diff options
Diffstat (limited to 'fs/kernfs/file.c')
| -rw-r--r-- | fs/kernfs/file.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 4a5863b79de9..fa053151fa96 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -421,6 +421,16 @@ static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma) const struct kernfs_ops *ops; int rc; + /* + * mmap path and of->mutex are prone to triggering spurious lockdep + * warnings and we don't want to add spurious locking dependency + * between the two. Check whether mmap is actually implemented + * without grabbing @of->mutex by testing HAS_MMAP flag. See the + * comment in kernfs_file_open() for more details. + */ + if (!(of->sd->s_flags & SYSFS_FLAG_HAS_MMAP)) + return -ENODEV; + mutex_lock(&of->mutex); rc = -ENODEV; @@ -428,10 +438,7 @@ static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma) goto out_unlock; ops = kernfs_ops(of->sd); - if (ops->mmap) - rc = ops->mmap(of, vma); - if (rc) - goto out_put; + rc = ops->mmap(of, vma); /* * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup() @@ -596,6 +603,9 @@ static int kernfs_file_open(struct inode *inode, struct file *file) * happen on the same file. At this point, we can't easily give * each file a separate locking class. Let's differentiate on * whether the file has mmap or not for now. + * + * Both paths of the branch look the same. They're supposed to + * look that way and give @of->mutex different static lockdep keys. */ if (has_mmap) mutex_init(&of->mutex); |