On Thu, Sep 20, 2012 at 05:06:32PM -0700, Tejun Heo wrote:
> Hello,
>
> On Mon, Sep 10, 2012 at 05:22:26PM -0700, Kent Overstreet wrote:
> > +void bio_copy_data(struct bio *dst, struct bio *src)
> > +{
> ...
> > + src_p = kmap_atomic(src_bv->bv_page);
> > + dst_p = kmap_atomic(dst_bv->bv_page);
> > +
> > + memcpy(dst_p + dst_bv->bv_offset,
> > + src_p + src_bv->bv_offset,
> > + bytes);
> > +
> > + kunmap_atomic(dst_p);
> > + kunmap_atomic(src_p);
>
> Wrap these in preempt_disable/enable() to allow the function to be
> called from any context?
I checked the implementation of kmap_atomic(), it already does
preempt_disable() so it's safe in process context - if I understand
correctly it needs local_irq_save()/restore() to be safe in any context
and I figured calling this from irq context is not the norm so that
should be the caller's responsibility.
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