cdrom: reduce stack usage of mmc_ioctl_dvd_read_struct

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>

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index b927aa2..cceace6 100644 (file)
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -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];
@@ -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];
@@ -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) {
@@ -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",
@@ -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;
@@ -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;
 
@@ -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: