efi_pstore: Add a format check for an existing variable name at erasing time

[Issue]

a format of variable name has been updated to type, id, count and ctime
to support holding multiple logs.

Format of current variable name
  dump-type0-1-2-12345678

  type:0
  id:1
  count:2
  ctime:12345678

On the other hand, if an old variable name before being updated
remains, users can't erase it via /dev/pstore.

Format of old variable name
  dump-type0-1-12345678

  type:0
  id:1
  ctime:12345678

[Solution]

This patch add a format check for the old variable name in a erase callback to make it erasable.

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

1 files changed, 18 insertions, 2 deletions

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index bf7a6f994a3c..6e51c1e81f14 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -773,6 +773,8 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 {
         char name[DUMP_NAME_LEN];
         efi_char16_t efi_name[DUMP_NAME_LEN];
+        char name_old[DUMP_NAME_LEN];
+        efi_char16_t efi_name_old[DUMP_NAME_LEN];
         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
         struct efivars *efivars = psi->data;
         struct efivar_entry *entry, *found = NULL;
@@ -796,8 +798,22 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
                 if (efi_guidcmp(entry->var.VendorGuid, vendor))
                         continue;
                 if (utf16_strncmp(entry->var.VariableName, efi_name,
-                                  utf16_strlen(efi_name)))
-                        continue;
+                                  utf16_strlen(efi_name))) {
+                        /*
+                         * Check if an old format,
+                         * which doesn't support holding
+                         * multiple logs, remains.
+                         */
+                        sprintf(name_old, "dump-type%u-%u-%lu", type,
+                                (unsigned int)id, time.tv_sec);
+
+                        for (i = 0; i < DUMP_NAME_LEN; i++)
+                                efi_name_old[i] = name_old[i];
+
+                        if (utf16_strncmp(entry->var.VariableName, efi_name_old,
+                                          utf16_strlen(efi_name_old)))
+                                continue;
+                }
 
                 /* found */
                 found = entry;