Re: [PATCH] target/s390x/arch_dump: Simplify memory allocation in s390x_write_elf64_notes()

[Thomas Huth]

On 15/02/2023 06.48, Thomas Huth wrote:
> We are not on a hot path here, so there is no real need for the logic
> here with the split heap and stack space allocation. Simplify it by
> always allocating memory from the heap.
>
> Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>   Based-on: <20230214141056.680969-1-thuth@redhat.com>
>
>   target/s390x/arch_dump.c | 20 ++++++--------------
>   1 file changed, 6 insertions(+), 14 deletions(-)
>
> diff --git a/target/s390x/arch_dump.c b/target/s390x/arch_dump.c
> index a7c44ba49d..84e17effda 100644
> --- a/target/s390x/arch_dump.c
> +++ b/target/s390x/arch_dump.c
> @@ -227,25 +227,23 @@ static int s390x_write_elf64_notes(const char *note_name,
>                                          DumpState *s,
>                                          const NoteFuncDesc *funcs)
>   {
> -    Note note, *notep;
> +    g_autofree Note *notep = NULL;
>       const NoteFuncDesc *nf;
> -    int note_size, content_size;
> +    int note_size, prev_size = 0, content_size;
>       int ret = -1;
>   
> -    assert(strlen(note_name) < sizeof(note.name));
> +    assert(strlen(note_name) < sizeof(notep->name));
>   
>       for (nf = funcs; nf->note_contents_func; nf++) {
> -        notep = &note;
>           if (nf->pvonly && !s390_is_pv()) {
>               continue;
>           }
>   
>           content_size = nf->note_size_func ? nf->note_size_func() : nf->contents_size;
> -        note_size = sizeof(note) - sizeof(notep->contents) + content_size;
> +        note_size = sizeof(Note) - sizeof(notep->contents) + content_size;
>   
> -        /* Notes with dynamic sizes need to allocate a note */
> -        if (nf->note_size_func) {
> -            notep = g_malloc(note_size);
> +        if (prev_size < note_size) {
> +            notep = g_realloc(notep, note_size);
>           }

-ENOTENOUGHCOFFEEYET

Janosch just told me that there is a prev_size = note_size missing here ... 
sorry for that, I'll send a v2.

 Thomas