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Subject[RFC PATCH-mm] usb: file_storage use unaligned endian helpers rather than private versions
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Use the new helpers for unaligned endian access.  Make some small changes
to reading 24-bit lba values, read the full 32 bit value and mask. Produces
smaller and faster code on x86 and on powerpc.

Coalesce some byte-writes in 32bit writes to allow byteswapping to happen
at compile time and become a 32-bit write without swapping if possible (x86
especially)

This shrinks the size of file_storage.o by ~64 bytes on x86_32.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
---
Alan, what do you think?
drivers/usb/gadget/file_storage.c | 103 +++++++++++++-----------------------
1 files changed, 37 insertions(+), 66 deletions(-)
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index 1aee5b0..91b7466 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -795,37 +795,6 @@ static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep)
return usb_ep_set_halt(ep);
}

-
-/*-------------------------------------------------------------------------*/
-
-/* Routines for unaligned data access */
-
-static u16 get_be16(u8 *buf)
-{
- return ((u16) buf[0] << 8) | ((u16) buf[1]);
-}
-
-static u32 get_be32(u8 *buf)
-{
- return ((u32) buf[0] << 24) | ((u32) buf[1] << 16) |
- ((u32) buf[2] << 8) | ((u32) buf[3]);
-}
-
-static void put_be16(u8 *buf, u16 val)
-{
- buf[0] = val >> 8;
- buf[1] = val;
-}
-
-static void put_be32(u8 *buf, u32 val)
-{
- buf[0] = val >> 24;
- buf[1] = val >> 16;
- buf[2] = val >> 8;
- buf[3] = val & 0xff;
-}
-
-
/*-------------------------------------------------------------------------*/

/*
@@ -1583,9 +1552,9 @@ static int do_read(struct fsg_dev *fsg)
/* Get the starting Logical Block Address and check that it's
* not too big */
if (fsg->cmnd[0] == SC_READ_6)
- lba = (fsg->cmnd[1] << 16) | get_be16(&fsg->cmnd[2]);
+ lba = load_be32_noalign((__be32 *)&fsg->cmnd[0]) & 0xffffff;
else {
- lba = get_be32(&fsg->cmnd[2]);
+ lba = load_be32_noalign((__be32 *)&fsg->cmnd[2]);

/* We allow DPO (Disable Page Out = don't save data in the
* cache) and FUA (Force Unit Access = don't read from the
@@ -1716,9 +1685,9 @@ static int do_write(struct fsg_dev *fsg)
/* Get the starting Logical Block Address and check that it's
* not too big */
if (fsg->cmnd[0] == SC_WRITE_6)
- lba = (fsg->cmnd[1] << 16) | get_be16(&fsg->cmnd[2]);
+ lba = load_be32_noalign((__be32 *)&fsg->cmnd[0]) & 0xffffff;
else {
- lba = get_be32(&fsg->cmnd[2]);
+ lba = load_be32_noalign((__be32 *)&fsg->cmnd[2]);

/* We allow DPO (Disable Page Out = don't save data in the
* cache) and FUA (Force Unit Access = write directly to the
@@ -1952,7 +1921,7 @@ static int do_verify(struct fsg_dev *fsg)

/* Get the starting Logical Block Address and check that it's
* not too big */
- lba = get_be32(&fsg->cmnd[2]);
+ lba = load_be32_noalign((__be32 *)&fsg->cmnd[2]);
if (lba >= curlun->num_sectors) {
curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
return -EINVAL;
@@ -1965,7 +1934,7 @@ static int do_verify(struct fsg_dev *fsg)
return -EINVAL;
}

- verification_length = get_be16(&fsg->cmnd[7]);
+ verification_length = load_be16_noalign((__be16 *)&fsg->cmnd[7]);
if (unlikely(verification_length == 0))
return -EIO; // No default reply

@@ -2115,7 +2084,7 @@ static int do_request_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
memset(buf, 0, 18);
buf[0] = valid | 0x70; // Valid, current error
buf[2] = SK(sd);
- put_be32(&buf[3], sdinfo); // Sense information
+ store_be32_noalign((__be32 *)&buf[3], sdinfo); // Sense information
buf[7] = 18 - 8; // Additional sense length
buf[12] = ASC(sd);
buf[13] = ASCQ(sd);
@@ -2126,9 +2095,9 @@ static int do_request_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
static int do_read_capacity(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
struct lun *curlun = fsg->curlun;
- u32 lba = get_be32(&fsg->cmnd[2]);
+ u32 lba = load_be32_noalign((__be32 *)&fsg->cmnd[2]);
int pmi = fsg->cmnd[8];
- u8 *buf = (u8 *) bh->buf;
+ __be32 *buf = (__be32 *)bh->buf;

/* Check the PMI and LBA fields */
if (pmi > 1 || (pmi == 0 && lba != 0)) {
@@ -2136,8 +2105,8 @@ static int do_read_capacity(struct fsg_dev *fsg, struct fsg_buffhd *bh)
return -EINVAL;
}

- put_be32(&buf[0], curlun->num_sectors - 1); // Max logical block
- put_be32(&buf[4], 512); // Block length
+ store_be32_noalign(&buf[0], curlun->num_sectors - 1); // Max logical block
+ store_be32_noalign(&buf[1], 512); // Block length
return 8;
}

@@ -2156,7 +2125,7 @@ static void store_cdrom_address(u8 *dest, int msf, u32 addr)
dest[0] = 0; /* Reserved */
} else {
/* Absolute sector */
- put_be32(dest, addr);
+ store_be32_noalign((__be32 *)dest, addr);
}
}

@@ -2164,7 +2133,7 @@ static int do_read_header(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
struct lun *curlun = fsg->curlun;
int msf = fsg->cmnd[1] & 0x02;
- u32 lba = get_be32(&fsg->cmnd[2]);
+ u32 lba = load_be32_noalign((__be32 *)&fsg->cmnd[2]);
u8 *buf = (u8 *) bh->buf;

if ((fsg->cmnd[1] & ~0x02) != 0) { /* Mask away MSF */
@@ -2264,10 +2233,13 @@ static int do_mode_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
buf[2] = 0x04; // Write cache enable,
// Read cache not disabled
// No cache retention priorities
- put_be16(&buf[4], 0xffff); // Don't disable prefetch
+ // Don't disable prefetch
+ store_be16_noalign((__be16 *)&buf[4], 0xffff);
// Minimum prefetch = 0
- put_be16(&buf[8], 0xffff); // Maximum prefetch
- put_be16(&buf[10], 0xffff); // Maximum prefetch ceiling
+ // Maximum prefetch
+ store_be16_noalign((__be16 *)&buf[8], 0xffff);
+ // Maximum prefetch ceiling
+ store_be16_noalign((__be16 *)&buf[10], 0xffff);
}
buf += 12;
}
@@ -2284,7 +2256,7 @@ static int do_mode_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
if (mscmnd == SC_MODE_SENSE_6)
buf0[0] = len - 1;
else
- put_be16(buf0, len - 2);
+ store_be16_noalign((__be16 *)buf0, len - 2);
return len;
}

@@ -2366,15 +2338,14 @@ static int do_read_format_capacities(struct fsg_dev *fsg,
struct fsg_buffhd *bh)
{
struct lun *curlun = fsg->curlun;
- u8 *buf = (u8 *) bh->buf;
-
- buf[0] = buf[1] = buf[2] = 0;
- buf[3] = 8; // Only the Current/Maximum Capacity Descriptor
- buf += 4;
-
- put_be32(&buf[0], curlun->num_sectors); // Number of blocks
- put_be32(&buf[4], 512); // Block length
- buf[4] = 0x02; // Current capacity
+ __be32 *buf = (__be32 *)bh->buf;
+
+ // Only the Current/Maximum Capacity Descriptor
+ store_be32_noalign(&buf[0], 8);
+ // Number of blocks
+ store_be32_noalign(&buf[1], curlun->num_sectors);
+ // Current capacity, Block length
+ store_be32_noalign(&buf[2], (0x02 << 24) | 512);
return 12;
}

@@ -2894,7 +2865,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
break;

case SC_MODE_SELECT_10:
- fsg->data_size_from_cmnd = get_be16(&fsg->cmnd[7]);
+ fsg->data_size_from_cmnd = load_be16_noalign((__be16 *)&fsg->cmnd[7]);
if ((reply = check_command(fsg, 10, DATA_DIR_FROM_HOST,
(1<<1) | (3<<7), 0,
"MODE SELECT(10)")) == 0)
@@ -2910,7 +2881,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
break;

case SC_MODE_SENSE_10:
- fsg->data_size_from_cmnd = get_be16(&fsg->cmnd[7]);
+ fsg->data_size_from_cmnd = load_be16_noalign((__be16 *)&fsg->cmnd[7]);
if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
(1<<1) | (1<<2) | (3<<7), 0,
"MODE SENSE(10)")) == 0)
@@ -2935,7 +2906,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
break;

case SC_READ_10:
- fsg->data_size_from_cmnd = get_be16(&fsg->cmnd[7]) << 9;
+ fsg->data_size_from_cmnd = load_be16_noalign((__be16 *)&fsg->cmnd[7]) << 9;
if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
(1<<1) | (0xf<<2) | (3<<7), 1,
"READ(10)")) == 0)
@@ -2943,7 +2914,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
break;

case SC_READ_12:
- fsg->data_size_from_cmnd = get_be32(&fsg->cmnd[6]) << 9;
+ fsg->data_size_from_cmnd = load_be32_noalign((__be32 *)&fsg->cmnd[6]) << 9;
if ((reply = check_command(fsg, 12, DATA_DIR_TO_HOST,
(1<<1) | (0xf<<2) | (0xf<<6), 1,
"READ(12)")) == 0)
@@ -2961,7 +2932,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
case SC_READ_HEADER:
if (!mod_data.cdrom)
goto unknown_cmnd;
- fsg->data_size_from_cmnd = get_be16(&fsg->cmnd[7]);
+ fsg->data_size_from_cmnd = load_be16_noalign((__be16 *)&fsg->cmnd[7]);
if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
(3<<7) | (0x1f<<1), 1,
"READ HEADER")) == 0)
@@ -2971,7 +2942,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
case SC_READ_TOC:
if (!mod_data.cdrom)
goto unknown_cmnd;
- fsg->data_size_from_cmnd = get_be16(&fsg->cmnd[7]);
+ fsg->data_size_from_cmnd = load_be16_noalign((__be16 *)&fsg->cmnd[7]);
if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
(7<<6) | (1<<1), 1,
"READ TOC")) == 0)
@@ -2979,7 +2950,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
break;

case SC_READ_FORMAT_CAPACITIES:
- fsg->data_size_from_cmnd = get_be16(&fsg->cmnd[7]);
+ fsg->data_size_from_cmnd = load_be16_noalign((__be16 *)&fsg->cmnd[7]);
if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
(3<<7), 1,
"READ FORMAT CAPACITIES")) == 0)
@@ -3037,7 +3008,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
break;

case SC_WRITE_10:
- fsg->data_size_from_cmnd = get_be16(&fsg->cmnd[7]) << 9;
+ fsg->data_size_from_cmnd = load_be16_noalign((__be16 *)&fsg->cmnd[7]) << 9;
if ((reply = check_command(fsg, 10, DATA_DIR_FROM_HOST,
(1<<1) | (0xf<<2) | (3<<7), 1,
"WRITE(10)")) == 0)
@@ -3045,7 +3016,7 @@ static int do_scsi_command(struct fsg_dev *fsg)
break;

case SC_WRITE_12:
- fsg->data_size_from_cmnd = get_be32(&fsg->cmnd[6]) << 9;
+ fsg->data_size_from_cmnd = load_be32_noalign((__be32 *)&fsg->cmnd[6]) << 9;
if ((reply = check_command(fsg, 12, DATA_DIR_FROM_HOST,
(1<<1) | (0xf<<2) | (0xf<<6), 1,
"WRITE(12)")) == 0)
--
1.6.1.rc1.262.gb6810




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