Re: [PATCH v2 6/9] s390/module: Use s390_kernel_write() for late relocations

Miroslav Benes
2020-04-22T12:28:28Z

> +int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
> + unsigned int symindex, unsigned int relsec,
> + struct module *me)
> +{
> + int ret;
> + bool early = me->state == MODULE_STATE_UNFORMED;
> + void *(*write)(void *, const void *, size_t) = memcpy;
> +
> + if (!early) {
> + write = s390_kernel_write;
> + mutex_lock(&text_mutex);
> + }
> +
> + ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
> + write);
> +
> + if (!early)
> + mutex_unlock(&text_mutex);
> +
> + return ret;
> +}

It means that you can take text_mutex the second time here because it
is still taken in klp_init_object_loaded(). It is removed later in the
series though. The same applies for x86 patch.

Also, s390_kernel_write() grabs s390_kernel_write_lock spinlock before
writing anything, so maybe text_mutex is not really needed as long as
s390_kernel_write is called everywhere for text patching.

Miroslav