KVM: selftests: Move test_read() into elf.c and delete lib/io.c

lib/io.c has outlived its purpose.  test_read() has exactly one caller,
lib/elf.c; test_write() has none at all; and test_seq_read() is a
declaration in test_util.h with no definition anywhere in the tree.

Both surviving helpers open with

	TEST_ASSERT(count >= 0, "Unexpected count, count: %li", count);

which can never fire, because @count is a size_t.  Building with -Wextra
points this out:

  lib/io.c:51:27: warning: comparison of unsigned expression in '>= 0'
                  is always true [-Wtype-limits]
  lib/io.c:128:27: warning: comparison of unsigned expression in '>= 0'
                  is always true [-Wtype-limits]

The comment above each assertion is worse than the assertion itself: it
cites the read(2) and write(2) manpages to claim that a count of zero is
allowed, but a zero count lands in "case 0" and fails the test outright.
The helper has never accepted what the comment promises.

Move test_read() into elf.c as a static elf_read(), named for what it
does rather than reading as "test the read() syscall", and assert that
@count is non-zero, which is what the code has always required and what
every caller already passes.  Drop the commentary describing retry
behaviour that the code makes obvious.  Nothing is then left in
lib/io.c, so remove the file along with test_write() and the stale
test_seq_read() declaration.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/all/aqxNbR9u5F1sqB3p@google.com
Signed-off-by: Gokul K <gokul02k@gmail.com>
Link: https://patch.msgid.link/20260918054420.338842-1-gokul02k@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions