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Date: Mon, 15 Oct 2012 14:38:52 +0300
From: dragos.tatulea@...el.com
To: cbouatmailru@...il.com, linux-kernel@...r.kernel.org
Cc: adrian.hunter@...el.com, octavian.purdila@...el.com
Subject: [PATCH 3/8] pstore: add support for external writers
From: Adrian Hunter <adrian.hunter@...el.com>
Other modules that may wish to write to persistent storage
are supported by adding a notifier and write function.
The notifier has 3 events: PSTORE_BEGIN, PSTORE_DUMP and
PSTORE_END. External writers use the PSTORE_DUMP event
whereas the PSTORE_BEGIN and PSTORE_END can be used by
platform code to ensure the back end is powered up.
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
--
fs/pstore/platform.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/pstore.h | 43 +++++++++++++++++++----
2 files changed, 124 insertions(+), 7 deletions(-)
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 9d65723..63ff377 100644
-- a/fs/pstore/platform.c
++ b/fs/pstore/platform.c
@@ -34,6 +34,7 @@
#include <linux/jiffies.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/notifier.h>
#include "internal.h"
@@ -74,6 +75,20 @@ void pstore_set_kmsg_bytes(int bytes)
kmsg_bytes = bytes;
}
static ATOMIC_NOTIFIER_HEAD(pstore_notifiers);
int pstore_notifier_register(struct notifier_block *n)
{
return atomic_notifier_chain_register(&pstore_notifiers, n);
}
EXPORT_SYMBOL_GPL(pstore_notifier_register);
int pstore_notifier_unregister(struct notifier_block *n)
{
return atomic_notifier_chain_unregister(&pstore_notifiers, n);
}
EXPORT_SYMBOL_GPL(pstore_notifier_unregister);
/* Tag each group of saved records with a sequence number */
static int oopscount;
@@ -97,6 +112,26 @@ static const char *get_reason_str(enum kmsg_dump_reason reason)
}
}
static int pstore_ext_flush(void)
{
int ret;
if (!psinfo->ext_len)
return 0;
ret = psinfo->write(psinfo->ext_type, psinfo->ext_reason,
&psinfo->ext_id, psinfo->ext_part++,
psinfo->ext_len, psinfo);
if (ret == 0 && psinfo->ext_reason == KMSG_DUMP_OOPS &&
pstore_is_mounted())
pstore_new_entry = 1;
psinfo->ext_len = 0;
return ret;
}
/*
* callback from kmsg_dump. (s2,l2) has the most recently
* written bytes, older bytes are in (s1,l1). Save as much
@@ -122,6 +157,15 @@ static void pstore_dump(struct kmsg_dumper *dumper,
} else
spin_lock_irqsave(&psinfo->buf_lock, flags);
oopscount++;
psinfo->ext_id = 0;
psinfo->ext_len = 0;
psinfo->ext_part = 0;
psinfo->ext_type = PSTORE_TYPE_UNKNOWN;
psinfo->ext_reason = reason;
atomic_notifier_call_chain(&pstore_notifiers, PSTORE_BEGIN, psinfo);
while (total < kmsg_bytes) {
char *dst;
unsigned long size;
@@ -148,6 +192,13 @@ static void pstore_dump(struct kmsg_dumper *dumper,
total += hsize + len;
part++;
}
atomic_notifier_call_chain(&pstore_notifiers, PSTORE_DUMP, psinfo);
pstore_ext_flush();
atomic_notifier_call_chain(&pstore_notifiers, PSTORE_END, psinfo);
if (in_nmi()) {
if (is_locked)
spin_unlock(&psinfo->buf_lock);
@@ -368,5 +419,42 @@ static void pstore_timefunc(unsigned long dummy)
mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
}
/* pstore_write must only be called from PSTORE_DUMP notifier callbacks */
int pstore_write(enum pstore_type_id type, const char *buf, size_t size)
{
size_t len;
int err = 0, err2;
if (!psinfo)
return -ENODEV;
/*
* No locking is needed because pstore_write is called only from
* PSTORE_DUMP notifier callbacks.
*/
if (type != psinfo->ext_type) {
err = pstore_ext_flush();
psinfo->ext_type = type;
psinfo->ext_part = 1;
}
while (size) {
len = min(size, psinfo->bufsize - psinfo->ext_len);
memcpy(psinfo->buf + psinfo->ext_len, buf, len);
psinfo->ext_len += len;
buf += len;
size -= len;
if (psinfo->ext_len == psinfo->bufsize) {
err2 = pstore_ext_flush();
if (err2 && !err)
err = err2;
}
}
return err;
}
EXPORT_SYMBOL_GPL(pstore_write);
module_param(backend, charp, 0444);
MODULE_PARM_DESC(backend, "Pstore backend to use");
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 55ab23f..1bf7f4b 100644
-- a/include/linux/pstore.h
++ b/include/linux/pstore.h
@@ -40,17 +40,27 @@ enum pstore_type_id {
struct module;
/* Notifier events */
#define PSTORE_BEGIN 1
#define PSTORE_DUMP 2
#define PSTORE_END 3
#define PSTORE_NO_HEADINGS BIT(0)
#define PSTORE_MAX_KMSG_BYTES BIT(1)
struct pstore_info {
struct module *owner;
char *name;
unsigned int flags;
spinlock_t buf_lock; /* serialize access to 'buf' */
char *buf;
size_t bufsize;
struct mutex read_mutex; /* serialize open/read/close */
struct module *owner;
char *name;
unsigned int flags;
spinlock_t buf_lock; /* serialize access to 'buf' */
char *buf;
size_t bufsize;
struct mutex read_mutex; /* serialize open/read/close */
u64 ext_id;
size_t ext_len;
unsigned int ext_part;
enum pstore_type_id ext_type;
enum kmsg_dump_reason ext_reason;
int (*open)(struct pstore_info *psi);
int (*close)(struct pstore_info *psi);
ssize_t (*read)(u64 *id, enum pstore_type_id *type,
@@ -70,12 +80,31 @@ struct pstore_info {
#ifdef CONFIG_PSTORE
extern int pstore_register(struct pstore_info *);
extern int pstore_notifier_register(struct notifier_block *n);
extern int pstore_notifier_unregister(struct notifier_block *n);
/* pstore_write must only be called from PSTORE_DUMP notifier callbacks */
extern int pstore_write(enum pstore_type_id type, const char *buf, size_t size);
#else
static inline int
pstore_register(struct pstore_info *psi)
{
return -ENODEV;
}
static inline int
pstore_notifier_register(struct notifier_block *n)
{
return 0;
}
static inline int
pstore_notifier_unregister(struct notifier_block *n)
{
return 0;
}
static inline int
pstore_write(enum pstore_type_id type, const char *buf, size_t size)
{
return 0;
}
#endif
#endif /*_LINUX_PSTORE_H*/
-
1.7.9.5
--
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