unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
1
Fork 0
Code Pull requests 5 Wiki Activity

uprobes: Remove now-redundant smp_read_barrier_depends()

Browse source 
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>
This commit is contained in:
Paul E. McKenney 2017-10-09 11:08:53 -07:00
parent 98b2273784
commit 5c6338b487
1 changed files with 6 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
kernel/events/uprobes.c
View file

@ -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;