On Thu, Nov 18, 2010 at 03:21:05PM -0600, Nathan Lynch wrote:
> Long-running operations in the kernel should:
>
> o not monopolize the CPU
> o abort when asked
>
> Put voluntary preemption points in ckpt_kread, ckpt_kwrite, and the
> VMA-walking checkpoint code. At the same points, return an error if a
> fatal signal is pending; callers of these functions are supposed to be
> checking return values.
We do alot more than read/write the image -- e.g. collecting references at
the beginning prior to checkpoint. Perhaps should add some to the objhash
code too.
Cheers,
-Matt Helsley
>
> Signed-off-by: Nathan Lynch <ntl@xxxxxxxxx>
> ---
> kernel/checkpoint/sys.c | 10 ++++++++++
> mm/checkpoint.c | 7 +++++++
> 2 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/checkpoint/sys.c b/kernel/checkpoint/sys.c
> index b761ec0..04e6277 100644
> --- a/kernel/checkpoint/sys.c
> +++ b/kernel/checkpoint/sys.c
> @@ -72,6 +72,11 @@ int ckpt_kwrite(struct ckpt_ctx *ctx, void *addr, size_t count)
> if (ckpt_test_error(ctx))
> return ckpt_get_error(ctx);
>
> + if (fatal_signal_pending(current))
> + return -EINTR;
> +
> + cond_resched();
> +
> ret = _ckpt_kwrite(ctx->file, addr, count);
> if (ret < 0)
> return ret;
> @@ -103,6 +108,11 @@ int ckpt_kread(struct ckpt_ctx *ctx, void *addr, size_t count)
> if (ckpt_test_error(ctx))
> return ckpt_get_error(ctx);
>
> + if (fatal_signal_pending(current))
> + return -EINTR;
> +
> + cond_resched();
> +
> ret = _ckpt_kread(ctx->file, addr, count);
> if (ret < 0)
> return ret;
> diff --git a/mm/checkpoint.c b/mm/checkpoint.c
> index 70300e8..6732a2e 100644
> --- a/mm/checkpoint.c
> +++ b/mm/checkpoint.c
> @@ -310,6 +310,13 @@ static int vma_fill_pgarr(struct ckpt_ctx *ctx,
> while (addr < end) {
> struct page *page;
>
> + if (fatal_signal_pending(current)) {
> + cnt = -EINTR;
> + goto out;
> + }
> +
> + cond_resched();
> +
> if (vma)
> page = consider_private_page(vma, addr);
> else
> --
> 1.7.3.2
>
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