[RFC][PATCH 2/2] efi_pstore: add a sequence counter to a variablename

[Seiji Aguchi]

[Problem]

Currently, a variable name, which distinguishes each entry, consists of type, id and ctime.
But if multiple events happens in a short time, a second/third event may fail to log because
efi_pstore can't distinguish each event with current variable name.

[Solution]

  A reasonable way to identify all events precisely is introducing a sequence counter to
  the variable name.

[Patch Description]

  The sequence counter has already supported in a pstore layer with "oopscount".
  So, this patch adds it to a variable name.
  Also, it is passed to read/erase callbacks of platform drivers in accordance with
  the modification of the variable name.

  <before applying this patch>
 a variable name of first event: dump-type0-1-12345678
 a variable name of second event: dump-type0-1-12345678

  type:0
  id:1
  ctime:12345678

 If multiple events happen in a short time, efi_pstore can't distinguish them because
 variable names are same among them.

  <after applying this patch>

 it can be distinguishable by adding a sequence counter as follows.

 a variable name of first event: dump-type0-1-1-12345678
 a variable name of Second event: dump-type0-1-2-12345678

  type:0
  id:1
  sequence counter: 1(first event), 2(second event)
  ctime:12345678

Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx>
---
 drivers/acpi/apei/erst.c   |   12 ++++++------
 drivers/firmware/efivars.c |   25 ++++++++++++++++---------
 fs/pstore/inode.c          |    8 +++++---
 fs/pstore/internal.h       |    2 +-
 fs/pstore/platform.c       |   11 ++++++-----
 fs/pstore/ram.c            |    7 +++----
 include/linux/pstore.h     |    8 +++++---
 7 files changed, 42 insertions(+), 31 deletions(-)

diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
index 0bd6ae4..6d894bf 100644
--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -931,13 +931,13 @@ static int erst_check_table(struct acpi_table_erst *erst_tab)
 
 static int erst_open_pstore(struct pstore_info *psi);
 static int erst_close_pstore(struct pstore_info *psi);
-static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
+static ssize_t erst_reader(u64 *id, enum pstore_type_id *type, int *count,
 			   struct timespec *time, char **buf,
 			   struct pstore_info *psi);
 static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
-		       u64 *id, unsigned int part,
+		       u64 *id, unsigned int part, int count,
 		       size_t size, struct pstore_info *psi);
-static int erst_clearer(enum pstore_type_id type, u64 id,
+static int erst_clearer(enum pstore_type_id type, u64 id, int count,
 			struct timespec time, struct pstore_info *psi);
 
 static struct pstore_info erst_info = {
@@ -987,7 +987,7 @@ static int erst_close_pstore(struct pstore_info *psi)
 	return 0;
 }
 
-static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
+static ssize_t erst_reader(u64 *id, enum pstore_type_id *type, int *count,
 			   struct timespec *time, char **buf,
 			   struct pstore_info *psi)
 {
@@ -1055,7 +1055,7 @@ out:
 }
 
 static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
-		       u64 *id, unsigned int part,
+		       u64 *id, unsigned int part, int count,
 		       size_t size, struct pstore_info *psi)
 {
 	struct cper_pstore_record *rcd = (struct cper_pstore_record *)
@@ -1101,7 +1101,7 @@ static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
 	return ret;
 }
 
-static int erst_clearer(enum pstore_type_id type, u64 id,
+static int erst_clearer(enum pstore_type_id type, u64 id, int count,
 			struct timespec time, struct pstore_info *psi)
 {
 	return erst_clear(id);
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 0eaaba3..511d6ee 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -658,13 +658,14 @@ static int efi_pstore_close(struct pstore_info *psi)
 }
 
 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
-			       struct timespec *timespec,
+			       int *count, struct timespec *timespec,
 			       char **buf, struct pstore_info *psi)
 {
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 	struct efivars *efivars = psi->data;
 	char name[DUMP_NAME_LEN];
 	int i;
+	int cnt;
 	unsigned int part, size;
 	unsigned long time;
 
@@ -674,8 +675,10 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 			for (i = 0; i < DUMP_NAME_LEN; i++) {
 				name[i] = efivars->walk_entry->var.VariableName[i];
 			}
-			if (sscanf(name, "dump-type%u-%u-%lu", type, &part, &time) == 3) {
+			if (sscanf(name, "dump-type%u-%u-%d-%lu",
+				   type, &part, &cnt, &time) == 4) {
 				*id = part;
+				*count = cnt;
 				timespec->tv_sec = time;
 				timespec->tv_nsec = 0;
 				get_var_data_locked(efivars, &efivars->walk_entry->var);
@@ -698,7 +701,8 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 
 static int efi_pstore_write(enum pstore_type_id type,
 		enum kmsg_dump_reason reason, u64 *id,
-		unsigned int part, size_t size, struct pstore_info *psi)
+		unsigned int part, int count, size_t size,
+		struct pstore_info *psi)
 {
 	char name[DUMP_NAME_LEN];
 	efi_char16_t efi_name[DUMP_NAME_LEN];
@@ -726,7 +730,8 @@ static int efi_pstore_write(enum pstore_type_id type,
 		return -ENOSPC;
 	}
 
-	sprintf(name, "dump-type%u-%u-%lu", type, part, get_seconds());
+	sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count,
+		get_seconds());
 
 	for (i = 0; i < DUMP_NAME_LEN; i++)
 		efi_name[i] = name[i];
@@ -746,7 +751,7 @@ static int efi_pstore_write(enum pstore_type_id type,
 	return ret;
 };
 
-static int efi_pstore_erase(enum pstore_type_id type, u64 id,
+static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 			    struct timespec time, struct pstore_info *psi)
 {
 	char name[DUMP_NAME_LEN];
@@ -756,7 +761,8 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id,
 	struct efivar_entry *entry, *found = NULL;
 	int i;
 
-	sprintf(name, "dump-type%u-%llu-%lu", type, id, time.tv_sec);
+	sprintf(name, "dump-type%u-%llu-%d-%lu", type, id, count,
+		time.tv_sec);
 
 	spin_lock(&efivars->lock);
 
@@ -806,7 +812,7 @@ static int efi_pstore_close(struct pstore_info *psi)
 	return 0;
 }
 
-static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
+static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type, int *count,
 			       struct timespec *timespec,
 			       char **buf, struct pstore_info *psi)
 {
@@ -815,12 +821,13 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 
 static int efi_pstore_write(enum pstore_type_id type,
 		enum kmsg_dump_reason reason, u64 *id,
-		unsigned int part, size_t size, struct pstore_info *psi)
+		unsigned int part, int count, size_t size,
+		struct pstore_info *psi)
 {
 	return 0;
 }
 
-static int efi_pstore_erase(enum pstore_type_id type, u64 id,
+static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 			    struct timespec time, struct pstore_info *psi)
 {
 	return 0;
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 4300af6..ed1d8c7 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -49,6 +49,7 @@ struct pstore_private {
 	struct pstore_info *psi;
 	enum pstore_type_id type;
 	u64	id;
+	int	count;
 	ssize_t	size;
 	char	data[];
 };
@@ -175,8 +176,8 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 	struct pstore_private *p = dentry->d_inode->i_private;
 
 	if (p->psi->erase)
-		p->psi->erase(p->type, p->id, dentry->d_inode->i_ctime,
-			      p->psi);
+		p->psi->erase(p->type, p->id, p->count,
+			      dentry->d_inode->i_ctime, p->psi);
 
 	return simple_unlink(dir, dentry);
 }
@@ -271,7 +272,7 @@ int pstore_is_mounted(void)
  * Load it up with "size" bytes of data from "buf".
  * Set the mtime & ctime to the date that this record was originally stored.
  */
-int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
+int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
 		  char *data, size_t size, struct timespec time,
 		  struct pstore_info *psi)
 {
@@ -307,6 +308,7 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
 		goto fail_alloc;
 	private->type = type;
 	private->id = id;
+	private->count = count;
 	private->psi = psi;
 
 	switch (type) {
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index 0d0d3b7..e170a66 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -44,7 +44,7 @@ extern struct pstore_info *psinfo;
 extern void	pstore_set_kmsg_bytes(int);
 extern void	pstore_get_records(int);
 extern int	pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
-			      char *data, size_t size,
+			      int count, char *data, size_t size,
 			      struct timespec time, struct pstore_info *psi);
 extern int	pstore_is_mounted(void);
 
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 29996e8..5a07c9e 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -136,7 +136,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 			break;
 
 		ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
-				    hsize + len, psinfo);
+				    oopscount, hsize + len, psinfo);
 		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 			pstore_new_entry = 1;
 
@@ -190,7 +190,7 @@ static void pstore_register_console(void) {}
 
 static int pstore_write_compat(enum pstore_type_id type,
 			       enum kmsg_dump_reason reason,
-			       u64 *id, unsigned int part,
+			       u64 *id, unsigned int part, int count,
 			       size_t size, struct pstore_info *psi)
 {
 	return psi->write_buf(type, reason, id, part, psinfo->buf, size, psi);
@@ -259,6 +259,7 @@ void pstore_get_records(int quiet)
 	char			*buf = NULL;
 	ssize_t			size;
 	u64			id;
+	int			count;
 	enum pstore_type_id	type;
 	struct timespec		time;
 	int			failed = 0, rc;
@@ -270,9 +271,9 @@ void pstore_get_records(int quiet)
 	if (psi->open && psi->open(psi))
 		goto out;
 
-	while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
-		rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
-				  time, psi);
+	while ((size = psi->read(&id, &type, &count, &time, &buf, psi)) > 0) {
+		rc = pstore_mkfile(type, psi->name, id, count, buf,
+				  (size_t)size, time, psi);
 		kfree(buf);
 		buf = NULL;
 		if (rc && (rc != -EEXIST || !quiet))
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 177b281..403a5fc 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -131,9 +131,8 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
 }
 
 static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
-				   struct timespec *time,
-				   char **buf,
-				   struct pstore_info *psi)
+				   int *count, struct timespec *time,
+				   char **buf, struct pstore_info *psi)
 {
 	ssize_t size;
 	struct ramoops_context *cxt = psi->data;
@@ -236,7 +235,7 @@ static int ramoops_pstore_write_buf(enum pstore_type_id type,
 	return 0;
 }
 
-static int ramoops_pstore_erase(enum pstore_type_id type, u64 id,
+static int ramoops_pstore_erase(enum pstore_type_id type, u64 id, int count,
 				timespec time, struct pstore_info *psi)
 {
 	struct ramoops_context *cxt = psi->data;
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 71f43e0..c768758 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -50,17 +50,19 @@ struct pstore_info {
 	int		(*open)(struct pstore_info *psi);
 	int		(*close)(struct pstore_info *psi);
 	ssize_t		(*read)(u64 *id, enum pstore_type_id *type,
-			struct timespec *time, char **buf,
+			int *count, struct timespec *time, char **buf,
 			struct pstore_info *psi);
 	int		(*write)(enum pstore_type_id type,
 			enum kmsg_dump_reason reason, u64 *id,
-			unsigned int part, size_t size, struct pstore_info *psi);
+			unsigned int part, int count, size_t size,
+			struct pstore_info *psi);
 	int		(*write_buf)(enum pstore_type_id type,
 			enum kmsg_dump_reason reason, u64 *id,
 			unsigned int part, const char *buf, size_t size,
 			struct pstore_info *psi);
 	int		(*erase)(enum pstore_type_id type, u64 id,
-			struct timespec time, struct pstore_info *psi);
+			int count, struct timespec time,
+			struct pstore_info *psi);
 	void		*data;
 };
 
-- 1.7.1
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