1 /* 2 * Hypervisor filesystem for Linux on s390 - debugfs interface 3 * 4 * Copyright IBM Corp. 2010 5 * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com> 6 */ 7 8 #include <linux/slab.h> 9 #include "hypfs.h" 10 11 static struct dentry *dbfs_dir; 12 13 static struct hypfs_dbfs_data *hypfs_dbfs_data_alloc(struct hypfs_dbfs_file *f) 14 { 15 struct hypfs_dbfs_data *data; 16 17 data = kmalloc(sizeof(*data), GFP_KERNEL); 18 if (!data) 19 return NULL; 20 kref_init(&data->kref); 21 data->dbfs_file = f; 22 return data; 23 } 24 25 static void hypfs_dbfs_data_free(struct kref *kref) 26 { 27 struct hypfs_dbfs_data *data; 28 29 data = container_of(kref, struct hypfs_dbfs_data, kref); 30 data->dbfs_file->data_free(data->buf_free_ptr); 31 kfree(data); 32 } 33 34 static void data_free_delayed(struct work_struct *work) 35 { 36 struct hypfs_dbfs_data *data; 37 struct hypfs_dbfs_file *df; 38 39 df = container_of(work, struct hypfs_dbfs_file, data_free_work.work); 40 mutex_lock(&df->lock); 41 data = df->data; 42 df->data = NULL; 43 mutex_unlock(&df->lock); 44 kref_put(&data->kref, hypfs_dbfs_data_free); 45 } 46 47 static ssize_t dbfs_read(struct file *file, char __user *buf, 48 size_t size, loff_t *ppos) 49 { 50 struct hypfs_dbfs_data *data; 51 struct hypfs_dbfs_file *df; 52 ssize_t rc; 53 54 if (*ppos != 0) 55 return 0; 56 57 df = file_inode(file)->i_private; 58 mutex_lock(&df->lock); 59 if (!df->data) { 60 data = hypfs_dbfs_data_alloc(df); 61 if (!data) { 62 mutex_unlock(&df->lock); 63 return -ENOMEM; 64 } 65 rc = df->data_create(&data->buf, &data->buf_free_ptr, 66 &data->size); 67 if (rc) { 68 mutex_unlock(&df->lock); 69 kfree(data); 70 return rc; 71 } 72 df->data = data; 73 schedule_delayed_work(&df->data_free_work, HZ); 74 } 75 data = df->data; 76 kref_get(&data->kref); 77 mutex_unlock(&df->lock); 78 79 rc = simple_read_from_buffer(buf, size, ppos, data->buf, data->size); 80 kref_put(&data->kref, hypfs_dbfs_data_free); 81 return rc; 82 } 83 84 static const struct file_operations dbfs_ops = { 85 .read = dbfs_read, 86 .llseek = no_llseek, 87 }; 88 89 int hypfs_dbfs_create_file(struct hypfs_dbfs_file *df) 90 { 91 df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df, 92 &dbfs_ops); 93 if (IS_ERR(df->dentry)) 94 return PTR_ERR(df->dentry); 95 mutex_init(&df->lock); 96 INIT_DELAYED_WORK(&df->data_free_work, data_free_delayed); 97 return 0; 98 } 99 100 void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df) 101 { 102 debugfs_remove(df->dentry); 103 } 104 105 int hypfs_dbfs_init(void) 106 { 107 dbfs_dir = debugfs_create_dir("s390_hypfs", NULL); 108 return PTR_ERR_OR_ZERO(dbfs_dir); 109 } 110 111 void hypfs_dbfs_exit(void) 112 { 113 debugfs_remove(dbfs_dir); 114 } 115