[Problem]
When efi_pstore holds just one log and it doesn't overwrite an exisiting entry,
we lose a critical message if kernel panics while system is rebooting.
[Solution]
With this patch, efi_pstore can hold multiple logs with a new kernel parameter, efi_pstore_log_num.
We can simply avoid losing a critical message in case mutiple events happen.
[Patch Description]
- Introduce a new kernel parameter specifying the number of logs efi_pstore holds.
- Pass ctime to an argument of erase callback.
- Current variable name consists of type, id and ctime. So, when handling mutiple logs,
pstore should pass ctime to erase callback to avoid erasing invisible entries via /dev/pstore.
Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx>
---
Documentation/kernel-parameters.txt | 6 ++++++
drivers/acpi/apei/erst.c | 4 ++--
drivers/firmware/efivars.c | 33 +++++++++++++++++++++++++--------
fs/pstore/inode.c | 2 +-
fs/pstore/ram.c | 2 +-
include/linux/pstore.h | 2 +-
6 files changed, 36 insertions(+), 13 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a92c5eb..9d38561 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -786,6 +786,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
edd= [EDD]
Format: {"off" | "on" | "skip[mbr]"}
+ efivars.efi_pstore_log_num=
+ Set the maximum number of logs efi_pstore saves into
+ NVRAM. n >= 1 limits the number of logs. n <= 0 is
+ invalid.
+ default: 1
+
eisa_irq_edge= [PARISC,HW]
See header of drivers/parisc/eisa.c.
diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
index e4d9d24..0bd6ae4 100644
--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -938,7 +938,7 @@ static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
u64 *id, unsigned int part,
size_t size, struct pstore_info *psi);
static int erst_clearer(enum pstore_type_id type, u64 id,
- struct pstore_info *psi);
+ struct timespec time, struct pstore_info *psi);
static struct pstore_info erst_info = {
.owner = THIS_MODULE,
@@ -1102,7 +1102,7 @@ static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
}
static int erst_clearer(enum pstore_type_id type, u64 id,
- struct pstore_info *psi)
+ struct timespec time, struct pstore_info *psi)
{
return erst_clear(id);
}
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 75a7c82..55188d7 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -628,6 +628,27 @@ efivar_unregister(struct efivar_entry *var)
#ifdef CONFIG_PSTORE
+static unsigned long efi_pstore_log_num = 1;
+static int param_set_efi_pstore_log_num(const char *val,
+ struct kernel_param *kp)
+{
+ int ret;
+ unsigned long l;
+
+ ret = kstrtoul(val, 0, &l);
+ if (ret || l == 0)
+ return -EINVAL;
+
+ ret = param_set_ulong(val, kp);
+ if (ret)
+ return -EINVAL;
+
+ return 0;
+}
+
+module_param_call(efi_pstore_log_num, param_set_efi_pstore_log_num,
+ param_get_ulong, &efi_pstore_log_num, S_IRUGO | S_IWUSR);
+
static int efi_pstore_open(struct pstore_info *psi)
{
struct efivars *efivars = psi->data;
@@ -731,7 +752,7 @@ static int efi_pstore_write(enum pstore_type_id type,
current_log_num = get_current_log_num(efi_name, efivars);
- if (current_log_num >= 1) {
+ if (current_log_num >= efi_pstore_log_num) {
spin_unlock(&efivars->lock);
*id = part;
return -EEXIST;
@@ -756,7 +777,7 @@ static int efi_pstore_write(enum pstore_type_id type,
};
static int efi_pstore_erase(enum pstore_type_id type, u64 id,
- struct pstore_info *psi)
+ struct timespec time, struct pstore_info *psi)
{
char stub_name[DUMP_NAME_LEN];
efi_char16_t efi_name[DUMP_NAME_LEN];
@@ -765,7 +786,7 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id,
struct efivar_entry *entry, *found = NULL;
int i;
- sprintf(stub_name, "dump-type%u-%llu-", type, id);
+ sprintf(stub_name, "dump-type%u-%llu-%lu", type, id, time.tv_sec);
spin_lock(&efivars->lock);
@@ -783,10 +804,6 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id,
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;
/* found */
found = entry;
@@ -832,7 +849,7 @@ static int efi_pstore_write(enum pstore_type_id type,
}
static int efi_pstore_erase(enum pstore_type_id type, u64 id,
- struct pstore_info *psi)
+ struct timespec time, struct pstore_info *psi)
{
return 0;
}
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 11a2aa2..9acd703 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -75,7 +75,7 @@ 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, p->psi);
+ p->psi->erase(p->type, p->id, dentry->d_inode->i_ctime, p->psi);
return simple_unlink(dir, dentry);
}
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 453030f..06357c9 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -178,7 +178,7 @@ static int ramoops_pstore_write(enum pstore_type_id type,
}
static int ramoops_pstore_erase(enum pstore_type_id type, u64 id,
- struct pstore_info *psi)
+ 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 e1461e1..92cb90e 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -48,7 +48,7 @@ struct pstore_info {
enum kmsg_dump_reason reason, u64 *id,
unsigned int part, size_t size, struct pstore_info *psi);
int (*erase)(enum pstore_type_id type, u64 id,
- struct pstore_info *psi);
+ struct timespec time, struct pstore_info *psi);
void *data;
};
-- 1.7.1
--
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