于 2013年05月15日 17:05, HATAYAMA Daisuke 写道:
> Rewrite part of read_vmcore() that reads objects in vmcore_list in the
> same way as part reading ELF headers, by which some duplicated and
> redundant codes are removed.
>
> Signed-off-by: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
> Acked-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
This cleanup really makes the code more clear.
Just one minor nitpick below.
Acked-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
> ---
>
> fs/proc/vmcore.c | 68 ++++++++++++++++--------------------------------------
> 1 files changed, 20 insertions(+), 48 deletions(-)
>
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index 17f7e08..ab0c92e 100644
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -118,27 +118,6 @@ static ssize_t read_from_oldmem(char *buf, size_t count,
> return read;
> }
>
> -/* Maps vmcore file offset to respective physical address in memroy. */
> -static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list,
> - struct vmcore **m_ptr)
> -{
> - struct vmcore *m;
> - u64 paddr;
> -
> - list_for_each_entry(m, vc_list, list) {
> - u64 start, end;
> - start = m->offset;
> - end = m->offset + m->size - 1;
> - if (offset >= start && offset <= end) {
> - paddr = m->paddr + offset - start;
> - *m_ptr = m;
> - return paddr;
> - }
> - }
> - *m_ptr = NULL;
> - return 0;
> -}
> -
> /* Read from the ELF header and then the crash dump. On error, negative value is
> * returned otherwise number of bytes read are returned.
> */
> @@ -147,8 +126,8 @@ 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;
> + u64 start;
> + struct vmcore *m = NULL;
>
> if (buflen == 0 || *fpos >= vmcore_size)
> return 0;
> @@ -174,33 +153,26 @@ 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;
> -
> - while (buflen) {
> - tsz = min_t(size_t, buflen, PAGE_SIZE - (start & ~PAGE_MASK));
> -
> - /* Calculate left bytes in current memory segment. */
> - nr_bytes = (curr_m->size - (start - curr_m->paddr));
> - if (tsz > nr_bytes)
> - tsz = nr_bytes;
> -
> - 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;
if (tsz > buflen)
tsz = buflen;
seems better.
Or you can use a min_t here:
tsz = min_t(size_t, m->offset + m->size - *fpos, buflen);
> + start = m->paddr + *fpos - m->offset;
> + tmp = read_from_oldmem(buffer, tsz, &start, 1);
> + if (tmp < 0)
> + return tmp;
> + buflen -= tsz;
> + *fpos += tsz;
> + buffer += tsz;
> + acc += tsz;
> +
> + /* leave now if filled buffer already */
> + if (buflen == 0)
> + return acc;
> }
> }
> +
> return acc;
> }
>
>
>
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