On Thu, 27 Jun 2013 16:23:34 -0400
Vivek Goyal <vgoyal at redhat.com> wrote:
> On Thu, Jun 27, 2013 at 03:32:02PM -0400, Vivek Goyal wrote:
> > On Fri, Jun 21, 2013 at 04:17:03PM +0200, Michael Holzheu wrote:
> > > On Fri, 14 Jun 2013 14:54:02 -0400
> > > Vivek Goyal <vgoyal at redhat.com> wrote:
[snip]
> Thinking more about it, I think let us cleanup with this little ugly
> bit too so that future changes become easy.
>
> Current convention is that elfcorehdr_addr and elfcorehdr_size are
> already set by arch code by the time vmcore.c starts reading it. Can't
> s390 allocate elf headers in early boot code and elfcorehdr_addr? Then
> we don't have to call elfcorehdr_alloc().
>
> And once we are done with reading headers, we can call elfcorehdr_free()
> and s390 could free memory and set elfcorehdr_addr to ELFCORE_ADDR_ERR
> and elfcorehdr_size=0. That would signify that one can not try to read
> elf headers now and it must have been freed.
>
> is_kdump_kernel() will continue to work as elfcorehdr_addr is
> ELFCORE_ADDR_ERR. And that will mean that either elfcorehdr were not
> readable/usable to begin with or they have been freed now.
Hello Vivek,
We would like to keep the alloc/free symmetry as you have suggested in a
previous mail. This also has the advantage that we do not have to rely
on the ordering of init calls.
Wouldn't it be sufficient to just set elfcorehdr_addr to ELFCORE_ADDR_ERR
after elfcorehdr_free() and remove the comment?
So the code would look like the following:
static int __init vmcore_init(void)
{
int rc = 0;
/* Allow architectures to allocate ELF header in 2nd kernel */
rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size);
if (rc)
return rc;
/*
* If elfcorehdr= has been passed in cmdline or created in 2nd kernel,
* then capture the dump.
*/
if (!(is_vmcore_usable()))
return rc;
rc = parse_crash_elf_headers();
if (rc) {
pr_warn("Kdump: vmcore not initialized\n");
return rc;
}
elfcorehdr_free(elfcorehdr_addr);
elfcorehdr_addr = ELFCORE_ADDR_ERR;
proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
if (proc_vmcore)
proc_vmcore->size = vmcore_size;
return 0;
}
This looks clean for me.
What do you think?
Best Regards,
Michael
