WARNING: 'successfull' may be misspelled - perhaps 'successful'?
#9: 
clean after a successfull .prepare_data() as per the documentation.
              ^^^^^^^^^^^

total: 0 errors, 1 warnings, 0 checks, 38 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

Commit cdb1d56aefce ("net: ethtool: Don't call .cleanup_data when prepare_data fails") has style problems, please review.

NOTE: Ignored message types: ALLOC_SIZEOF_STRUCT BAD_REPORTED_BY_LINK CAMELCASE COMMIT_LOG_LONG_LINE GIT_COMMIT_ID MACRO_ARG_REUSE NO_AUTHOR_SIGN_OFF

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.
total: 0 errors, 1 warnings, 0 checks, 38 lines checked