On Fri, Jul 7, 2023 at 10:03 AM Axel Rasmussen axelrasmussen@google.com wrote:
On Fri, Jul 7, 2023 at 6:42 AM Peter Xu peterx@redhat.com wrote:
On Thu, Jul 06, 2023 at 03:50:35PM -0700, Axel Rasmussen wrote:
@@ -247,9 +245,13 @@ static int userfaultfd_stress(void) { void *area; unsigned long nr;
struct uffd_args args[nr_cpus];
struct uffd_args *args; uint64_t mem_size = nr_pages * page_size;args = calloc(nr_cpus, sizeof(struct uffd_args));if (!args)err("allocating args array failed");This is trivial, but I think I requested a "free" (or keep it allocate on stack) in previous version but it didn't get a response on why we cannot and it kept going.. could you help explain?
Oh, sorry! I had meant to change this after our discussion, and simply overlooked it while reworking the patches.
I'll include this change in a v4 which also addresses e.g. the comments on commit 1.
Ah, so I tried switching back to the {0} initializer, and was reminded why I didn't do that in v1. :) Ignoring the missing braces warning I talked about before, using {0} here is actually an error ("variable-sized object may not be initialized") because this is a variable sized array (nr_cpus isn't constant). So, that option is out.
I'm not a huge fan of adding the free() cleanup and dealing with all of the err() calls this function has.
Originally I switched to calloc() because I'm not a big fan of VLAs anyway. But, as a compromise in v4 I'll leave it a VLA, and switch to memset() for initializing it.
-- Peter Xu