>>>>> "Matthew" == Matthew Wilcox <matthew@xxxxxx> writes:
Matthew> And are these performance path? If not, it might be nice to
Matthew> move them out of line and code them like this:
I compared the object files for the two approaches and it looks like
indexing into the array is a clear win compared to the switch statement.
Also, the DIF case must return the chosen protection type and not
true/false.
scsi: Fix incorrect reporting of host protection capabilities
The advent of DIF Type 2 devices exposed some missing break statements
in the protection mask switch constructs. However, rewriting the code
to use an index into a small static array seemed like a more elegant
solution.
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 6e728b1..47941fc 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -797,30 +797,23 @@ static inline unsigned int scsi_host_get_prot(struct Scsi_Host *shost)
static inline unsigned int scsi_host_dif_capable(struct Scsi_Host *shost, unsigned int target_type)
{
- switch (target_type) {
- case 1:
- if (shost->prot_capabilities & SHOST_DIF_TYPE1_PROTECTION)
- return target_type;
- case 2:
- if (shost->prot_capabilities & SHOST_DIF_TYPE2_PROTECTION)
- return target_type;
- case 3:
- if (shost->prot_capabilities & SHOST_DIF_TYPE3_PROTECTION)
- return target_type;
- }
+ static unsigned char cap[] = { 0,
+ SHOST_DIF_TYPE1_PROTECTION,
+ SHOST_DIF_TYPE2_PROTECTION,
+ SHOST_DIF_TYPE3_PROTECTION };
- return 0;
+ return shost->prot_capabilities & cap[target_type] ? target_type : 0;
}
static inline unsigned int scsi_host_dix_capable(struct Scsi_Host *shost, unsigned int target_type)
{
#if defined(CONFIG_BLK_DEV_INTEGRITY)
- switch (target_type) {
- case 0: return shost->prot_capabilities & SHOST_DIX_TYPE0_PROTECTION;
- case 1: return shost->prot_capabilities & SHOST_DIX_TYPE1_PROTECTION;
- case 2: return shost->prot_capabilities & SHOST_DIX_TYPE2_PROTECTION;
- case 3: return shost->prot_capabilities & SHOST_DIX_TYPE3_PROTECTION;
- }
+ static unsigned char cap[] = { SHOST_DIX_TYPE0_PROTECTION,
+ SHOST_DIX_TYPE1_PROTECTION,
+ SHOST_DIX_TYPE2_PROTECTION,
+ SHOST_DIX_TYPE3_PROTECTION };
+
+ return shost->prot_capabilities & cap[target_type];
#endif
return 0;
}
--
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