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    Subject[PATCH v5 2/8] vmcore: clean up read_vmcore()
    Date
    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@jp.fujitsu.com>
    ---

    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 69e1198..48886e6 100644
    --- a/fs/proc/vmcore.c
    +++ b/fs/proc/vmcore.c
    @@ -119,27 +119,6 @@ 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.
    */
    @@ -148,8 +127,8 @@ 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;
    @@ -175,33 +154,26 @@ 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;
    + 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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