efi_pstore: Add a sequence counter to a variable name

[Issue]

Currently, a variable name, which identifies 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.

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

In case of a write callback executed in pstore_console_write(), "0" is added to
an argument of the write callback because it just logs all kernel messages and
doesn't need to care about multiple events.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mike Waychison <mikew@google.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index f6e93362d259..1788909d9a99 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;
 };