• Masami Hiramatsu's avatar
    error-injection: Add injectable error types · 663faf9f
    Masami Hiramatsu authored
    Add injectable error types for each error-injectable function.
    
    One motivation of error injection test is to find software flaws,
    mistakes or mis-handlings of expectable errors. If we find such
    flaws by the test, that is a program bug, so we need to fix it.
    
    But if the tester miss input the error (e.g. just return success
    code without processing anything), it causes unexpected behavior
    even if the caller is correctly programmed to handle any errors.
    That is not what we want to test by error injection.
    
    To clarify what type of errors the caller must expect for each
    injectable function, this introduces injectable error types:
    
     - EI_ETYPE_NULL : means the function will return NULL if it
    		    fails. No ERR_PTR, just a NULL.
     - EI_ETYPE_ERRNO : means the function will return -ERRNO
    		    if it fails.
     - EI_ETYPE_ERRNO_NULL : means the function will return -ERRNO
    		       (ERR_PTR) or NULL.
    
    ALLOW_ERROR_INJECTION() macro is expanded to get one of
    NULL, ERRNO, ERRNO_NULL to record the error type for
    each function. e.g.
    
     ALLOW_ERROR_INJECTION(open_ctree, ERRNO)
    
    This error types are shown in debugfs as below.
    
      ====
      / # cat /sys/kernel/debug/error_injection/list
      open_ctree [btrfs]	ERRNO
      io_ctl_init [btrfs]	ERRNO
      ====
    Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
    Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
    Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
    663faf9f