[PATCH] libata-eh: Use switch() instead of sparse array for protocol strings

Geert Uytterhoeven
2017-01-09T14:50:28Z

Replace the sparse 256-pointer array for looking up protocol strings by
a switch() statement to reduce kernel size.

According to bloat-o-meter, this saves 910 bytes on m68k (32-bit), and
1892 bytes on arm64 (64-bit).

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
drivers/ata/libata-eh.c | 44 +++++++++++++++++++++++++++++++-------------
1 file changed, 31 insertions(+), 13 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 0e1ec37070d19b64..e7196fc29ff09434 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2606,21 +2606,39 @@ static void ata_eh_link_report(struct ata_link *link)
[DMA_TO_DEVICE] = "out",
[DMA_FROM_DEVICE] = "in",
};
- static const char *prot_str[] = {
- [ATA_PROT_UNKNOWN] = "unknown",
- [ATA_PROT_NODATA] = "nodata",
- [ATA_PROT_PIO] = "pio",
- [ATA_PROT_DMA] = "dma",
- [ATA_PROT_NCQ] = "ncq dma",
- [ATA_PROT_NCQ_NODATA] = "ncq nodata",
- [ATAPI_PROT_NODATA] = "nodata",
- [ATAPI_PROT_PIO] = "pio",
- [ATAPI_PROT_DMA] = "dma",
- };
+ const char *prot_str = NULL;

+ switch (qc->tf.protocol) {
+ case ATA_PROT_UNKNOWN:
+ prot_str = "unknown";
+ break;
+ case ATA_PROT_NODATA:
+ prot_str = "nodata";
+ break;
+ case ATA_PROT_PIO:
+ prot_str = "pio";
+ break;
+ case ATA_PROT_DMA:
+ prot_str = "dma";
+ break;
+ case ATA_PROT_NCQ:
+ prot_str = "ncq dma";
+ break;
+ case ATA_PROT_NCQ_NODATA:
+ prot_str = "ncq nodata";
+ break;
+ case ATAPI_PROT_NODATA:
+ prot_str = "nodata";
+ break;
+ case ATAPI_PROT_PIO:
+ prot_str = "pio";
+ break;
+ case ATAPI_PROT_DMA:
+ prot_str = "dma";
+ break;
+ }
snprintf(data_buf, sizeof(data_buf), " %s %u %s",
- prot_str[qc->tf.protocol], qc->nbytes,
- dma_str[qc->dma_dir]);
+ prot_str, qc->nbytes, dma_str[qc->dma_dir]);
}

if (ata_is_atapi(qc->tf.protocol)) {
--
1.9.1