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SubjectRe: [PATCH 07/13] vmcore: modify read_vmcore() to read buffer on 2nd kernel
On Thu, Feb 14, 2013 at 07:12:21PM +0900, HATAYAMA Daisuke wrote:
> If a given vmcore object has VMCORE_2ND_KERNEL type, target data is in
> the buffer on 2nd kernel.
>

Looks like this patch is doing two things.

- Cleanup how read is performed. Get rid of map_offset_to_paddr() and
open code it and use list_for_each_entry().

- Read some memory from current kernel if VMCORE_2ND_KERNEL is set.

Can you break it down in two patches.

Thanks
Vivek

> Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
> ---
>
> fs/proc/vmcore.c | 64 ++++++++++++++++++++++++++----------------------------
> 1 files changed, 31 insertions(+), 33 deletions(-)
>
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index 77e0a0e..4125a65 100644
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -146,8 +146,7 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
> {
> ssize_t acc = 0, tmp;
> size_t tsz;
> - u64 start, nr_bytes;
> - struct vmcore *curr_m = NULL;
> + struct vmcore *m;
>
> if (buflen == 0 || *fpos >= vmcore_size)
> return 0;
> @@ -173,39 +172,38 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
> return acc;
> }
>
> - start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
> - if (!curr_m)
> - return -EINVAL;
> - if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
> - tsz = buflen;
> -
> - /* Calculate left bytes in current memory segment. */
> - nr_bytes = (curr_m->size - (start - curr_m->paddr));
> - if (tsz > nr_bytes)
> - tsz = nr_bytes;
> -
> - while (buflen) {
> - tmp = read_from_oldmem(buffer, tsz, &start, 1);
> - if (tmp < 0)
> - return tmp;
> - buflen -= tsz;
> - *fpos += tsz;
> - buffer += tsz;
> - acc += tsz;
> - if (start >= (curr_m->paddr + curr_m->size)) {
> - if (curr_m->list.next == &vmcore_list)
> - return acc; /*EOF*/
> - curr_m = list_entry(curr_m->list.next,
> - struct vmcore, list);
> - start = curr_m->paddr;
> + list_for_each_entry(m, &vmcore_list, list) {
> + if (*fpos < m->offset + m->size) {
> + tsz = m->offset + m->size - *fpos;
> + if (buflen < tsz)
> + tsz = buflen;
> + switch (m->type) {
> + case VMCORE_OLD_MEMORY: {
> + u64 paddr = m->paddr + *fpos - m->offset;
> +
> + tmp = read_from_oldmem(buffer, tsz, &paddr, 1);
> + if (tmp < 0)
> + return tmp;
> + break;
> + }
> + case VMCORE_2ND_KERNEL:
> + if (copy_to_user(buffer,
> + m->buf + (*fpos - m->offset),
> + tsz))
> + return -EFAULT;
> + break;
> + }
> + buflen -= tsz;
> + *fpos += tsz;
> + buffer += tsz;
> + acc += tsz;
> +
> + /* leave now if filled buffer already */
> + if (buflen == 0)
> + return acc;
> }
> - if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
> - tsz = buflen;
> - /* Calculate left bytes in current memory segment. */
> - nr_bytes = (curr_m->size - (start - curr_m->paddr));
> - if (tsz > nr_bytes)
> - tsz = nr_bytes;
> }
> +
> return acc;
> }
>


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