On Tue, Oct 27, 2020 at 8:31 AM Aleksandr Nogikh [off-list ref] wrote:

On Mon, Oct 26, 2020 at 7:57 PM Willem de Bruijn
[off-list ref] wrote:
[...]

quoted

If the handle does not need to be set if zero, why then set it if the
skb has extensions?

The point of that condition is to avoid unnecessary allocations of skb extension
objects. At the same time, one would expect skb_get_kcov_handle to return the
latest value that was set via skb_set_kcov_handle. So if a buffer already has a
non-zero kcov_handle and skb_set_kcov_handle is called to set it to zero, it
should be set to zero.

I see. I thought it was some best effort approach: if there happens to
be space, use it, but don't allocate. Which I did not understand.
Could you rephrase the comment to make more clear that this is about
clearing a possibly previously set value.

quoted

skb_ext_add and skb_ext_find are not defined unless CONFIG_SKB_EXTENSIONS.

Perhaps CONFIG_KCOV should be made to select that?

Yes, thank you for pointing it out. I’ll fix it in the next version.