On 11/8/20 11:11 PM, Lukas Bulwahn wrote:
> make clang-analyzer caught my attention with:
>
> kernel/sysctl.c:1511:4: warning: Value stored to 'first' is never read \
> [clang-analyzer-deadcode.DeadStores]
> first = 0;
> ^
>
> Commit 9f977fb7ae9d ("sysctl: add proc_do_large_bitmap") introduced
> proc_do_large_bitmap(), where the variable first is only effectively used
> when write is false; when write is true, the variable first is only used in
> a dead assignment.
>
> So, simply remove this dead assignment and put the variable in local scope.
>
> As compilers will detect this unneeded assignment and optimize this anyway,
> the resulting object code is identical before and after this change.
>
> No functional change. No change to object code.
>
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
> ---
> applies cleanly on v5.10-rc3 and next-20201106
>
> Luis, Kees, Iurii, please pick this minor non-urgent clean-up patch.
>
> kernel/sysctl.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index ce75c67572b9..cc274a431d91 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1423,7 +1423,6 @@ int proc_do_large_bitmap(struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> int err = 0;
> - bool first = 1;
> size_t left = *lenp;
> unsigned long bitmap_len = table->maxlen;
> unsigned long *bitmap = *(unsigned long **) table->data;
> @@ -1508,12 +1507,12 @@ int proc_do_large_bitmap(struct ctl_table *table, int write,
> }
>
> bitmap_set(tmp_bitmap, val_a, val_b - val_a + 1);
> - first = 0;
> proc_skip_char(&p, &left, '\n');
> }
> left += skipped;
> } else {
> unsigned long bit_a, bit_b = 0;
> + bool first = 1;
This looks fine, but while you are here how about setting, to match the type
first = true
And then only clearing first once
if (!first)
proc_put_char(&buffer, &left, ',');
else
first = false
Instead of at every loop iteraction
Tom
>
> while (left) {
> bit_a = find_next_bit(bitmap, bitmap_len, bit_b);
