On 11/8/18 3:44 PM, Steffen Maier wrote:
Status read buffers (SRBs, unsolicited notifications) never use a QTCB [zfcp_fsf_req_create()]. zfcp_fsf_req_send() already uses this to distinguish SRBs from other FSF request types. We can re-use this method in zfcp_fsf_req_complete(). Introduce a helper function to make the check for req->qtcb less magic. SRBs always are FSF_QTCB_UNSOLICITED_STATUS, so we can hard-code this for the two trace functions dealing with SRBs. All other FSF request types have a QTCB and we can get the fsf_command from there. zfcp_dbf_hba_fsf_response() and thus zfcp_dbf_hba_fsf_res() are only called for non-SRB requests so it's safe to dereference the QTCB [zfcp_fsf_req_complete() returns early on SRB, else calls zfcp_fsf_protstatus_eval() which calls zfcp_dbf_hba_fsf_response()]. In zfcp_scsi_forget_cmnd() we guard the QTCB dereference with a preceding NULL check and rely on boolean shortcut evaluation. As a side effect, this causes an alignment hole which we can close in a later patch after having cleaned up all fields of struct zfcp_fsf_req. Before: $ pahole -C zfcp_fsf_req drivers/s390/scsi/zfcp.ko ... u32 status; /* 136 4 */ u32 fsf_command; /* 140 4 */ struct fsf_qtcb * qtcb; /* 144 8 */ ... After: $ pahole -C zfcp_fsf_req drivers/s390/scsi/zfcp.ko ... u32 status; /* 136 4 */ /* XXX 4 bytes hole, try to pack */ struct fsf_qtcb * qtcb; /* 144 8 */ ... Signed-off-by: Steffen Maier <maier@xxxxxxxxxxxxx> Reviewed-by: Benjamin Block <bblock@xxxxxxxxxxxxx> --- drivers/s390/scsi/zfcp_dbf.c | 8 ++++---- drivers/s390/scsi/zfcp_dbf.h | 4 ++-- drivers/s390/scsi/zfcp_def.h | 7 +++++-- drivers/s390/scsi/zfcp_fsf.c | 14 ++++++-------- drivers/s390/scsi/zfcp_scsi.c | 4 +++- 5 files changed, 20 insertions(+), 17 deletions(-)
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
