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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2016-03-22 22:32:05 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2016-04-11 23:57:09 +0300
commite1f0bce3a0db95007fec756225801e50477f32fd (patch)
tree4bcc48e7ff93364ac1ca0c88404a459b9c9c7774 /drivers/scsi/constants.c
parent9d99a2e33a02c3290cb53013150ee06a304588ae (diff)
downloadlinux-e1f0bce3a0db95007fec756225801e50477f32fd.tar.xz
scsi: reduce CONFIG_SCSI_CONSTANTS=y impact by 8k
On 64 bit, struct error_info has 6 bytes of padding, which amounts to over 4k of wasted space in the additional[] array. We could easily get rid of that by instead using separate arrays for the codes and the pointers. However, we can do even better than that and save an additional 6 bytes per entry: In the table, just store the sizeof() the corresponding string literal. The cumulative sum of these is then the appropriate offset into additional_text, which is built from the concatenation (with '\0's inbetween) of the strings. $ scripts/bloat-o-meter /tmp/vmlinux vmlinux add/remove: 0/0 grow/shrink: 1/1 up/down: 24/-8488 (-8464) function old new delta scsi_extd_sense_format 136 160 +24 additional 11312 2824 -8488 The Kconfig help text used to say that CONFIG_SCSI_CONSTANTS=y costs around 75 KB, but that was a little exaggerated. The actual number was closer to 44K, and 36K with this patch. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Hannes Reinecke <hare@suse.com> Tested-by: Douglas Gilbert <dgilbert@interlog.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/constants.c')
-rw-r--r--drivers/scsi/constants.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/drivers/scsi/constants.c b/drivers/scsi/constants.c
index 6e813eec4f8d..83458f7a2824 100644
--- a/drivers/scsi/constants.c
+++ b/drivers/scsi/constants.c
@@ -292,17 +292,30 @@ bool scsi_opcode_sa_name(int opcode, int service_action,
struct error_info {
unsigned short code12; /* 0x0302 looks better than 0x03,0x02 */
- const char * text;
+ unsigned short size;
};
+/*
+ * There are 700+ entries in this table. To save space, we don't store
+ * (code, pointer) pairs, which would make sizeof(struct
+ * error_info)==16 on 64 bits. Rather, the second element just stores
+ * the size (including \0) of the corresponding string, and we use the
+ * sum of these to get the appropriate offset into additional_text
+ * defined below. This approach saves 12 bytes per entry.
+ */
static const struct error_info additional[] =
{
-#define SENSE_CODE(c, s) {c, s},
+#define SENSE_CODE(c, s) {c, sizeof(s)},
#include "sense_codes.h"
#undef SENSE_CODE
- {0, NULL}
};
+static const char *additional_text =
+#define SENSE_CODE(c, s) s "\0"
+#include "sense_codes.h"
+#undef SENSE_CODE
+ ;
+
struct error_info2 {
unsigned char code1, code2_min, code2_max;
const char * str;
@@ -364,11 +377,14 @@ scsi_extd_sense_format(unsigned char asc, unsigned char ascq, const char **fmt)
{
int i;
unsigned short code = ((asc << 8) | ascq);
+ unsigned offset = 0;
*fmt = NULL;
- for (i = 0; additional[i].text; i++)
+ for (i = 0; i < ARRAY_SIZE(additional); i++) {
if (additional[i].code12 == code)
- return additional[i].text;
+ return additional_text + offset;
+ offset += additional[i].size;
+ }
for (i = 0; additional2[i].fmt; i++) {
if (additional2[i].code1 == asc &&
ascq >= additional2[i].code2_min &&