selftests/bpf: Fix off-by-one in bpf_cpumask_populate related selftest

The test_populate test uses >= instead of > when checking if the
runtime nr_cpus exceeds the bit capacity of a cpumask_t.

On a system where the physical CPU core count perfectly matches the
CONFIG_NR_CPUS upper bound (e.g. nr_cpus = 512 and CONFIG_NR_CPUS =
512), the condition nr_cpus >= CPUMASK_TEST_MASKLEN * 8 evaluates to
true (512 >= 512). This incorrectly causes the test to fail with an
error value of 3.

A 512-bit cpumask_t provides enough bits (indices 0 through 511) to
represent 512 CPUs. The subsequent bpf_for(i, 0, nr_cpus) loop
iterates up to nr_cpus - 1 (511), which perfectly aligns with the
maximum valid index of the bitmask.

Change the condition to nr_cpus > CPUMASK_TEST_MASKLEN * 8 to fix the
false positive failure on these systems.

Fixes: 918ba2636d4e ("selftests: bpf: add bpf_cpumask_populate selftests")
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Acked-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/bpf/20260420093734.2400330-1-mattbobrowski@google.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

0 files changed, 0 insertions, 0 deletions