diff options
| -rw-r--r-- | include/linux/mmap_lock.h | 45 | ||||
| -rw-r--r-- | mm/mmap_lock.c | 6 |
2 files changed, 27 insertions, 24 deletions
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 678f90080fa6..1746a172a81c 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -258,21 +258,31 @@ static inline void vma_end_read(struct vm_area_struct *vma) vma_refcount_put(vma); } -/* WARNING! Can only be used if mmap_lock is expected to be write-locked */ -static inline bool __is_vma_write_locked(struct vm_area_struct *vma, unsigned int *mm_lock_seq) +static inline unsigned int __vma_raw_mm_seqnum(struct vm_area_struct *vma) { + const struct mm_struct *mm = vma->vm_mm; + + /* We must hold an exclusive write lock for this access to be valid. */ mmap_assert_write_locked(vma->vm_mm); + return mm->mm_lock_seq.sequence; +} +/* + * Determine whether a VMA is write-locked. Must be invoked ONLY if the mmap + * write lock is held. + * + * Returns true if write-locked, otherwise false. + */ +static inline bool __is_vma_write_locked(struct vm_area_struct *vma) +{ /* * current task is holding mmap_write_lock, both vma->vm_lock_seq and * mm->mm_lock_seq can't be concurrently modified. */ - *mm_lock_seq = vma->vm_mm->mm_lock_seq.sequence; - return (vma->vm_lock_seq == *mm_lock_seq); + return vma->vm_lock_seq == __vma_raw_mm_seqnum(vma); } -int __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq, - int state); +int __vma_start_write(struct vm_area_struct *vma, int state); /* * Begin writing to a VMA. @@ -281,12 +291,10 @@ int __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq, */ static inline void vma_start_write(struct vm_area_struct *vma) { - unsigned int mm_lock_seq; - - if (__is_vma_write_locked(vma, &mm_lock_seq)) + if (__is_vma_write_locked(vma)) return; - __vma_start_write(vma, mm_lock_seq, TASK_UNINTERRUPTIBLE); + __vma_start_write(vma, TASK_UNINTERRUPTIBLE); } /** @@ -305,30 +313,25 @@ static inline void vma_start_write(struct vm_area_struct *vma) static inline __must_check int vma_start_write_killable(struct vm_area_struct *vma) { - unsigned int mm_lock_seq; - - if (__is_vma_write_locked(vma, &mm_lock_seq)) + if (__is_vma_write_locked(vma)) return 0; - return __vma_start_write(vma, mm_lock_seq, TASK_KILLABLE); + + return __vma_start_write(vma, TASK_KILLABLE); } static inline void vma_assert_write_locked(struct vm_area_struct *vma) { - unsigned int mm_lock_seq; - - VM_BUG_ON_VMA(!__is_vma_write_locked(vma, &mm_lock_seq), vma); + VM_WARN_ON_ONCE_VMA(!__is_vma_write_locked(vma), vma); } static inline void vma_assert_locked(struct vm_area_struct *vma) { - unsigned int mm_lock_seq; - /* * See the comment describing the vm_area_struct->vm_refcnt field for * details of possible refcnt values. */ - VM_BUG_ON_VMA(refcount_read(&vma->vm_refcnt) <= 1 && - !__is_vma_write_locked(vma, &mm_lock_seq), vma); + VM_WARN_ON_ONCE_VMA(refcount_read(&vma->vm_refcnt) <= 1 && + !__is_vma_write_locked(vma), vma); } static inline bool vma_is_attached(struct vm_area_struct *vma) diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c index 490793ac88ed..898c2ef1e958 100644 --- a/mm/mmap_lock.c +++ b/mm/mmap_lock.c @@ -136,14 +136,14 @@ static int __vma_start_exclude_readers(struct vma_exclude_readers_state *ves) return 0; } -int __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq, - int state) +int __vma_start_write(struct vm_area_struct *vma, int state) { - int err; + const unsigned int mm_lock_seq = __vma_raw_mm_seqnum(vma); struct vma_exclude_readers_state ves = { .vma = vma, .state = state, }; + int err; err = __vma_start_exclude_readers(&ves); if (err) { |