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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-10-09 11:08:53 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-12-04 10:52:55 -0800
commit5c6338b4877038d28148fcfe1e7f862970ebaad1 (patch)
tree38ed99c3d851c3d82efb1d9e02322ea80dd73122 /kernel/events/uprobes.c
parent98b22737847cc015a797567e32d0a4826003afbf (diff)
downloadlinux-5c6338b4877038d28148fcfe1e7f862970ebaad1.tar.bz2
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: Paul 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>
Diffstat (limited to 'kernel/events/uprobes.c')
-rw-r--r--kernel/events/uprobes.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 267f6ef91d97..ce6848e46e94 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -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;