MFC r324644 (by imp):

Closer examination shows that nvme and CAM both normally zero-fill
allocations (for req and ccb, which ultimately contain the
nvme_cmd). As such, we can micro-optimize these routines. Add a
comment to this effect, and bzero the ccb used to make the requests
for the nda dump rotuine so it more closely matches a ccb allocated
with xpt_get_ccb().

2 files changed, 8 insertions, 8 deletions

diff --git a/sys/cam/nvme/nvme_da.c b/sys/cam/nvme/nvme_da.c
index 7791369..652f330 100644
--- a/sys/cam/nvme/nvme_da.c
+++ b/sys/cam/nvme/nvme_da.c
@@ -398,6 +398,8 @@ ndadump(void *arg, void *virtual, vm_offset_t physical, off_t offset, size_t len
 		return (ENXIO);
 	}
 
+	/* xpt_get_ccb returns a zero'd allocation for the ccb, mimic that here */
+	memset(&nvmeio, 0, sizeof(nvmeio));
 	if (length > 0) {
 		xpt_setup_ccb(&ccb.ccb_h, periph->path, CAM_PRIORITY_NORMAL);
 		ccb.ccb_h.ccb_state = NDA_CCB_DUMP;
diff --git a/sys/dev/nvme/nvme.h b/sys/dev/nvme/nvme.h
index 3e6a424..aff4fbc 100644
--- a/sys/dev/nvme/nvme.h
+++ b/sys/dev/nvme/nvme.h
@@ -1068,7 +1068,12 @@ uint32_t	nvme_ns_get_stripesize(struct nvme_namespace *ns);
 int	nvme_ns_bio_process(struct nvme_namespace *ns, struct bio *bp,
 			    nvme_cb_fn_t cb_fn);
 
-/* Command building helper functions -- shared with CAM */
+/*
+ * Command building helper functions -- shared with CAM
+ * These functions assume allocator zeros out cmd structure
+ * CAM's xpt_get_ccb and the request allocator for nvme both
+ * do zero'd allocations.
+ */
 static inline
 void	nvme_ns_flush_cmd(struct nvme_command *cmd, uint32_t nsid)
 {
@@ -1082,17 +1087,10 @@ void	nvme_ns_rw_cmd(struct nvme_command *cmd, uint32_t rwcmd, uint32_t nsid,
     uint64_t lba, uint32_t count)
 {
 	cmd->opc = rwcmd;
-	cmd->fuse = 0;
-	cmd->rsvd1 = 0;
 	cmd->nsid = nsid;
-	cmd->rsvd2 = 0;
-	cmd->rsvd3 = 0;
 	cmd->cdw10 = lba & 0xffffffffu;
 	cmd->cdw11 = lba >> 32;
 	cmd->cdw12 = count-1;
-	cmd->cdw13 = 0;
-	cmd->cdw14 = 0;
-	cmd->cdw15 = 0;
 }
 
 static inline