svn commit: r333860 - head/sys/kern

[Matthew Macy]

Talk to the gcc devs. The warning is useful even if there are false positives.

On Wed, May 23, 2018 at 3:27 PM, Gleb Smirnoff <glebius at freebsd.org> wrote:
>   Hi,
>
> On Sat, May 19, 2018 at 05:10:52AM +0000, Matt Macy wrote:
> M> Author: mmacy
> M> Date: Sat May 19 05:10:51 2018
> M> New Revision: 333860
> M> URL: https://svnweb.freebsd.org/changeset/base/333860
> M>
> M> Log:
> M>   sendfile: annotate unused value and ensure that npages is actually initialized
> M>
> M> Modified:
> M>   head/sys/kern/kern_sendfile.c
> M>
> M> Modified: head/sys/kern/kern_sendfile.c
> M> ==============================================================================
> M> --- head/sys/kern/kern_sendfile.c    Sat May 19 05:09:10 2018        (r333859)
> M> +++ head/sys/kern/kern_sendfile.c    Sat May 19 05:10:51 2018        (r333860)
> M> @@ -341,7 +341,7 @@ sendfile_swapin(vm_object_t obj, struct sf_io *sfio, o
> M>      }
> M>
> M>      for (int i = 0; i < npages;) {
> M> -            int j, a, count, rv;
> M> +            int j, a, count, rv __unused;
> M>
> M>              /* Skip valid pages. */
> M>              if (vm_page_is_valid(pa[i], vmoff(i, off) & PAGE_MASK,
> M> @@ -688,6 +688,7 @@ retry_space:
> M>                      if (space == 0) {
> M>                              sfio = NULL;
> M>                              nios = 0;
> M> +                            npages = 0;
> M>                              goto prepend_header;
> M>                      }
> M>                      hdr_uio = NULL;
>
> This initialization is redundant and a compiler warning if exists is wrong.
>
> If we jump down to prepend_header with nios == 0, we won't ever use npages.
>
> --
> Gleb Smirnoff