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    SubjectRe: [PATCH 10/27] modpost: traverse unresolved symbols in order
    On Sun, Apr 24, 2022 at 12:09 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
    >
    > Currently, modpost manages unresolved in a singly liked list; it adds

    s/liked/linked/

    > a new node to the head, and traverses the list from new to old.
    >
    > Use a doubly linked list to keep the order in the symbol table in the
    > ELF file.
    >
    > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
    > ---
    >
    > scripts/mod/modpost.c | 20 ++++++++++++++------
    > scripts/mod/modpost.h | 2 +-
    > 2 files changed, 15 insertions(+), 7 deletions(-)
    >
    > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
    > index 1c7d2831e89d..e1eb188d6282 100644
    > --- a/scripts/mod/modpost.c
    > +++ b/scripts/mod/modpost.c
    > @@ -185,6 +185,8 @@ static struct module *new_module(const char *modname)
    > mod = NOFAIL(malloc(sizeof(*mod) + strlen(modname) + 1));
    > memset(mod, 0, sizeof(*mod));
    >
    > + INIT_LIST_HEAD(&mod->unresolved_symbols);
    > +
    > strcpy(mod->name, modname);
    > mod->is_vmlinux = (strcmp(modname, "vmlinux") == 0);
    > mod->gpl_compatible = true;
    > @@ -201,6 +203,7 @@ static struct module *new_module(const char *modname)
    >
    > struct symbol {
    > struct symbol *next;
    > + struct list_head list;

    Isn't `list` meant to replace `next`?

    > struct module *module;
    > unsigned int crc;
    > bool crc_valid;
    > @@ -255,8 +258,12 @@ static struct symbol *new_symbol(const char *name, struct module *module,
    >
    > static void sym_add_unresolved(const char *name, struct module *mod, bool weak)
    > {
    > - mod->unres = alloc_symbol(name, mod->unres);
    > - mod->unres->weak = weak;
    > + struct symbol *sym;
    > +
    > + sym = alloc_symbol(name, NULL);
    > + sym->weak = weak;
    > +
    > + list_add_tail(&sym->list, &mod->unresolved_symbols);

    Because I was curious here why NULL was passed, rather than remove the
    assignment to struct symbol's next member in alloc_symbol.

    I get why you replace the `unres` member of struct module. I guess I'm
    curious then why yet another list is added to struct symbol, rather
    than replace the next member.

    Also, does adding a struct list_head member really not specify the
    _type_ of the next element? I guess when I look at the definition of
    struct module, at the member unresolved symbols, I don't know whether
    it's a list of struct module* or a list of struct symbol*.

    <snip>

    > diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
    > index c3b5d2f0e2bb..6a90bfc08458 100644
    > --- a/scripts/mod/modpost.h
    > +++ b/scripts/mod/modpost.h
    > @@ -117,7 +117,7 @@ struct namespace_list {
    > struct module {
    > struct list_head list;
    > int gpl_compatible;
    > - struct symbol *unres;
    > + struct list_head unresolved_symbols;
    > bool from_dump; /* true if module was loaded from *.symvers */
    > bool is_vmlinux;
    > bool seen;
    > --
    > 2.32.0
    >


    --
    Thanks,
    ~Nick Desaulniers

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