While working of this "[PATCH v4] Make SCSI Status CONDITION MET equivalent to GOOD" the author had trouble finding how to add another corner case check in the scsi_io_completion() function (scsi_lib.c). That function is executed at the completion of every SCSI command but only 20 or so of its hundred of lines of code are executed for the vast majority of invocations (i.e. the fastpath).
This patch refactors scsi_io_completion() by taking the bulk of its error processing code into three static helper functions, leaving only the 20 or so code lines that constitute the fastpath. In this process comments were added and tweaked, plus variables renamed. The last two patches in this set are optional: adding conditional hints along the fastpath and converting 3 BUG() calls in scsi_io_completion() to WARNs as requested by a reviewer. There is no attempt in this patchset to change the logic of the original scsi_io_completion(). Some conditional checks are saved by reducing the number of redundant tests (e.g. on the 'result' variable being non-zero). Also De Morgan's laws are applied to some complex conditions to simplify them from the reader's perspective. The fact remains, this is a very complex function. This patch is against Martin Petersen's 4.17/scsi-queue branch. Douglas Gilbert (7): scsi_io_completion comment on end_request return scsi_io_completion rename variables scsi_io_completion_nz_result function added scsi_io_completion_action helper added scsi_io_completion_reprep helper added scsi_io_completion hints on fastpatch scsi_io_completion convert BUGs to WARNs drivers/scsi/scsi_lib.c | 376 +++++++++++++++++++++++++++--------------------- 1 file changed, 213 insertions(+), 163 deletions(-) -- 2.14.1
