On Fri 2006-09-29 01:35:33, Rafael J. Wysocki wrote:
> On Friday, 29 September 2006 01:03, Pavel Machek wrote:
> > Hi!
> >
> > > On Fri, 29 Sep 2006 00:13:38 +0200
> > > "Rafael J. Wysocki" <[email protected]> wrote:
> > >
> > > > To be able to use swap files as suspend storage from the userland suspend
> > > > tools we need an additional ioctl() that will allow us to provide the kernel
> > > > with both the swap header's offset and the identification of the resume
> > > > partition.
> > > >
> > > > The new ioctl() should be regarded as a replacement for the
> > > > SNAPSHOT_SET_SWAP_FILE ioctl() that from now on will be considered as
> > > > obsolete, but has to stay for backwards compatibility of the interface.
> > > >
> > > > +
> > > > +/*
> > > > + * This structure is used to pass the values needed for the identification
> > > > + * of the resume swap area from a user space to the kernel via the
> > > > + * SNAPSHOT_SET_SWAP_AREA ioctl
> > > > + */
> > > > +struct resume_swap_area {
> > > > + u_int16_t dev;
> > > > + loff_t offset;
> > > > +} __attribute__((packed));
> >
> > >
> > > hmm. Asking the compiler to pack 16-bit and 64-bit quantities in this
> > > manner is a bit risky. I guess it'll do the right thing, consistently,
> > > across all compiler versions and vendors and 32-bit-on-64-bit-kernel, etc.
> > >
> > > But from a defensiveness/paranoia POV it'd be better to use a u32 here, I
> > > suspect. (Will access to that loff_t cause an alignment trap on ia64? Any
> > > other CPUs? Dunno).
> >
> > Perhaps just loff_t offset; u32 dev; ? If 64-bit variable is first, we
> > should avoid most problems, no?
>
> Done. Updated patch follows.
Looks okay to me.
> Greetings,
> Rafael
>
>
> ---
> To be able to use swap files as suspend storage from the userland suspend
> tools we need an additional ioctl() that will allow us to provide the kernel
> with both the swap header's offset and the identification of the resume
> partition.
>
> The new ioctl() should be regarded as a replacement for the
> SNAPSHOT_SET_SWAP_FILE ioctl() that from now on will be considered as
> obsolete, but has to stay for backwards compatibility of the interface.
>
> Signed-off-by: Rafael J. Wysocki <[email protected]>
> ---
> kernel/power/power.h | 13 ++++++++++++-
> kernel/power/user.c | 31 +++++++++++++++++++++++++++++++
> 2 files changed, 43 insertions(+), 1 deletion(-)
>
> Index: linux-2.6.18-mm2/kernel/power/power.h
> ===================================================================
> --- linux-2.6.18-mm2.orig/kernel/power/power.h
> +++ linux-2.6.18-mm2/kernel/power/power.h
> @@ -119,7 +119,18 @@ extern int snapshot_image_loaded(struct
> #define SNAPSHOT_SET_SWAP_FILE _IOW(SNAPSHOT_IOC_MAGIC, 10, unsigned int)
> #define SNAPSHOT_S2RAM _IO(SNAPSHOT_IOC_MAGIC, 11)
> #define SNAPSHOT_PMOPS _IOW(SNAPSHOT_IOC_MAGIC, 12, unsigned int)
> -#define SNAPSHOT_IOC_MAXNR 12
> +#define SNAPSHOT_SET_SWAP_AREA _IOW(SNAPSHOT_IOC_MAGIC, 13, void *)
> +#define SNAPSHOT_IOC_MAXNR 13
> +
> +/*
> + * This structure is used to pass the values needed for the identification
> + * of the resume swap area from a user space to the kernel via the
> + * SNAPSHOT_SET_SWAP_AREA ioctl
> + */
> +struct resume_swap_area {
> + loff_t offset;
> + u_int32_t dev;
> +} __attribute__((packed));
>
> #define PMOPS_PREPARE 1
> #define PMOPS_ENTER 2
> Index: linux-2.6.18-mm2/kernel/power/user.c
> ===================================================================
> --- linux-2.6.18-mm2.orig/kernel/power/user.c
> +++ linux-2.6.18-mm2/kernel/power/user.c
> @@ -343,6 +343,37 @@ OutS3:
> }
> break;
>
> + case SNAPSHOT_SET_SWAP_AREA:
> + if (data->bitmap) {
> + error = -EPERM;
> + } else {
> + struct resume_swap_area swap_area;
> + dev_t swdev;
> +
> + error = copy_from_user(&swap_area, (void __user *)arg,
> + sizeof(struct resume_swap_area));
> + if (error) {
> + error = -EFAULT;
> + break;
> + }
> +
> + /*
> + * User space encodes device types as two-byte values,
> + * so we need to recode them
> + */
> + swdev = old_decode_dev(swap_area.dev);
> + if (swdev) {
> + offset = swap_area.offset;
> + data->swap = swap_type_of(swdev, offset);
> + if (data->swap < 0)
> + error = -ENODEV;
> + } else {
> + data->swap = -1;
> + error = -EINVAL;
> + }
> + }
> + break;
> +
> default:
> error = -ENOTTY;
>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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