[Skiboot] [PATCH] core/cpu: Fix memory allocation for job array

[Oliver]

On Sun, Sep 2, 2018 at 7:59 PM, Vaidyanathan Srinivasan
<svaidy at linux.vnet.ibm.com> wrote:
> fixes: 7a3f307e core/cpu: parallelise global CPU register setting jobs
>
> This bug would result in boot-hang on some configurations due to
> cpu_wait_job() endlessly waiting for the last bogus jobs[cpu->pir] pointer.

Under what circumstances does it fail? The minimum allocation block is
sizeof(long) so even with the undersized allocation it I would expect
it to still work. I might be missing something.

> Reported-by: Stephanie Swanson <swanman at us.ibm.com>
> Reported-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
> Signed-off-by: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
> ---
>  core/cpu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/core/cpu.c b/core/cpu.c
> index 88477f82..cc5fba32 100644
> --- a/core/cpu.c
> +++ b/core/cpu.c
> @@ -1373,7 +1373,7 @@ static int64_t cpu_change_all_hid0(struct hid0_change_req *req)
>         struct cpu_thread *cpu;
>         struct cpu_job **jobs;
>
> -       jobs = zalloc(sizeof(struct cpu_job *) * cpu_max_pir + 1);
> +       jobs = zalloc(sizeof(struct cpu_job *) * (cpu_max_pir + 1));

Looks like this code was copied and pasted form cpu_cleanup_all()
since the same bug exists there. Can you add a fix there too?

We might want to just refactor this so that we have a common
cpu_run_on_all() or something. I'm not too bothered though.

>         assert(jobs);
>
>         for_each_available_cpu(cpu) {
> --
> 2.17.1
>
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