 lib/test_bitmap.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 187f5b2db4cf1..c2ab54040c249 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c

@@ -71,6 +71,17 @@ __check_eq_uint(const char *srcfile, unsigned int line,
      return true;
 }

+static bool __init
+__check_eq_ulong(const char *srcfile, unsigned int line,
+              const unsigned long exp_ulong, unsigned long x)
+{
+     if (exp_ulong != x) {
+             pr_err("[%s:%u] expected %lu, got %lu\n",
+                     srcfile, line, exp_ulong, x);
+             return false;
+     }
+     return true;
+}

 static bool __init
 __check_eq_bitmap(const char *srcfile, unsigned int line,

@@ -186,6 +197,7 @@ __check_eq_str(const char *srcfile, unsigned int line,
      })

 #define expect_eq_uint(...)          __expect_eq(uint, ##__VA_ARGS__)
+#define expect_eq_ulong(...)         __expect_eq(ulong, ##__VA_ARGS__)
 #define expect_eq_bitmap(...)                __expect_eq(bitmap, ##__VA_ARGS__)
 #define expect_eq_pbl(...)           __expect_eq(pbl, ##__VA_ARGS__)
 #define expect_eq_u32_array(...)     __expect_eq(u32_array, ##__VA_ARGS__)

@@ -1222,6 +1234,25 @@ static void __init test_bitmap_const_eval(void)
      BUILD_BUG_ON(~var != ~BIT(25));
 }

+static void __init test_set_get_value(void)
+{
+     DECLARE_BITMAP(bitmap, BITS_PER_LONG * 2);

It's too short. Can you make it long enough to ensure it works as
expected when start is not in the 1st word, and start+nbits is in
the following word.

quoted

+     unsigned long val;
+     int i;
+
+     for (i = 0; i < BITS_PER_LONG * 2 - 7; i++) {
+             bitmap_zero(bitmap, BITS_PER_LONG * 2);
+             bitmap_set_value(bitmap, 0b10101UL, i, 5);
+             val = bitmap_get_value(bitmap, i, 5);
+             expect_eq_ulong(0b10101UL, val);

Can you also check that the rest of bitmap is untouched?
Something like:

        DECLARE_BITMAP(bitmap, ...);
        DECLARE_BITMAP(orig, ...);

        memset(orig, 0x5a, ...);
        memset(bitmap, 0x5a, ...);

        for (j = start; j < start + nbits; j++)
                if (val & BIT(j - start))
                        __set_bit(j, orig);
                else
                        __clear_bit(j, orig);

        bitmap_set_value(bitmap, val, start, nbits);
        expect_eq_bitmap(orig, bitmap, ...);

I like this kind of testing because it gives people a better
understanding of what happens behind all that optimization tricks.

Will do. In fact the difference between GENMASK(n, 0) and GENMASK(n-1,
0) discussed in the other patch requires exactly this kind of testing.

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