diff mbox

[1/3] mmc: initialize struct mmc_command at declaration time

Message ID 1302753463-31005-1-git-send-email-cjb@laptop.org (mailing list archive)
State New, archived
Headers show

Commit Message

Chris Ball April 14, 2011, 3:57 a.m. UTC 
Converts from:
	struct mmc_command cmd;
	memset(&cmd, 0, sizeof(struct mmc_command));

to:
	struct mmc_command cmd = {0};

because it's shorter, as performant, and easier to work out whether
initialization has happened.

Signed-off-by: Chris Ball <cjb@laptop.org>
---
 drivers/mmc/card/block.c    |   13 +++-------
 drivers/mmc/card/mmc_test.c |   22 +++++++------------
 drivers/mmc/core/core.c     |    6 +---
 drivers/mmc/core/mmc_ops.c  |   50 +++++++++++-------------------------------
 drivers/mmc/core/sd_ops.c   |   29 +++++++------------------
 drivers/mmc/core/sdio_ops.c |   11 ++-------
 6 files changed, 38 insertions(+), 93 deletions(-)

Comments

Nicolas Pitre April 14, 2011, 11:37 p.m. UTC | #1 
On Wed, 13 Apr 2011, Chris Ball wrote:

> Converts from:
> 	struct mmc_command cmd;
> 	memset(&cmd, 0, sizeof(struct mmc_command));
> 
> to:
> 	struct mmc_command cmd = {0};
> 
> because it's shorter, as performant, and easier to work out whether
> initialization has happened.

Did you disassemble the resulting binary to make sure this is actually 
as performant?

I'm asking because gcc used to do a horrible dumb job with such patterns 
where it would allocate two instances of the structure on the stack i.e. 
one for the named variable and one for the initializer, then fill the 
later with zeroes, and then call memcpy() to copy the initializer over 
to the named instance.


Nicolas
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Chris Ball April 15, 2011, 3:11 a.m. UTC | #2 
Hi,

On Thu, Apr 14 2011, Nicolas Pitre wrote:
> Did you disassemble the resulting binary to make sure this is actually 
> as performant?
>
> I'm asking because gcc used to do a horrible dumb job with such patterns 
> where it would allocate two instances of the structure on the stack i.e. 
> one for the named variable and one for the initializer, then fill the 
> later with zeroes, and then call memcpy() to copy the initializer over 
> to the named instance.

Nothing horrible as far as I can tell; in fact, the code size on ARM
(stripped mmc_core.ko) decreases by 216 bytes after the patchset here.

Here's a sample disassembly of one function on ARM with gcc-4.6.0, and
diff -y.  Explicit memset (which calls __memzero) on the left, and {0}
initializer (which calls memset) on the right:

00000698 <mmc_set_relative_addr>:			      |	000006c8 <mmc_set_relative_addr>:
 698:	e92d4010 	push	{r4, lr}		      |	 6c8:	e92d4010 	push	{r4, lr}
 69c:	e2504000 	subs	r4, r0, #0		      |	 6cc:	e24dd030 	sub	sp, sp, #48	; 0x30
 6a0:	e24dd030 	sub	sp, sp, #48	; 0x30	      |	 6d0:	e1a04000 	mov	r4, r0
 6a4:	059f0058 	ldreq	r0, [pc, #88]	; 704 <mmc_se |	 6d4:	e3a01000 	mov	r1, #0
 6a8:	03a010ce 	moveq	r1, #206	; 0xce	      |	 6d8:	e1a0000d 	mov	r0, sp
 6ac:	0a000004 	beq	6c4 <mmc_set_relative_addr+0x |	 6dc:	e3a02030 	mov	r2, #48	; 0x30
 6b0:	e5943000 	ldr	r3, [r4]		      |	 6e0:	ebfffffe 	bl	0 <memset>
 6b4:	e3530000 	cmp	r3, #0			      |	 6e4:	e3540000 	cmp	r4, #0
 6b8:	1a000002 	bne	6c8 <mmc_set_relative_addr+0x |	 6e8:	059f0048 	ldreq	r0, [pc, #72]	; 738 <mmc_se
 6bc:	e59f0040 	ldr	r0, [pc, #64]	; 704 <mmc_se |	 6ec:	03a010c4 	moveq	r1, #196	; 0xc4
 6c0:	e3a010cf 	mov	r1, #207	; 0xcf	      |	 6f0:	0a000004 	beq	708 <mmc_set_relative_addr+0x
 6c4:	ebfffffe 	bl	0 <__bug>		      |	 6f4:	e5940000 	ldr	r0, [r4]
 6c8:	e1a0000d 	mov	r0, sp			      |	 6f8:	e3500000 	cmp	r0, #0
 6cc:	e3a01030 	mov	r1, #48	; 0x30		      |	 6fc:	1a000002 	bne	70c <mmc_set_relative_addr+0x
 6d0:	ebfffffe 	bl	0 <__memzero>		      |	 700:	e59f0030 	ldr	r0, [pc, #48]	; 738 <mmc_se
 6d4:	e59430c8 	ldr	r3, [r4, #200]	; 0xc8	      |	 704:	e3a010c5 	mov	r1, #197	; 0xc5
 6d8:	e3a02003 	mov	r2, #3			      |	 708:	ebfffffe 	bl	0 <__bug>
 6dc:	e1a03803 	lsl	r3, r3, #16		      |	 70c:	e59430c8 	ldr	r3, [r4, #200]	; 0xc8
 6e0:	e58d3004 	str	r3, [sp, #4]		      |	 710:	e3a02003 	mov	r2, #3
 6e4:	e5940000 	ldr	r0, [r4]		      |	 714:	e1a03803 	lsl	r3, r3, #16
 6e8:	e3a03015 	mov	r3, #21			      |	 718:	e58d3004 	str	r3, [sp, #4]
 6ec:	e1a0100d 	mov	r1, sp			      |	 71c:	e1a0100d 	mov	r1, sp
 6f0:	e58d2000 	str	r2, [sp]		      |	 720:	e3a03015 	mov	r3, #21
 6f4:	e58d3018 	str	r3, [sp, #24]		      |	 724:	e58d2000 	str	r2, [sp]
 6f8:	ebfffffe 	bl	0 <mmc_wait_for_cmd>	      |	 728:	e58d3018 	str	r3, [sp, #24]
 6fc:	e28dd030 	add	sp, sp, #48	; 0x30	      |	 72c:	ebfffffe 	bl	0 <mmc_wait_for_cmd>
 700:	e8bd8010 	pop	{r4, pc}		      |	 730:	e28dd030 	add	sp, sp, #48	; 0x30
 704:	0000001d 	.word	0x0000001d		      |	 734:	e8bd8010 	pop	{r4, pc}
							      >	 738:	0000001d 	.word	0x0000001d

Thanks,

- Chris.
Chris Ball April 15, 2011, 6:06 p.m. UTC | #3 
Hi,

On Thu, Apr 14 2011, Chris Ball wrote:
> Here's a sample disassembly of one function on ARM with gcc-4.6.0, and
> diff -y.  Explicit memset (which calls __memzero) on the left, and {0}
> initializer (which calls memset) on the right:

(I checked on x86_64 too, and the code's identical -- it's inlined into
a "rep stos %eax,%es:(%rdi)" either way.)

- Chris.
Nicolas Pitre April 15, 2011, 10:37 p.m. UTC | #4 
On Fri, 15 Apr 2011, Chris Ball wrote:

> Hi,
> 
> On Thu, Apr 14 2011, Chris Ball wrote:
> > Here's a sample disassembly of one function on ARM with gcc-4.6.0, and
> > diff -y.  Explicit memset (which calls __memzero) on the left, and {0}
> > initializer (which calls memset) on the right:
> 
> (I checked on x86_64 too, and the code's identical -- it's inlined into
> a "rep stos %eax,%es:(%rdi)" either way.)

Glad to know that gcc is not as dumb as it used to be.


Nicolas
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diff mbox

Patch

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 9e30cf6..93a7efc 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -260,14 +260,12 @@  static u32 mmc_sd_num_wr_blocks(struct mmc_card *card)
 	__be32 *blocks;
 
 	struct mmc_request mrq;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_data data;
 	unsigned int timeout_us;
 
 	struct scatterlist sg;
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_APP_CMD;
 	cmd.arg = card->rca << 16;
 	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
@@ -328,10 +326,9 @@  static u32 mmc_sd_num_wr_blocks(struct mmc_card *card)
 
 static u32 get_card_status(struct mmc_card *card, struct request *req)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int err;
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	cmd.opcode = MMC_SEND_STATUS;
 	if (!mmc_host_is_spi(card->host))
 		cmd.arg = card->rca << 16;
@@ -460,7 +457,7 @@  static inline int mmc_apply_rel_rw(struct mmc_blk_request *brq,
 				   struct request *req)
 {
 	int err;
-	struct mmc_command set_count;
+	struct mmc_command set_count = {0};
 
 	if (!(card->ext_csd.rel_param & EXT_CSD_WR_REL_PARAM_EN)) {
 		/* Legacy mode imposes restrictions on transfers. */
@@ -473,7 +470,6 @@  static inline int mmc_apply_rel_rw(struct mmc_blk_request *brq,
 			brq->data.blocks = 1;
 	}
 
-	memset(&set_count, 0, sizeof(struct mmc_command));
 	set_count.opcode = MMC_SET_BLOCK_COUNT;
 	set_count.arg = brq->data.blocks | (1 << 31);
 	set_count.flags = MMC_RSP_R1 | MMC_CMD_AC;
@@ -501,10 +497,9 @@  static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 		REL_WRITES_SUPPORTED(card);
 
 	do {
-		struct mmc_command cmd;
+		struct mmc_command cmd = {0};
 		u32 readcmd, writecmd, status = 0;
 
-		memset(&cmd, 0, sizeof(struct mmc_command));
 		memset(&brq, 0, sizeof(struct mmc_blk_request));
 		brq.mrq.cmd = &brq.cmd;
 		brq.mrq.data = &brq.data;
diff --git a/drivers/mmc/card/mmc_test.c b/drivers/mmc/card/mmc_test.c
index f5cedec..cc09be8 100644
--- a/drivers/mmc/card/mmc_test.c
+++ b/drivers/mmc/card/mmc_test.c
@@ -201,7 +201,7 @@  static void mmc_test_prepare_mrq(struct mmc_test_card *test,
 }
 
 static int mmc_test_busy(struct mmc_command *cmd)
-{
+
 	return !(cmd->resp[0] & R1_READY_FOR_DATA) ||
 		(R1_CURRENT_STATE(cmd->resp[0]) == 7);
 }
@@ -212,7 +212,7 @@  static int mmc_test_busy(struct mmc_command *cmd)
 static int mmc_test_wait_busy(struct mmc_test_card *test)
 {
 	int ret, busy;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	busy = 0;
 	do {
@@ -247,16 +247,14 @@  static int mmc_test_buffer_transfer(struct mmc_test_card *test,
 	int ret;
 
 	struct mmc_request mrq;
-	struct mmc_command cmd;
-	struct mmc_command stop;
+	struct mmc_command cmd = {0};
+	struct mmc_command stop = {0};
 	struct mmc_data data;
 
 	struct scatterlist sg;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
-	memset(&stop, 0, sizeof(struct mmc_command));
 
 	mrq.cmd = &cmd;
 	mrq.data = &data;
@@ -732,14 +730,12 @@  static int mmc_test_simple_transfer(struct mmc_test_card *test,
 	unsigned blocks, unsigned blksz, int write)
 {
 	struct mmc_request mrq;
-	struct mmc_command cmd;
-	struct mmc_command stop;
+	struct mmc_command cmd = {0};
+	struct mmc_command stop = {0};
 	struct mmc_data data;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
-	memset(&stop, 0, sizeof(struct mmc_command));
 
 	mrq.cmd = &cmd;
 	mrq.data = &data;
@@ -762,16 +758,14 @@  static int mmc_test_broken_transfer(struct mmc_test_card *test,
 	unsigned blocks, unsigned blksz, int write)
 {
 	struct mmc_request mrq;
-	struct mmc_command cmd;
-	struct mmc_command stop;
+	struct mmc_command cmd = {0};
+	struct mmc_command stop = {0};
 	struct mmc_data data;
 
 	struct scatterlist sg;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
-	memset(&stop, 0, sizeof(struct mmc_command));
 
 	mrq.cmd = &cmd;
 	mrq.data = &data;
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 5178d5d..f273ffd 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1286,7 +1286,7 @@  static unsigned int mmc_erase_timeout(struct mmc_card *card,
 static int mmc_do_erase(struct mmc_card *card, unsigned int from,
 			unsigned int to, unsigned int arg)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	unsigned int qty = 0;
 	int err;
 
@@ -1320,7 +1320,6 @@  static int mmc_do_erase(struct mmc_card *card, unsigned int from,
 		to <<= 9;
 	}
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	if (mmc_card_sd(card))
 		cmd.opcode = SD_ERASE_WR_BLK_START;
 	else
@@ -1490,12 +1489,11 @@  EXPORT_SYMBOL(mmc_erase_group_aligned);
 
 int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	if (mmc_card_blockaddr(card) || mmc_card_ddr_mode(card))
 		return 0;
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	cmd.opcode = MMC_SET_BLOCKLEN;
 	cmd.arg = blocklen;
 	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 5f18919..3631ed6 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -23,12 +23,10 @@ 
 static int _mmc_select_card(struct mmc_host *host, struct mmc_card *card)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SELECT_CARD;
 
 	if (card) {
@@ -60,15 +58,13 @@  int mmc_deselect_cards(struct mmc_host *host)
 
 int mmc_card_sleepawake(struct mmc_host *host, int sleep)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_card *card = host->card;
 	int err;
 
 	if (sleep)
 		mmc_deselect_cards(host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SLEEP_AWAKE;
 	cmd.arg = card->rca << 16;
 	if (sleep)
@@ -97,7 +93,7 @@  int mmc_card_sleepawake(struct mmc_host *host, int sleep)
 int mmc_go_idle(struct mmc_host *host)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	/*
 	 * Non-SPI hosts need to prevent chipselect going active during
@@ -113,8 +109,6 @@  int mmc_go_idle(struct mmc_host *host)
 		mmc_delay(1);
 	}
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_GO_IDLE_STATE;
 	cmd.arg = 0;
 	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_NONE | MMC_CMD_BC;
@@ -135,13 +129,11 @@  int mmc_go_idle(struct mmc_host *host)
 
 int mmc_send_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int i, err = 0;
 
 	BUG_ON(!host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SEND_OP_COND;
 	cmd.arg = mmc_host_is_spi(host) ? 0 : ocr;
 	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R3 | MMC_CMD_BCR;
@@ -178,13 +170,11 @@  int mmc_send_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
 int mmc_all_send_cid(struct mmc_host *host, u32 *cid)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!host);
 	BUG_ON(!cid);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_ALL_SEND_CID;
 	cmd.arg = 0;
 	cmd.flags = MMC_RSP_R2 | MMC_CMD_BCR;
@@ -201,13 +191,11 @@  int mmc_all_send_cid(struct mmc_host *host, u32 *cid)
 int mmc_set_relative_addr(struct mmc_card *card)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!card);
 	BUG_ON(!card->host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SET_RELATIVE_ADDR;
 	cmd.arg = card->rca << 16;
 	cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
@@ -223,13 +211,11 @@  static int
 mmc_send_cxd_native(struct mmc_host *host, u32 arg, u32 *cxd, int opcode)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!host);
 	BUG_ON(!cxd);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = opcode;
 	cmd.arg = arg;
 	cmd.flags = MMC_RSP_R2 | MMC_CMD_AC;
@@ -248,7 +234,7 @@  mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
 		u32 opcode, void *buf, unsigned len)
 {
 	struct mmc_request mrq;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_data data;
 	struct scatterlist sg;
 	void *data_buf;
@@ -261,7 +247,6 @@  mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
 		return -ENOMEM;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
 
 	mrq.cmd = &cmd;
@@ -355,11 +340,9 @@  int mmc_send_ext_csd(struct mmc_card *card, u8 *ext_csd)
 
 int mmc_spi_read_ocr(struct mmc_host *host, int highcap, u32 *ocrp)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int err;
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SPI_READ_OCR;
 	cmd.arg = highcap ? (1 << 30) : 0;
 	cmd.flags = MMC_RSP_SPI_R3;
@@ -372,11 +355,9 @@  int mmc_spi_read_ocr(struct mmc_host *host, int highcap, u32 *ocrp)
 
 int mmc_spi_set_crc(struct mmc_host *host, int use_crc)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int err;
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SPI_CRC_ON_OFF;
 	cmd.flags = MMC_RSP_SPI_R1;
 	cmd.arg = use_crc;
@@ -402,14 +383,12 @@  int mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 	       unsigned int timeout_ms)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	u32 status;
 
 	BUG_ON(!card);
 	BUG_ON(!card->host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SWITCH;
 	cmd.arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
 		  (index << 16) |
@@ -451,13 +430,11 @@  EXPORT_SYMBOL_GPL(mmc_switch);
 int mmc_send_status(struct mmc_card *card, u32 *status)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!card);
 	BUG_ON(!card->host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_SEND_STATUS;
 	if (!mmc_host_is_spi(card->host))
 		cmd.arg = card->rca << 16;
@@ -481,7 +458,7 @@  mmc_send_bus_test(struct mmc_card *card, struct mmc_host *host, u8 opcode,
 		  u8 len)
 {
 	struct mmc_request mrq;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_data data;
 	struct scatterlist sg;
 	u8 *data_buf;
@@ -512,7 +489,6 @@  mmc_send_bus_test(struct mmc_card *card, struct mmc_host *host, u8 opcode,
 		memcpy(data_buf, test_buf, len);
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
 
 	mrq.cmd = &cmd;
diff --git a/drivers/mmc/core/sd_ops.c b/drivers/mmc/core/sd_ops.c
index da50849..dfe9a9c 100644
--- a/drivers/mmc/core/sd_ops.c
+++ b/drivers/mmc/core/sd_ops.c
@@ -24,13 +24,11 @@ 
 static int mmc_app_cmd(struct mmc_host *host, struct mmc_card *card)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!host);
 	BUG_ON(card && (card->host != host));
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = MMC_APP_CMD;
 
 	if (card) {
@@ -121,13 +119,11 @@  EXPORT_SYMBOL(mmc_wait_for_app_cmd);
 int mmc_app_set_bus_width(struct mmc_card *card, int width)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!card);
 	BUG_ON(!card->host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = SD_APP_SET_BUS_WIDTH;
 	cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
 
@@ -151,13 +147,11 @@  int mmc_app_set_bus_width(struct mmc_card *card, int width)
 
 int mmc_send_app_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int i, err = 0;
 
 	BUG_ON(!host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = SD_APP_OP_COND;
 	if (mmc_host_is_spi(host))
 		cmd.arg = ocr & (1 << 30); /* SPI only defines one bit */
@@ -196,13 +190,11 @@  int mmc_send_app_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
 
 int mmc_send_if_cond(struct mmc_host *host, u32 ocr)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int err;
 	static const u8 test_pattern = 0xAA;
 	u8 result_pattern;
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	/*
 	 * To support SD 2.0 cards, we must always invoke SD_SEND_IF_COND
 	 * before SD_APP_OP_COND. This command will harmlessly fail for
@@ -230,13 +222,11 @@  int mmc_send_if_cond(struct mmc_host *host, u32 ocr)
 int mmc_send_relative_addr(struct mmc_host *host, unsigned int *rca)
 {
 	int err;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 
 	BUG_ON(!host);
 	BUG_ON(!rca);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = SD_SEND_RELATIVE_ADDR;
 	cmd.arg = 0;
 	cmd.flags = MMC_RSP_R6 | MMC_CMD_BCR;
@@ -254,7 +244,7 @@  int mmc_app_send_scr(struct mmc_card *card, u32 *scr)
 {
 	int err;
 	struct mmc_request mrq;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_data data;
 	struct scatterlist sg;
 	void *data_buf;
@@ -277,7 +267,6 @@  int mmc_app_send_scr(struct mmc_card *card, u32 *scr)
 		return -ENOMEM;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
 
 	mrq.cmd = &cmd;
@@ -317,7 +306,7 @@  int mmc_sd_switch(struct mmc_card *card, int mode, int group,
 	u8 value, u8 *resp)
 {
 	struct mmc_request mrq;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_data data;
 	struct scatterlist sg;
 
@@ -330,7 +319,6 @@  int mmc_sd_switch(struct mmc_card *card, int mode, int group,
 	value &= 0xF;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
 
 	mrq.cmd = &cmd;
@@ -366,7 +354,7 @@  int mmc_app_sd_status(struct mmc_card *card, void *ssr)
 {
 	int err;
 	struct mmc_request mrq;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_data data;
 	struct scatterlist sg;
 
@@ -381,7 +369,6 @@  int mmc_app_sd_status(struct mmc_card *card, void *ssr)
 		return err;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
 
 	mrq.cmd = &cmd;
diff --git a/drivers/mmc/core/sdio_ops.c b/drivers/mmc/core/sdio_ops.c
index dea36d9..f77b1bc 100644
--- a/drivers/mmc/core/sdio_ops.c
+++ b/drivers/mmc/core/sdio_ops.c
@@ -21,13 +21,11 @@ 
 
 int mmc_send_io_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int i, err = 0;
 
 	BUG_ON(!host);
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = SD_IO_SEND_OP_COND;
 	cmd.arg = ocr;
 	cmd.flags = MMC_RSP_SPI_R4 | MMC_RSP_R4 | MMC_CMD_BCR;
@@ -70,7 +68,7 @@  int mmc_send_io_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
 static int mmc_io_rw_direct_host(struct mmc_host *host, int write, unsigned fn,
 	unsigned addr, u8 in, u8 *out)
 {
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	int err;
 
 	BUG_ON(!host);
@@ -80,8 +78,6 @@  static int mmc_io_rw_direct_host(struct mmc_host *host, int write, unsigned fn,
 	if (addr & ~0x1FFFF)
 		return -EINVAL;
 
-	memset(&cmd, 0, sizeof(struct mmc_command));
-
 	cmd.opcode = SD_IO_RW_DIRECT;
 	cmd.arg = write ? 0x80000000 : 0x00000000;
 	cmd.arg |= fn << 28;
@@ -126,7 +122,7 @@  int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn,
 	unsigned addr, int incr_addr, u8 *buf, unsigned blocks, unsigned blksz)
 {
 	struct mmc_request mrq;
-	struct mmc_command cmd;
+	struct mmc_command cmd = {0};
 	struct mmc_data data;
 	struct scatterlist sg;
 
@@ -141,7 +137,6 @@  int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn,
 		return -EINVAL;
 
 	memset(&mrq, 0, sizeof(struct mmc_request));
-	memset(&cmd, 0, sizeof(struct mmc_command));
 	memset(&data, 0, sizeof(struct mmc_data));
 
 	mrq.cmd = &cmd;