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, 14 insertions, 9 deletions

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 3803621c0d4..7ad3aae6e08 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];
@@ -725,7 +729,7 @@ static int efi_pstore_write(enum pstore_type_id type,
                 return -ENOSPC;
         }
 
-        sprintf(name, "dump-type%u-%u-%lu", type, part,
+        sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count,
                 get_seconds());
 
         for (i = 0; i < DUMP_NAME_LEN; i++)
@@ -746,7 +750,7 @@ 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 +760,7 @@ 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-%u-%lu", type, (unsigned int)id,
+        sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count,
                 time.tv_sec);
 
         spin_lock(&efivars->lock);
@@ -807,7 +811,7 @@ 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)
 {
@@ -816,12 +820,13 @@ 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;