diff options
| -rw-r--r-- | fs/sysfs/file.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index a3a705edb19..11b970a87d0 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -663,7 +663,7 @@ static int kernfs_file_open(struct inode *inode, struct file *file) struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata; struct kobject *kobj = attr_sd->s_parent->priv; struct sysfs_open_file *of; - bool has_read, has_write; + bool has_read, has_write, has_mmap; int error = -EACCES; /* need attr_sd for attr and ops, its parent for kobj */ @@ -675,6 +675,7 @@ static int kernfs_file_open(struct inode *inode, struct file *file) has_read = battr->read || battr->mmap; has_write = battr->write || battr->mmap; + has_mmap = battr->mmap; } else { const struct sysfs_ops *ops = sysfs_file_ops(attr_sd); @@ -686,6 +687,7 @@ static int kernfs_file_open(struct inode *inode, struct file *file) has_read = ops->show; has_write = ops->store; + has_mmap = false; } /* check perms and supported operations */ @@ -703,7 +705,23 @@ static int kernfs_file_open(struct inode *inode, struct file *file) if (!of) goto err_out; - mutex_init(&of->mutex); + /* + * The following is done to give a different lockdep key to + * @of->mutex for files which implement mmap. This is a rather + * crude way to avoid false positive lockdep warning around + * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and + * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under + * which mm->mmap_sem nests, while holding @of->mutex. As each + * open file has a separate mutex, it's okay as long as those don't + * 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. + */ + if (has_mmap) + mutex_init(&of->mutex); + else + mutex_init(&of->mutex); + of->sd = attr_sd; of->file = file; |