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Message-Id: <1350558367-31801-4-git-send-email-dragos.tatulea@intel.com>
Date: Thu, 18 Oct 2012 14:06:01 +0300
From: dragos.tatulea@...el.com
To: ccross@...roid.com, keescook@...omium.org, tony.luck@...el.com,
cbouatmailru@...il.com, linux-kernel@...r.kernel.org
Cc: adrian.hunter@...el.com, octavian.purdila@...el.com
Subject: [PATCH v3 3/9] 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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