mm/vma: small VMA lock cleanups

We declare vma_start_read() as a static function in mm/mmap_lock.c, so
there is no need to provide a stub for !CONFIG_PER_VMA_LOCK.

__is_vma_write_locked() is declared in a header and should therefore be
static inline.

Put parens around (refcnt & VMA_LOCK_OFFSET) in is_vma_writer_only() to
make precedence clear.

Link: https://lkml.kernel.org/r/20251024090902.1118174-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 2c9fffa58714f2a711474581f95afef94a3c8a01..e05da70dc0cb316fc7b9df00aea59d6d5610a3fd 100644 (file)
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -130,7 +130,7 @@ static inline bool is_vma_writer_only(int refcnt)
         * a detached vma happens only in vma_mark_detached() and is a rare
         * case, therefore most of the time there will be no unnecessary wakeup.
         */
-       return refcnt & VMA_LOCK_OFFSET && refcnt <= VMA_LOCK_OFFSET + 1;
+       return (refcnt & VMA_LOCK_OFFSET) && refcnt <= VMA_LOCK_OFFSET + 1;
 }
 
 static inline void vma_refcount_put(struct vm_area_struct *vma)
@@ -183,7 +183,7 @@ static inline void vma_end_read(struct vm_area_struct *vma)
 }
 
 /* WARNING! Can only be used if mmap_lock is expected to be write-locked */
-static bool __is_vma_write_locked(struct vm_area_struct *vma, unsigned int *mm_lock_seq)
+static inline bool __is_vma_write_locked(struct vm_area_struct *vma, unsigned int *mm_lock_seq)
 {
        mmap_assert_write_locked(vma->vm_mm);
 
@@ -281,9 +281,6 @@ static inline bool mmap_lock_speculate_retry(struct mm_struct *mm, unsigned int
        return true;
 }
 static inline void vma_lock_init(struct vm_area_struct *vma, bool reset_refcnt) {}
-static inline struct vm_area_struct *vma_start_read(struct mm_struct *mm,
-                                                   struct vm_area_struct *vma)
-               { return NULL; }
 static inline void vma_end_read(struct vm_area_struct *vma) {}
 static inline void vma_start_write(struct vm_area_struct *vma) {}
 static inline void vma_assert_write_locked(struct vm_area_struct *vma)