thp: change pmd_trans_huge_lock() interface to return ptl

After THP refcounting rework we have only two possible return values
from pmd_trans_huge_lock(): success and failure.  Return-by-pointer for
ptl doesn't make much sense in this case.

Let's convert pmd_trans_huge_lock() to return ptl on success and NULL on
failure.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 71ffc91060f6..85d16c67c33e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -602,7 +602,8 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
         pte_t *pte;
         spinlock_t *ptl;
 
-        if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
+        ptl = pmd_trans_huge_lock(pmd, vma);
+        if (ptl) {
                 smaps_pmd_entry(pmd, addr, walk);
                 spin_unlock(ptl);
                 return 0;
@@ -913,7 +914,8 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
         spinlock_t *ptl;
         struct page *page;
 
-        if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
+        ptl = pmd_trans_huge_lock(pmd, vma);
+        if (ptl) {
                 if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
                         clear_soft_dirty_pmd(vma, addr, pmd);
                         goto out;
@@ -1187,7 +1189,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
         int err = 0;
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-        if (pmd_trans_huge_lock(pmdp, vma, &ptl)) {
+        ptl = pmd_trans_huge_lock(pmdp, vma);
+        if (ptl) {
                 u64 flags = 0, frame = 0;
                 pmd_t pmd = *pmdp;
 
@@ -1519,7 +1522,8 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
         pte_t *orig_pte;
         pte_t *pte;
 
-        if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
+        ptl = pmd_trans_huge_lock(pmd, vma);
+        if (ptl) {
                 pte_t huge_pte = *(pte_t *)pmd;
                 struct page *page;