diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mmap_lock.h | 37 |
1 files changed, 34 insertions, 3 deletions
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 294fb282052d..1887ca55ead7 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -78,6 +78,37 @@ static inline void mmap_assert_write_locked(const struct mm_struct *mm) #ifdef CONFIG_PER_VMA_LOCK +/* + * VMA locks do not behave like most ordinary locks found in the kernel, so we + * cannot quite have full lockdep tracking in the way we would ideally prefer. + * + * Read locks act as shared locks which exclude an exclusive lock being + * taken. We therefore mark these accordingly on read lock acquire/release. + * + * Write locks are acquired exclusively per-VMA, but released in a shared + * fashion, that is upon vma_end_write_all(), we update the mmap's seqcount such + * that write lock is released. + * + * We therefore cannot track write locks per-VMA, nor do we try. Mitigating this + * is the fact that, of course, we do lockdep-track the mmap lock rwsem which + * must be held when taking a VMA write lock. + * + * We do, however, want to indicate that during either acquisition of a VMA + * write lock or detachment of a VMA that we require the lock held be exclusive, + * so we utilise lockdep to do so. + */ +#define __vma_lockdep_acquire_read(vma) \ + lock_acquire_shared(&vma->vmlock_dep_map, 0, 1, NULL, _RET_IP_) +#define __vma_lockdep_release_read(vma) \ + lock_release(&vma->vmlock_dep_map, _RET_IP_) +#define __vma_lockdep_acquire_exclusive(vma) \ + lock_acquire_exclusive(&vma->vmlock_dep_map, 0, 0, NULL, _RET_IP_) +#define __vma_lockdep_release_exclusive(vma) \ + lock_release(&vma->vmlock_dep_map, _RET_IP_) +/* Only meaningful if CONFIG_LOCK_STAT is defined. */ +#define __vma_lockdep_stat_mark_acquired(vma) \ + lock_acquired(&vma->vmlock_dep_map, _RET_IP_) + static inline void mm_lock_seqcount_init(struct mm_struct *mm) { seqcount_init(&mm->mm_lock_seq); @@ -176,9 +207,9 @@ static inline void vma_refcount_put(struct vm_area_struct *vma) struct mm_struct *mm = vma->vm_mm; int newcnt; - rwsem_release(&vma->vmlock_dep_map, _RET_IP_); - + __vma_lockdep_release_read(vma); newcnt = __vma_refcount_put_return(vma); + /* * __vma_enter_locked() may be sleeping waiting for readers to drop * their reference count, so wake it up if we were the last reader @@ -207,7 +238,7 @@ static inline bool vma_start_read_locked_nested(struct vm_area_struct *vma, int VM_REFCNT_LIMIT))) return false; - rwsem_acquire_read(&vma->vmlock_dep_map, 0, 1, _RET_IP_); + __vma_lockdep_acquire_read(vma); return true; } |