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Re: [Xen-devel] [PATCH v3 10/12] livepatch: Handle arbitrary size names with the list operation





On 17. Sep 2019, at 10:27, Jan Beulich <jbeulich@xxxxxxxx> wrote:

On 16.09.2019 12:59, Pawel Wieczorkiewicz wrote:
@@ -951,11 +952,13 @@ struct xen_sysctl_livepatch_list {
                                               amount of payloads and version.
                                               OUT: How many payloads left. */
    uint32_t pad;                           /* IN: Must be zero. */
+    uint64_t name_total_size;               /* OUT: Total size of all transfer names */

Why uint64_t and not uint32_t? You don't expect this to grow
beyond 4GiB, do you?

I don’t, but uint32_t is not really compatible with size_t.
And I was thought to always use size_t compatible types for sizes.

Anyway, I do not mind changing this to whatever type you prefer.


And why OUT rather than IN/OUT? Once you make this "arbitrary
size", I don't see a need for limiting this to ...

    XEN_GUEST_HANDLE_64(xen_livepatch_status_t) status;  /* OUT. Must have enough
                                               space allocate for nr of them. */
    XEN_GUEST_HANDLE_64(char) name;         /* OUT: Array of names. Each member
-                                               MUST XEN_LIVEPATCH_NAME_SIZE in size.
-                                               Must have nr of them. */
+                                               may have an arbitrary length up to
+                                               XEN_LIVEPATCH_NAME_SIZE bytes. Must have
+                                               nr of them. */

... XEN_LIVEPATCH_NAME_SIZE bytes per entry.

Changing the upper bound limitation will break certain assumptions and I did not want to pile all these on top of the current change.
But, yes, the upper bound limit could be dropped. I would prefer to do it as an independent patch.


And finally - please send to the list just once, i.e. please
don't have two xen-devel@ in the recipients list.


Sorry, I did not notice the add_maintainers.pl script adds an explicit To: for the xen-devel@.

Jan

Best Regards,
Pawel Wieczorkiewicz






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