diff options
| -rw-r--r-- | fs/kernfs/file.c | 51 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 1 |
2 files changed, 30 insertions, 22 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 7247252ee9b1..e1574008adc9 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -190,15 +190,16 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, char *buf; buf = of->prealloc_buf; - if (!buf) + if (buf) + mutex_lock(&of->prealloc_mutex); + else buf = kmalloc(len, GFP_KERNEL); if (!buf) return -ENOMEM; /* * @of->mutex nests outside active ref and is used both to ensure that - * the ops aren't called concurrently for the same open file, and - * to provide exclusive access to ->prealloc_buf (when that exists). + * the ops aren't called concurrently for the same open file. */ mutex_lock(&of->mutex); if (!kernfs_get_active(of->kn)) { @@ -214,21 +215,23 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, else len = -EINVAL; + kernfs_put_active(of->kn); + mutex_unlock(&of->mutex); + if (len < 0) - goto out_unlock; + goto out_free; if (copy_to_user(user_buf, buf, len)) { len = -EFAULT; - goto out_unlock; + goto out_free; } *ppos += len; - out_unlock: - kernfs_put_active(of->kn); - mutex_unlock(&of->mutex); out_free: - if (buf != of->prealloc_buf) + if (buf == of->prealloc_buf) + mutex_unlock(&of->prealloc_mutex); + else kfree(buf); return len; } @@ -284,15 +287,22 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf, } buf = of->prealloc_buf; - if (!buf) + if (buf) + mutex_lock(&of->prealloc_mutex); + else buf = kmalloc(len + 1, GFP_KERNEL); if (!buf) return -ENOMEM; + if (copy_from_user(buf, user_buf, len)) { + len = -EFAULT; + goto out_free; + } + buf[len] = '\0'; /* guarantee string termination */ + /* * @of->mutex nests outside active ref and is used both to ensure that - * the ops aren't called concurrently for the same open file, and - * to provide exclusive access to ->prealloc_buf (when that exists). + * the ops aren't called concurrently for the same open file. */ mutex_lock(&of->mutex); if (!kernfs_get_active(of->kn)) { @@ -301,26 +311,22 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf, goto out_free; } - if (copy_from_user(buf, user_buf, len)) { - len = -EFAULT; - goto out_unlock; - } - buf[len] = '\0'; /* guarantee string termination */ - ops = kernfs_ops(of->kn); if (ops->write) len = ops->write(of, buf, len, *ppos); else len = -EINVAL; + kernfs_put_active(of->kn); + mutex_unlock(&of->mutex); + if (len > 0) *ppos += len; -out_unlock: - kernfs_put_active(of->kn); - mutex_unlock(&of->mutex); out_free: - if (buf != of->prealloc_buf) + if (buf == of->prealloc_buf) + mutex_unlock(&of->prealloc_mutex); + else kfree(buf); return len; } @@ -687,6 +693,7 @@ static int kernfs_fop_open(struct inode *inode, struct file *file) error = -ENOMEM; if (!of->prealloc_buf) goto err_free; + mutex_init(&of->prealloc_mutex); } /* diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index c06c44242f39..d306e282bb1d 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -177,6 +177,7 @@ struct kernfs_open_file { /* private fields, do not use outside kernfs proper */ struct mutex mutex; + struct mutex prealloc_mutex; int event; struct list_head list; char *prealloc_buf; |