Half dozen small cleanups plus change to allow pstore

backend drivers to be unloaded.
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Merge tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux

Pull pstore updates from Tony Luck:
 "Half dozen small cleanups plus change to allow pstore backend drivers
  to be unloaded"

* tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  pstore: fix code comment to match code
  efi-pstore: fix kernel-doc argument name
  pstore: Fix return type of pstore_is_mounted()
  pstore: add pstore unregister
  pstore: add a helper function pstore_register_kmsg
  pstore: add vmalloc error check

drivers/firmware/efi/efi-pstore.c

@@ -103,7 +103,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 
 /**
  * efi_pstore_scan_sysfs_enter
- * @entry: scanning entry
+ * @pos: scanning entry
  * @next: next entry
  * @head: list head
  */

fs/pstore/Kconfig

@@ -1,5 +1,5 @@
 config PSTORE
-	bool "Persistent store support"
+	tristate "Persistent store support"
 	default n
 	select ZLIB_DEFLATE
 	select ZLIB_INFLATE

fs/pstore/Makefile

@@ -2,12 +2,12 @@
 # Makefile for the linux pstorefs routines.
 #
 
-obj-y += pstore.o
+obj-$(CONFIG_PSTORE) += pstore.o
 
 pstore-objs += inode.o platform.o
-obj-$(CONFIG_PSTORE_FTRACE)	+= ftrace.o
+pstore-$(CONFIG_PSTORE_FTRACE)	+= ftrace.o
 
-obj-$(CONFIG_PSTORE_PMSG)	+= pmsg.o
+pstore-$(CONFIG_PSTORE_PMSG)	+= pmsg.o
 
 ramoops-objs += ram.o ram_core.o
 obj-$(CONFIG_PSTORE_RAM)	+= ramoops.o

fs/pstore/ftrace.c

@@ -104,22 +104,23 @@ static const struct file_operations pstore_knob_fops = {
 	.write	= pstore_ftrace_knob_write,
 };
 
+static struct dentry *pstore_ftrace_dir;
+
 void pstore_register_ftrace(void)
 {
-	struct dentry *dir;
 	struct dentry *file;
 
 	if (!psinfo->write_buf)
 		return;
 
-	dir = debugfs_create_dir("pstore", NULL);
-	if (!dir) {
+	pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
+	if (!pstore_ftrace_dir) {
 		pr_err("%s: unable to create pstore directory\n", __func__);
 		return;
 	}
 
-	file = debugfs_create_file("record_ftrace", 0600, dir, NULL,
-				   &pstore_knob_fops);
+	file = debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir,
+				   NULL, &pstore_knob_fops);
 	if (!file) {
 		pr_err("%s: unable to create record_ftrace file\n", __func__);
 		goto err_file;
@@ -127,5 +128,17 @@ void pstore_register_ftrace(void)
 
 	return;
 err_file:
-	debugfs_remove(dir);
+	debugfs_remove(pstore_ftrace_dir);
+}
+
+void pstore_unregister_ftrace(void)
+{
+	mutex_lock(&pstore_ftrace_lock);
+	if (pstore_ftrace_enabled) {
+		unregister_ftrace_function(&pstore_ftrace_ops);
+		pstore_ftrace_enabled = 0;
+	}
+	mutex_unlock(&pstore_ftrace_lock);
+
+	debugfs_remove_recursive(pstore_ftrace_dir);
 }

fs/pstore/inode.c

@@ -178,6 +178,7 @@ static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
 }
 
 static const struct file_operations pstore_file_operations = {
+	.owner		= THIS_MODULE,
 	.open		= pstore_file_open,
 	.read		= pstore_file_read,
 	.llseek		= pstore_file_llseek,
@@ -287,7 +288,7 @@ static const struct super_operations pstore_ops = {
 
 static struct super_block *pstore_sb;
 
-int pstore_is_mounted(void)
+bool pstore_is_mounted(void)
 {
 	return pstore_sb != NULL;
 }
@@ -456,6 +457,7 @@ static void pstore_kill_sb(struct super_block *sb)
 }
 
 static struct file_system_type pstore_fs_type = {
+	.owner          = THIS_MODULE,
 	.name		= "pstore",
 	.mount		= pstore_mount,
 	.kill_sb	= pstore_kill_sb,
@@ -479,5 +481,12 @@ out:
 }
 module_init(init_pstore_fs)
 
+static void __exit exit_pstore_fs(void)
+{
+	unregister_filesystem(&pstore_fs_type);
+	sysfs_remove_mount_point(fs_kobj, "pstore");
+}
+module_exit(exit_pstore_fs)
+
 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 MODULE_LICENSE("GPL");

fs/pstore/internal.h

@@ -41,14 +41,18 @@ pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
 
 #ifdef CONFIG_PSTORE_FTRACE
 extern void pstore_register_ftrace(void);
+extern void pstore_unregister_ftrace(void);
 #else
 static inline void pstore_register_ftrace(void) {}
+static inline void pstore_unregister_ftrace(void) {}
 #endif
 
 #ifdef CONFIG_PSTORE_PMSG
 extern void pstore_register_pmsg(void);
+extern void pstore_unregister_pmsg(void);
 #else
 static inline void pstore_register_pmsg(void) {}
+static inline void pstore_unregister_pmsg(void) {}
 #endif
 
 extern struct pstore_info *psinfo;
@@ -59,6 +63,6 @@ extern int	pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
 			      int count, char *data, bool compressed,
 			      size_t size, struct timespec time,
 			      struct pstore_info *psi);
-extern int	pstore_is_mounted(void);
+extern bool	pstore_is_mounted(void);
 
 #endif

fs/pstore/platform.c

@@ -237,6 +237,14 @@ static void allocate_buf_for_compression(void)
 
 }
 
+static void free_buf_for_compression(void)
+{
+	kfree(stream.workspace);
+	stream.workspace = NULL;
+	kfree(big_oops_buf);
+	big_oops_buf = NULL;
+}
+
 /*
  * Called when compression fails, since the printk buffer
  * would be fetched for compression calling it again when
@@ -353,6 +361,19 @@ static struct kmsg_dumper pstore_dumper = {
 	.dump = pstore_dump,
 };
 
+/*
+ * Register with kmsg_dump to save last part of console log on panic.
+ */
+static void pstore_register_kmsg(void)
+{
+	kmsg_dump_register(&pstore_dumper);
+}
+
+static void pstore_unregister_kmsg(void)
+{
+	kmsg_dump_unregister(&pstore_dumper);
+}
+
 #ifdef CONFIG_PSTORE_CONSOLE
 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 {
@@ -390,8 +411,14 @@ static void pstore_register_console(void)
 {
 	register_console(&pstore_console);
 }
+
+static void pstore_unregister_console(void)
+{
+	unregister_console(&pstore_console);
+}
 #else
 static void pstore_register_console(void) {}
+static void pstore_unregister_console(void) {}
 #endif
 
 static int pstore_write_compat(enum pstore_type_id type,
@@ -410,8 +437,6 @@ static int pstore_write_compat(enum pstore_type_id type,
  * read function right away to populate the file system. If not
  * then the pstore mount code will call us later to fill out
  * the file system.
- *
- * Register with kmsg_dump to save last part of console log on panic.
  */
 int pstore_register(struct pstore_info *psi)
 {
@@ -442,7 +467,7 @@ int pstore_register(struct pstore_info *psi)
 	if (pstore_is_mounted())
 		pstore_get_records(0);
 
-	kmsg_dump_register(&pstore_dumper);
+	pstore_register_kmsg();
 
 	if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
 		pstore_register_console();
@@ -462,12 +487,28 @@ int pstore_register(struct pstore_info *psi)
 	 */
 	backend = psi->name;
 
+	module_put(owner);
+
 	pr_info("Registered %s as persistent store backend\n", psi->name);
 
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pstore_register);
 
+void pstore_unregister(struct pstore_info *psi)
+{
+	pstore_unregister_pmsg();
+	pstore_unregister_ftrace();
+	pstore_unregister_console();
+	pstore_unregister_kmsg();
+
+	free_buf_for_compression();
+
+	psinfo = NULL;
+	backend = NULL;
+}
+EXPORT_SYMBOL_GPL(pstore_unregister);
+
 /*
  * Read all the records from the persistent store. Create
  * files in our filesystem.  Don't warn about -EEXIST errors

fs/pstore/pmsg.c

@@ -37,6 +37,8 @@ static ssize_t write_pmsg(struct file *file, const char __user *buf,
 	if (buffer_size > PMSG_MAX_BOUNCE_BUFFER_SIZE)
 		buffer_size = PMSG_MAX_BOUNCE_BUFFER_SIZE;
 	buffer = vmalloc(buffer_size);
+	if (!buffer)
+		return -ENOMEM;
 
 	mutex_lock(&pmsg_lock);
 	for (i = 0; i < count; ) {
@@ -112,3 +114,10 @@ err_class:
 err:
 	return;
 }
+
+void pstore_unregister_pmsg(void)
+{
+	device_destroy(pmsg_class, MKDEV(pmsg_major, 0));
+	class_destroy(pmsg_class);
+	unregister_chrdev(pmsg_major, PMSG_NAME);
+}

fs/pstore/ram.c

@@ -578,30 +578,27 @@ fail_out:
 	return err;
 }
 
-static int __exit ramoops_remove(struct platform_device *pdev)
+static int ramoops_remove(struct platform_device *pdev)
 {
-#if 0
-	/* TODO(kees): We cannot unload ramoops since pstore doesn't support
-	 * unregistering yet.
-	 */
 	struct ramoops_context *cxt = &oops_cxt;
 
-	iounmap(cxt->virt_addr);
-	release_mem_region(cxt->phys_addr, cxt->size);
+	pstore_unregister(&cxt->pstore);
 	cxt->max_dump_cnt = 0;
 
-	/* TODO(kees): When pstore supports unregistering, call it here. */
 	kfree(cxt->pstore.buf);
 	cxt->pstore.bufsize = 0;
 
+	persistent_ram_free(cxt->mprz);
+	persistent_ram_free(cxt->fprz);
+	persistent_ram_free(cxt->cprz);
+	ramoops_free_przs(cxt);
+
 	return 0;
-#endif
-	return -EBUSY;
 }
 
 static struct platform_driver ramoops_driver = {
 	.probe		= ramoops_probe,
-	.remove		= __exit_p(ramoops_remove),
+	.remove		= ramoops_remove,
 	.driver		= {
 		.name	= "ramoops",
 	},

include/linux/pstore.h

@@ -75,20 +75,8 @@ struct pstore_info {
 
 #define	PSTORE_FLAGS_FRAGILE	1
 
-#ifdef CONFIG_PSTORE
 extern int pstore_register(struct pstore_info *);
+extern void pstore_unregister(struct pstore_info *);
 extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason);
-#else
-static inline int
-pstore_register(struct pstore_info *psi)
-{
-	return -ENODEV;
-}
-static inline bool
-pstore_cannot_block_path(enum kmsg_dump_reason reason)
-{
-	return false;
-}
-#endif
 
 #endif /*_LINUX_PSTORE_H*/

kernel/printk/printk.c

@@ -517,6 +517,7 @@ int check_syslog_permissions(int type, int source)
 ok:
 	return security_syslog(type);
 }
+EXPORT_SYMBOL_GPL(check_syslog_permissions);
 
 static void append_char(char **pp, char *e, char c)
 {