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Commit 5c6338b4 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

uprobes: Remove now-redundant smp_read_barrier_depends() 



Now that READ_ONCE() implies smp_read_barrier_depends(), the
get_xol_area() and get_trampoline_vaddr() no longer need their
smp_read_barrier_depends() calls, which this commit removes.
While we are here, convert the corresponding smp_wmb() to an
smp_store_release().

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
parent 98b22737

kernel/events/uprobes.c

+6 −6
Original line number Diff line number Diff line
@@ -1167,8 +1167,8 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) 
	}



	ret = 0;

	smp_wmb();	/* pairs with get_xol_area() */

	mm->uprobes_state.xol_area = area;

	/* pairs with get_xol_area() */

	smp_store_release(&mm->uprobes_state.xol_area, area); /* ^^^ */

 fail:

	up_write(&mm->mmap_sem);
@@ -1230,8 +1230,8 @@ static struct xol_area *get_xol_area(void) 
	if (!mm->uprobes_state.xol_area)

		__create_xol_area(0);



	area = mm->uprobes_state.xol_area;

	smp_read_barrier_depends();	/* pairs with wmb in xol_add_vma() */

	/* Pairs with xol_add_vma() smp_store_release() */

	area = READ_ONCE(mm->uprobes_state.xol_area); /* ^^^ */

	return area;

}
@@ -1528,8 +1528,8 @@ static unsigned long get_trampoline_vaddr(void) 
	struct xol_area *area;

	unsigned long trampoline_vaddr = -1;



	area = current->mm->uprobes_state.xol_area;

	smp_read_barrier_depends();

	/* Pairs with xol_add_vma() smp_store_release() */

	area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */

	if (area)

		trampoline_vaddr = area->vaddr;