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cdrom: reduce stack usage of mmc_ioctl_dvd_read_struct
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1. kmalloc 192 bytes in dvd_read_bca (which is inlined into dvd_read_struct)
2. Pass struct packet_command to all dvd_read_* functions.

Checkstack output:
Before: mmc_ioctl_dvd_read_struct:         280
After:  mmc_ioctl_dvd_read_struct:         56

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Marcin Slusarz authored and Jens Axboe committed Dec 29, 2008
1 parent 3147c53 commit d194139
Showing 1 changed file with 77 additions and 62 deletions.
139 changes: 77 additions & 62 deletions drivers/cdrom/cdrom.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1712,29 +1712,30 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
return 0;
}

static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s)
static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s,
struct packet_command *cgc)
{
unsigned char buf[21], *base;
struct dvd_layer *layer;
struct packet_command cgc;
struct cdrom_device_ops *cdo = cdi->ops;
int ret, layer_num = s->physical.layer_num;

if (layer_num >= DVD_LAYERS)
return -EINVAL;

init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc.cmd[6] = layer_num;
cgc.cmd[7] = s->type;
cgc.cmd[9] = cgc.buflen & 0xff;
init_cdrom_command(cgc, buf, sizeof(buf), CGC_DATA_READ);
cgc->cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc->cmd[6] = layer_num;
cgc->cmd[7] = s->type;
cgc->cmd[9] = cgc->buflen & 0xff;

/*
* refrain from reporting errors on non-existing layers (mainly)
*/
cgc.quiet = 1;
cgc->quiet = 1;

if ((ret = cdo->generic_packet(cdi, &cgc)))
ret = cdo->generic_packet(cdi, cgc);
if (ret)
return ret;

base = &buf[4];
Expand Down Expand Up @@ -1762,21 +1763,22 @@ static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s)
return 0;
}

static int dvd_read_copyright(struct cdrom_device_info *cdi, dvd_struct *s)
static int dvd_read_copyright(struct cdrom_device_info *cdi, dvd_struct *s,
struct packet_command *cgc)
{
int ret;
u_char buf[8];
struct packet_command cgc;
struct cdrom_device_ops *cdo = cdi->ops;

init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc.cmd[6] = s->copyright.layer_num;
cgc.cmd[7] = s->type;
cgc.cmd[8] = cgc.buflen >> 8;
cgc.cmd[9] = cgc.buflen & 0xff;
init_cdrom_command(cgc, buf, sizeof(buf), CGC_DATA_READ);
cgc->cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc->cmd[6] = s->copyright.layer_num;
cgc->cmd[7] = s->type;
cgc->cmd[8] = cgc->buflen >> 8;
cgc->cmd[9] = cgc->buflen & 0xff;

if ((ret = cdo->generic_packet(cdi, &cgc)))
ret = cdo->generic_packet(cdi, cgc);
if (ret)
return ret;

s->copyright.cpst = buf[4];
Expand All @@ -1785,79 +1787,89 @@ static int dvd_read_copyright(struct cdrom_device_info *cdi, dvd_struct *s)
return 0;
}

static int dvd_read_disckey(struct cdrom_device_info *cdi, dvd_struct *s)
static int dvd_read_disckey(struct cdrom_device_info *cdi, dvd_struct *s,
struct packet_command *cgc)
{
int ret, size;
u_char *buf;
struct packet_command cgc;
struct cdrom_device_ops *cdo = cdi->ops;

size = sizeof(s->disckey.value) + 4;

if ((buf = kmalloc(size, GFP_KERNEL)) == NULL)
buf = kmalloc(size, GFP_KERNEL);
if (!buf)
return -ENOMEM;

init_cdrom_command(&cgc, buf, size, CGC_DATA_READ);
cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc.cmd[7] = s->type;
cgc.cmd[8] = size >> 8;
cgc.cmd[9] = size & 0xff;
cgc.cmd[10] = s->disckey.agid << 6;
init_cdrom_command(cgc, buf, size, CGC_DATA_READ);
cgc->cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc->cmd[7] = s->type;
cgc->cmd[8] = size >> 8;
cgc->cmd[9] = size & 0xff;
cgc->cmd[10] = s->disckey.agid << 6;

if (!(ret = cdo->generic_packet(cdi, &cgc)))
ret = cdo->generic_packet(cdi, cgc);
if (!ret)
memcpy(s->disckey.value, &buf[4], sizeof(s->disckey.value));

kfree(buf);
return ret;
}

static int dvd_read_bca(struct cdrom_device_info *cdi, dvd_struct *s)
static int dvd_read_bca(struct cdrom_device_info *cdi, dvd_struct *s,
struct packet_command *cgc)
{
int ret;
u_char buf[4 + 188];
struct packet_command cgc;
int ret, size = 4 + 188;
u_char *buf;
struct cdrom_device_ops *cdo = cdi->ops;

init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc.cmd[7] = s->type;
cgc.cmd[9] = cgc.buflen & 0xff;
buf = kmalloc(size, GFP_KERNEL);
if (!buf)
return -ENOMEM;

if ((ret = cdo->generic_packet(cdi, &cgc)))
return ret;
init_cdrom_command(cgc, buf, size, CGC_DATA_READ);
cgc->cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc->cmd[7] = s->type;
cgc->cmd[9] = cgc->buflen & 0xff;

ret = cdo->generic_packet(cdi, cgc);
if (ret)
goto out;

s->bca.len = buf[0] << 8 | buf[1];
if (s->bca.len < 12 || s->bca.len > 188) {
cdinfo(CD_WARNING, "Received invalid BCA length (%d)\n", s->bca.len);
return -EIO;
ret = -EIO;
goto out;
}
memcpy(s->bca.value, &buf[4], s->bca.len);

return 0;
ret = 0;
out:
kfree(buf);
return ret;
}

static int dvd_read_manufact(struct cdrom_device_info *cdi, dvd_struct *s)
static int dvd_read_manufact(struct cdrom_device_info *cdi, dvd_struct *s,
struct packet_command *cgc)
{
int ret = 0, size;
u_char *buf;
struct packet_command cgc;
struct cdrom_device_ops *cdo = cdi->ops;

size = sizeof(s->manufact.value) + 4;

if ((buf = kmalloc(size, GFP_KERNEL)) == NULL)
buf = kmalloc(size, GFP_KERNEL);
if (!buf)
return -ENOMEM;

init_cdrom_command(&cgc, buf, size, CGC_DATA_READ);
cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc.cmd[7] = s->type;
cgc.cmd[8] = size >> 8;
cgc.cmd[9] = size & 0xff;
init_cdrom_command(cgc, buf, size, CGC_DATA_READ);
cgc->cmd[0] = GPCMD_READ_DVD_STRUCTURE;
cgc->cmd[7] = s->type;
cgc->cmd[8] = size >> 8;
cgc->cmd[9] = size & 0xff;

if ((ret = cdo->generic_packet(cdi, &cgc))) {
kfree(buf);
return ret;
}
ret = cdo->generic_packet(cdi, cgc);
if (ret)
goto out;

s->manufact.len = buf[0] << 8 | buf[1];
if (s->manufact.len < 0 || s->manufact.len > 2048) {
Expand All @@ -1868,27 +1880,29 @@ static int dvd_read_manufact(struct cdrom_device_info *cdi, dvd_struct *s)
memcpy(s->manufact.value, &buf[4], s->manufact.len);
}

out:
kfree(buf);
return ret;
}

static int dvd_read_struct(struct cdrom_device_info *cdi, dvd_struct *s)
static int dvd_read_struct(struct cdrom_device_info *cdi, dvd_struct *s,
struct packet_command *cgc)
{
switch (s->type) {
case DVD_STRUCT_PHYSICAL:
return dvd_read_physical(cdi, s);
return dvd_read_physical(cdi, s, cgc);

case DVD_STRUCT_COPYRIGHT:
return dvd_read_copyright(cdi, s);
return dvd_read_copyright(cdi, s, cgc);

case DVD_STRUCT_DISCKEY:
return dvd_read_disckey(cdi, s);
return dvd_read_disckey(cdi, s, cgc);

case DVD_STRUCT_BCA:
return dvd_read_bca(cdi, s);
return dvd_read_bca(cdi, s, cgc);

case DVD_STRUCT_MANUFACT:
return dvd_read_manufact(cdi, s);
return dvd_read_manufact(cdi, s, cgc);

default:
cdinfo(CD_WARNING, ": Invalid DVD structure read requested (%d)\n",
Expand Down Expand Up @@ -3027,7 +3041,8 @@ static noinline int mmc_ioctl_cdrom_pause_resume(struct cdrom_device_info *cdi,
}

static noinline int mmc_ioctl_dvd_read_struct(struct cdrom_device_info *cdi,
void __user *arg)
void __user *arg,
struct packet_command *cgc)
{
int ret;
dvd_struct *s;
Expand All @@ -3046,7 +3061,7 @@ static noinline int mmc_ioctl_dvd_read_struct(struct cdrom_device_info *cdi,
return -EFAULT;
}

ret = dvd_read_struct(cdi, s);
ret = dvd_read_struct(cdi, s, cgc);
if (ret)
goto out;

Expand Down Expand Up @@ -3132,7 +3147,7 @@ static int mmc_ioctl(struct cdrom_device_info *cdi, unsigned int cmd,
case CDROMRESUME:
return mmc_ioctl_cdrom_pause_resume(cdi, &cgc, cmd);
case DVD_READ_STRUCT:
return mmc_ioctl_dvd_read_struct(cdi, userptr);
return mmc_ioctl_dvd_read_struct(cdi, userptr, &cgc);
case DVD_AUTH:
return mmc_ioctl_dvd_auth(cdi, userptr);
case CDROM_NEXT_WRITABLE:
Expand Down

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