From db61bfcfe2a68dc71402c270686cd73b80971efc Mon Sep 17 00:00:00 2001 From: "Stephen M. Cameron" Date: Thu, 25 Feb 2010 14:03:22 -0600 Subject: [SCSI] hpsa: Clarify calculation of padding for commandlist structure Signed-off-by: Stephen M. Cameron Signed-off-by: James Bottomley --- drivers/scsi/hpsa_cmd.h | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/scsi/hpsa_cmd.h b/drivers/scsi/hpsa_cmd.h index 3e0abdf76689..43b6f1cffe34 100644 --- a/drivers/scsi/hpsa_cmd.h +++ b/drivers/scsi/hpsa_cmd.h @@ -313,12 +313,18 @@ struct CommandList { void *scsi_cmd; /* on 64 bit architectures, to get this to be 32-byte-aligned - * it so happens we need no padding, on 32 bit systems, - * we need 8 bytes of padding. This does that. + * it so happens we need PAD_64 bytes of padding, on 32 bit systems, + * we need PAD_32 bytes of padding (see below). This does that. + * If it happens that 64 bit and 32 bit systems need different + * padding, PAD_32 and PAD_64 can be set independently, and. + * the code below will do the right thing. */ -#define COMMANDLIST_PAD ((8 - sizeof(long))/4 * 8) +#define IS_32_BIT ((8 - sizeof(long))/4) +#define IS_64_BIT (!IS_32_BIT) +#define PAD_32 (8) +#define PAD_64 (0) +#define COMMANDLIST_PAD (IS_32_BIT * PAD_32 + IS_64_BIT * PAD_64) u8 pad[COMMANDLIST_PAD]; - }; /* Configuration Table Structure */ -- cgit v1.2.3