[PATCH v2 3/3] pstore: add pstore unregister

From: Geliang Tang
Date: Sun Oct 18 2015 - 06:53:14 EST

pstore doesn't support unregistering yet. It was marked as TODO.
This patch adds some code to fix it:
1) Add functions to unregister kmsg/console/ftrace/pmsg.
2) Add a function to free compression buffer.
3) Unmap the memory and free it.
4) Add a function to unregister pstore filesystem.

Signed-off-by: Geliang Tang <geliangtang@xxxxxxx>
---
Changes in v2:
- Add pstore filesystem unregister.
- update commit log.
---
fs/pstore/Kconfig | 2 +-
fs/pstore/Makefile | 6 +++---
fs/pstore/ftrace.c | 23 ++++++++++++++++++-----
fs/pstore/inode.c | 7 +++++++
fs/pstore/internal.h | 4 ++++
fs/pstore/platform.c | 35 +++++++++++++++++++++++++++++++++++
fs/pstore/pmsg.c | 7 +++++++
fs/pstore/ram.c | 17 +++++++----------
include/linux/pstore.h | 14 +-------------
kernel/printk/printk.c | 1 +
10 files changed, 84 insertions(+), 32 deletions(-)

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 916b8e2..360ae43 100644
--- a/fs/pstore/Kconfig
+++ b/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
diff --git a/fs/pstore/Makefile b/fs/pstore/Makefile
index e647d8e..b8803cc 100644
--- a/fs/pstore/Makefile
+++ b/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
diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c
index 76a4eeb..788600f 100644
--- a/fs/pstore/ftrace.c
+++ b/fs/pstore/ftrace.c
@@ -104,21 +104,22 @@ 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,
+ 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__);
@@ -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);
}
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 3adcc46..598b52a 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -479,5 +479,12 @@ 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@xxxxxxxxx>");
MODULE_LICENSE("GPL");
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index c36ba2c..96253c4 100644
--- a/fs/pstore/internal.h
+++ b/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;
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 1b11249..0aab920 100644
--- a/fs/pstore/platform.c
+++ b/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
@@ -358,6 +366,11 @@ 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)
{
@@ -395,8 +408,14 @@ 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,
@@ -467,12 +486,28 @@ 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
diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c
index 5a2f05a..7de20cd 100644
--- a/fs/pstore/pmsg.c
+++ b/fs/pstore/pmsg.c
@@ -114,3 +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);
+}
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 6c26c4d..68889a7 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -580,28 +580,25 @@ fail_out:

static int __exit 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",
},
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 8e7a25b..831479f 100644
--- a/include/linux/pstore.h
+++ b/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*/
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 8f0324e..b16f354 100644
--- a/kernel/printk/printk.c
+++ b/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)
{
--
2.5.0


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