Re: suspend2 merge (was Re: [Suspend2-devel] Re: CFS and suspend2: hang in atomic copy)

Pavel Machek
2007-04-26T10:41:26Z

Hi!

> > The interface isn't even 64/32-bit compatible...
>
> Which parts?
>
> ioctl(AVAIL_SWAP,
> ...hmm, is this the one you are complaining about? It returns
> loff_t through a pointer. Maybe there's another interface
> that can return available swap, and we should use that,
> instead?

loff_t is 64bit on i386, so I do not see immediate problem here, but
maybe we should just explicitely pass u64?

> ioctl(GET_SWAP_PAGE,
> returns sector_t through a pointer. NOt sure if that's good
> idea, either.

Ok, that's very bad idea, because sector_t can be 32-bit or 64-bit,
depending on CONFIG_LBD. We need to use u64 here.

> ioctl(SET_SWAP_FILE,
> does old_decode_dev(arg). Is that ok?
>
> ioctl(SET_SWAP_AREA,
> shares struct resume_swap_area between user and kernel. I
> guess that's bad..?

struct resume_swap_area {
loff_t offset;
u_int32_t dev;
} __attribute__((packed));

...I guess we should change loff_t -> u64 and problem is solved?

Old_decode_dev takes u16. That sucks for majors/minors > 256, but
fortunately those are not common.

Does this seem to help?
Pavel

diff --git a/kernel/power/power.h b/kernel/power/power.h
index eb461b8..dc13af5 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -114,7 +114,7 @@ extern int snapshot_image_loaded(struct
* SNAPSHOT_SET_SWAP_AREA ioctl
*/
struct resume_swap_area {
- loff_t offset;
+ u_int64_t offset;
u_int32_t dev;
} __attribute__((packed));

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 558e18e..d0730c1 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -215,8 +215,7 @@ static int snapshot_ioctl(struct inode *
{
int error = 0;
struct snapshot_data *data;
- loff_t avail;
- sector_t offset;
+ u64 avail, offset;

if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
return -ENOTTY;
@@ -286,7 +285,7 @@ static int snapshot_ioctl(struct inode *
case SNAPSHOT_AVAIL_SWAP:
avail = count_swap_pages(data->swap, 1);
avail <<= PAGE_SHIFT;
- error = put_user(avail, (loff_t __user *)arg);
+ error = put_user(avail, (u64 __user *)arg);
break;

case SNAPSHOT_GET_SWAP_PAGE:
@@ -304,7 +303,7 @@ static int snapshot_ioctl(struct inode *
offset = alloc_swapdev_block(data->swap, data->bitmap);
if (offset) {
offset <<= PAGE_SHIFT;
- error = put_user(offset, (sector_t __user *)arg);
+ error = put_user(offset, (u64 __user *)arg);
} else {
error = -ENOSPC;
}

--
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html