linux-kernel - [PATCH v4 15/27] ata: let compiler optimize out ata_eh_set

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Date:   Tue, 17 Mar 2020 15:43:21 +0100
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Michael Schmitz <schmitzmic@...il.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Christoph Hellwig <hch@....de>, linux-ide@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
        b.zolnierkie@...sung.com
Subject: [PATCH v4 15/27] ata: let compiler optimize out ata_eh_set_lpm() on
 non-SATA hosts

Add !IS_ENABLED(CONFIG_SATA_HOST) to ata_eh_set_lpm() to allow
compiler to optimize out the function for non-SATA configs (for
PATA hosts "ap && !ap->ops->set_lpm" condition is always true so
it's sufficient for the function to return zero).

Code size savings on m68k arch using (modified) atari_defconfig:

   text    data     bss     dec     hex filename
before:
  17353      18       0   17371    43db drivers/ata/libata-eh.o
after:
  16607      18       0   16625    40f1 drivers/ata/libata-eh.o

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
---
 drivers/ata/libata-eh.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 3b8d276b5107..452c30024f81 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -3449,7 +3449,8 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 	int rc;
 
 	/* if the link or host doesn't do LPM, noop */
-	if ((link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm))
+	if (!IS_ENABLED(CONFIG_SATA_HOST) ||
+	    (link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm))
 		return 0;
 
 	/*
-- 
2.24.1