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Date: Thu, 19 Jul 2012 21:12:57 +0000
From: Seiji Aguchi <seiji.aguchi@....com>
To: "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
"mikew@...gle.com" <mikew@...gle.com>,
"dzickus@...hat.com" <dzickus@...hat.com>,
"Matthew Garrett (mjg@...hat.com)" <mjg@...hat.com>
CC: "dle-develop@...ts.sourceforge.net"
<dle-develop@...ts.sourceforge.net>,
Satoru Moriya <satoru.moriya@....com>
Subject: [RFC][PATCH v2 1/3] Avoid overwriting existing entry
[Problem]
Currently, efi_pstore driver simply overwrites existing panic messages in NVRAM.
So, in the following scenario, we will lose 1st panic messages.
1. kernel panics.
2. efi_pstore is kicked and write panic messages to NVRAM.
3. system reboots.
4. kernel panics again before a user checks the 1st panic messages in NVRAM.
[Solution]
This patch remove a logic erasing existing entries from write callback to
avoid losing an existing critical message.
[Patch Description]
- Remove a logic erasing existing entries from write callback
- Add the logic above to erase callback.
Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
---
drivers/firmware/efivars.c | 92 +++++++++++++++++++++++++++++++++-----------
1 files changed, 69 insertions(+), 23 deletions(-)
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 47408e8..75a7c82 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -685,6 +685,30 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
return 0;
}
+static unsigned long get_current_log_num(efi_char16_t *efi_name,
+ struct efivars *efivars)
+{
+ efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+ struct efivar_entry *entry;
+ unsigned long current_log_num = 0;
+
+ list_for_each_entry(entry, &efivars->list, list) {
+ get_var_data_locked(efivars, &entry->var);
+
+ if (efi_guidcmp(entry->var.VendorGuid, vendor))
+ continue;
+ if (utf16_strncmp(entry->var.VariableName, efi_name,
+ utf16_strlen(efi_name)))
+ continue;
+ /* Needs to be a prefix */
+ if (entry->var.VariableName[utf16_strlen(efi_name)] == 0)
+ continue;
+ current_log_num++;
+ }
+
+ return current_log_num;
+}
+
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)
@@ -694,8 +718,8 @@ static int efi_pstore_write(enum pstore_type_id type,
efi_char16_t efi_name[DUMP_NAME_LEN];
efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
struct efivars *efivars = psi->data;
- struct efivar_entry *entry, *found = NULL;
int i, ret = 0;
+ unsigned long current_log_num;
sprintf(stub_name, "dump-type%u-%u-", type, part);
sprintf(name, "%s%lu", stub_name, get_seconds());
@@ -705,6 +729,48 @@ static int efi_pstore_write(enum pstore_type_id type,
for (i = 0; i < DUMP_NAME_LEN; i++)
efi_name[i] = stub_name[i];
+ current_log_num = get_current_log_num(efi_name, efivars);
+
+ if (current_log_num >= 1) {
+ spin_unlock(&efivars->lock);
+ *id = part;
+ return -EEXIST;
+ }
+
+ for (i = 0; i < DUMP_NAME_LEN; i++)
+ efi_name[i] = name[i];
+
+ efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES,
+ size, psi->buf);
+
+ spin_unlock(&efivars->lock);
+
+ if (size)
+ ret = efivar_create_sysfs_entry(efivars,
+ utf16_strsize(efi_name,
+ DUMP_NAME_LEN * 2),
+ efi_name, &vendor);
+
+ *id = part;
+ return ret;
+};
+
+static int efi_pstore_erase(enum pstore_type_id type, u64 id,
+ struct pstore_info *psi)
+{
+ char stub_name[DUMP_NAME_LEN];
+ efi_char16_t efi_name[DUMP_NAME_LEN];
+ efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+ struct efivars *efivars = psi->data;
+ struct efivar_entry *entry, *found = NULL;
+ int i;
+
+ sprintf(stub_name, "dump-type%u-%llu-", type, id);
+
+ spin_lock(&efivars->lock);
+
+ for (i = 0; i < DUMP_NAME_LEN; i++)
+ efi_name[i] = stub_name[i];
/*
* Clean up any entries with the same name
*/
@@ -718,7 +784,8 @@ static int efi_pstore_write(enum pstore_type_id type,
utf16_strlen(efi_name)))
continue;
/* Needs to be a prefix */
- if (entry->var.VariableName[utf16_strlen(efi_name)] == 0)
+ if (entry->var.VariableName[utf16_strlen(efi_name)]
+ == 0)
continue;
/* found */
@@ -732,32 +799,11 @@ static int efi_pstore_write(enum pstore_type_id type,
if (found)
list_del(&found->list);
- for (i = 0; i < DUMP_NAME_LEN; i++)
- efi_name[i] = name[i];
-
- efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES,
- size, psi->buf);
-
spin_unlock(&efivars->lock);
if (found)
efivar_unregister(found);
- if (size)
- ret = efivar_create_sysfs_entry(efivars,
- utf16_strsize(efi_name,
- DUMP_NAME_LEN * 2),
- efi_name, &vendor);
-
- *id = part;
- return ret;
-};
-
-static int efi_pstore_erase(enum pstore_type_id type, u64 id,
- struct pstore_info *psi)
-{
- efi_pstore_write(type, 0, &id, (unsigned int)id, 0, psi);
-
return 0;
}
#else
-- 1.7.1
--
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