[PATCH v5 05/11] powerpc/perf: Applies counting method to monitor lockless pgtbl walks

[Leonardo Bras]

Applies the counting-based method for monitoring lockless pgtable walks on
read_user_stack_slow.

local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk,
so there is no need to repeat it here.

Variable that saves the irq mask was renamed from flags to irq_mask so it
doesn't lose meaning now it's not directly passed to local_irq_* functions.

Signed-off-by: Leonardo Bras <leona...@linux.ibm.com>
---
 arch/powerpc/perf/callchain.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index c84bbd4298a0..43e49d8be344 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -116,14 +116,14 @@ static int read_user_stack_slow(void __user *ptr, void 
*buf, int nb)
        unsigned shift;
        unsigned long addr = (unsigned long) ptr;
        unsigned long offset;
-       unsigned long pfn, flags;
+       unsigned long pfn, irq_mask;
        void *kaddr;
 
        pgdir = current->mm->pgd;
        if (!pgdir)
                return -EFAULT;
 
-       local_irq_save(flags);
+       irq_mask = begin_lockless_pgtbl_walk(current->mm);
        ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
        if (!ptep)
                goto err_out;
@@ -145,7 +145,7 @@ static int read_user_stack_slow(void __user *ptr, void 
*buf, int nb)
        memcpy(buf, kaddr + offset, nb);
        ret = 0;
 err_out:
-       local_irq_restore(flags);
+       end_lockless_pgtbl_walk(current->mm, irq_mask);
        return ret;
 }
 
-- 
2.20.1