Re: [PATCH 2/2] s390: convert to GENERIC_VDSO

Heiko Carstens
2020-08-03T18:44:46Z

On Mon, Aug 03, 2020 at 06:05:24PM +0200, Thomas Gleixner wrote:
> +/**
> + * vdso_update_begin - Start of a VDSO update section
> + *
> + * Allows architecture code to safely update the architecture specific VDSO
> + * data.
> + */
> +void vdso_update_begin(void)
> +{
> + struct vdso_data *vdata = __arch_get_k_vdso_data();
> +
> + raw_spin_lock(&timekeeper_lock);
> + vdso_write_begin(vdata);
> +}

I would assume that this only works if vdso_update_begin() is called
with irqs disabled, otherwise it could deadlock, no?

Maybe something like:

void vdso_update_begin(unsigned long *flags)
{
struct vdso_data *vdata = __arch_get_k_vdso_data();

raw_spin_lock_irqsave(&timekeeper_lock, *flags);
vdso_write_begin(vdata);
}

void vdso_update_end(unsigned long *flags)
{
struct vdso_data *vdata = __arch_get_k_vdso_data();

vdso_write_end(vdata);
__arch_sync_vdso_data(vdata);
raw_spin_unlock_irqrestore(&timekeeper_lock, *flags);
}

? Just wondering.