Messages in this thread | | | Date | Fri, 10 Jun 2016 14:26:18 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] events/uprobes: move smp_read_barrier_depends() where needed |
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On 06/10, Oleg Nesterov wrote: > > On 06/09, Andrea Parri wrote: > > > > There is no need to use the barrier if there is no dereference/ > > memory access; move it where needed (currently, affecting only > > Alpha). > > OK, although area == NULL is unlikely case, > > > While touching this, also make the reads _ONCE(). > > Why? both xol_area/vaddr can't change.
and perhaps it would be better to eliminate this smp_read_barrier_depends() altogether, we have a lot of helpers. I mean,
static unsigned long get_trampoline_vaddr(void) { struct xol_area *area;
area = lockless_dereference(current->mm->uprobes_state.xol_area); if (area) return area->vaddr; return -1; }
looks a bit more simple/clean. Note also another smp_read_barrier_depends() in get_xol_area() which can be changed the same way.
What do you think?
Oleg.
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