ide-floppy: allocate only toplevel packet commands

This makes the top-level function just allocate a single pc entry, and then
pass it down as a pointer to all the helper functions that also need one
of those "struct ide_atapi_pc" things. As far as I can tell, the use of
these things never overlaps each other, BUT I DID NOT CHECK VERY CLOSELY!

So I'm not guaranteeing this is correct, and I don't have the hardware. It
would be good for somebody who knows the code more, and has the hardware,
could please test this?

With this, ide-floppy still has fairly big stack usage, but instead of

	idefloppy_ioctl [vmlinux]:              1208
	ide_floppy_get_capacity [vmlinux]:      872
	idefloppy_release [vmlinux]:            408
	idefloppy_open [vmlinux]:               408

where those two first ones are at the very top of the list of stack users
for me, it's now

	ide_floppy_get_capacity [vmlinux]:           404
	ide_floppy_ioctl [vmlinux]:                  364

ie they are still high, but they are no longer at the top.

Borislav: Since ide_floppy_get_capacity is passed as a function pointer to other
parts of the kernel (e.g., block layer) we need that ide_atapi_pc to be created
on stack. Also, redid stack users numbers above. The two functions missing from
Linus' original 'make stackusage' output are due to ide being
rewritten/reorganized atm.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 30 insertions, 28 deletions

diff --git a/drivers/ide/ide-floppy_ioctl.c b/drivers/ide/ide-floppy_ioctl.c
index 2bc51ff73fee..8f8be8546038 100644
--- a/drivers/ide/ide-floppy_ioctl.c
+++ b/drivers/ide/ide-floppy_ioctl.c
@@ -31,10 +31,11 @@
  * On exit we set nformats to the number of records we've actually initialized.
  */
 
-static int ide_floppy_get_format_capacities(ide_drive_t *drive, int __user *arg)
+static int ide_floppy_get_format_capacities(ide_drive_t *drive,
+                                            struct ide_atapi_pc *pc,
+                                            int __user *arg)
 {
         struct ide_disk_obj *floppy = drive->driver_data;
-        struct ide_atapi_pc pc;
         u8 header_len, desc_cnt;
         int i, blocks, length, u_array_size, u_index;
         int __user *argp;
@@ -45,13 +46,13 @@ static int ide_floppy_get_format_capacities(ide_drive_t *drive, int __user *arg)
         if (u_array_size <= 0)
                 return -EINVAL;
 
-        ide_floppy_create_read_capacity_cmd(&pc);
-        if (ide_queue_pc_tail(drive, floppy->disk, &pc)) {
+        ide_floppy_create_read_capacity_cmd(pc);
+        if (ide_queue_pc_tail(drive, floppy->disk, pc)) {
                 printk(KERN_ERR "ide-floppy: Can't get floppy parameters\n");
                 return -EIO;
         }
 
-        header_len = pc.buf[3];
+        header_len = pc->buf[3];
         desc_cnt = header_len / 8; /* capacity descriptor of 8 bytes */
 
         u_index = 0;
@@ -68,8 +69,8 @@ static int ide_floppy_get_format_capacities(ide_drive_t *drive, int __user *arg)
                 if (u_index >= u_array_size)
                         break;  /* User-supplied buffer too small */
 
-                blocks = be32_to_cpup((__be32 *)&pc.buf[desc_start]);
-                length = be16_to_cpup((__be16 *)&pc.buf[desc_start + 6]);
+                blocks = be32_to_cpup((__be32 *)&pc->buf[desc_start]);
+                length = be16_to_cpup((__be16 *)&pc->buf[desc_start + 6]);
 
                 if (put_user(blocks, argp))
                         return -EFAULT;
@@ -111,29 +112,28 @@ static void ide_floppy_create_format_unit_cmd(struct ide_atapi_pc *pc, int b,
         pc->flags |= PC_FLAG_WRITING;
 }
 
-static int ide_floppy_get_sfrp_bit(ide_drive_t *drive)
+static int ide_floppy_get_sfrp_bit(ide_drive_t *drive, struct ide_atapi_pc *pc)
 {
         struct ide_disk_obj *floppy = drive->driver_data;
-        struct ide_atapi_pc pc;
 
         drive->atapi_flags &= ~IDE_AFLAG_SRFP;
 
-        ide_floppy_create_mode_sense_cmd(&pc, IDEFLOPPY_CAPABILITIES_PAGE);
-        pc.flags |= PC_FLAG_SUPPRESS_ERROR;
+        ide_floppy_create_mode_sense_cmd(pc, IDEFLOPPY_CAPABILITIES_PAGE);
+        pc->flags |= PC_FLAG_SUPPRESS_ERROR;
 
-        if (ide_queue_pc_tail(drive, floppy->disk, &pc))
+        if (ide_queue_pc_tail(drive, floppy->disk, pc))
                 return 1;
 
-        if (pc.buf[8 + 2] & 0x40)
+        if (pc->buf[8 + 2] & 0x40)
                 drive->atapi_flags |= IDE_AFLAG_SRFP;
 
         return 0;
 }
 
-static int ide_floppy_format_unit(ide_drive_t *drive, int __user *arg)
+static int ide_floppy_format_unit(ide_drive_t *drive, struct ide_atapi_pc *pc,
+                                  int __user *arg)
 {
         struct ide_disk_obj *floppy = drive->driver_data;
-        struct ide_atapi_pc pc;
         int blocks, length, flags, err = 0;
 
         if (floppy->openers > 1) {
@@ -166,10 +166,10 @@ static int ide_floppy_format_unit(ide_drive_t *drive, int __user *arg)
                 goto out;
         }
 
-        (void)ide_floppy_get_sfrp_bit(drive);
-        ide_floppy_create_format_unit_cmd(&pc, blocks, length, flags);
+        ide_floppy_get_sfrp_bit(drive, pc);
+        ide_floppy_create_format_unit_cmd(pc, blocks, length, flags);
 
-        if (ide_queue_pc_tail(drive, floppy->disk, &pc))
+        if (ide_queue_pc_tail(drive, floppy->disk, pc))
                 err = -EIO;
 
 out:
@@ -188,15 +188,16 @@ out:
  * the dsc bit, and return either 0 or 65536.
  */
 
-static int ide_floppy_get_format_progress(ide_drive_t *drive, int __user *arg)
+static int ide_floppy_get_format_progress(ide_drive_t *drive,
+                                          struct ide_atapi_pc *pc,
+                                          int __user *arg)
 {
         struct ide_disk_obj *floppy = drive->driver_data;
-        struct ide_atapi_pc pc;
         int progress_indication = 0x10000;
 
         if (drive->atapi_flags & IDE_AFLAG_SRFP) {
-                ide_create_request_sense_cmd(drive, &pc);
-                if (ide_queue_pc_tail(drive, floppy->disk, &pc))
+                ide_create_request_sense_cmd(drive, pc);
+                if (ide_queue_pc_tail(drive, floppy->disk, pc))
                         return -EIO;
 
                 if (floppy->sense_key == 2 &&
@@ -241,20 +242,21 @@ static int ide_floppy_lockdoor(ide_drive_t *drive, struct ide_atapi_pc *pc,
         return 0;
 }
 
-static int ide_floppy_format_ioctl(ide_drive_t *drive, fmode_t mode,
-                                   unsigned int cmd, void __user *argp)
+static int ide_floppy_format_ioctl(ide_drive_t *drive, struct ide_atapi_pc *pc,
+                                   fmode_t mode, unsigned int cmd,
+                                   void __user *argp)
 {
         switch (cmd) {
         case IDEFLOPPY_IOCTL_FORMAT_SUPPORTED:
                 return 0;
         case IDEFLOPPY_IOCTL_FORMAT_GET_CAPACITY:
-                return ide_floppy_get_format_capacities(drive, argp);
+                return ide_floppy_get_format_capacities(drive, pc, argp);
         case IDEFLOPPY_IOCTL_FORMAT_START:
                 if (!(mode & FMODE_WRITE))
                         return -EPERM;
-                return ide_floppy_format_unit(drive, (int __user *)argp);
+                return ide_floppy_format_unit(drive, pc, (int __user *)argp);
         case IDEFLOPPY_IOCTL_FORMAT_GET_PROGRESS:
-                return ide_floppy_get_format_progress(drive, argp);
+                return ide_floppy_get_format_progress(drive, pc, argp);
         default:
                 return -ENOTTY;
         }
@@ -270,7 +272,7 @@ int ide_floppy_ioctl(ide_drive_t *drive, struct block_device *bdev,
         if (cmd == CDROMEJECT || cmd == CDROM_LOCKDOOR)
                 return ide_floppy_lockdoor(drive, &pc, arg, cmd);
 
-        err = ide_floppy_format_ioctl(drive, mode, cmd, argp);
+        err = ide_floppy_format_ioctl(drive, &pc, mode, cmd, argp);
         if (err != -ENOTTY)
                 return err;