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efivars: Allow disabling use as a pstore backend
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Add a new option, CONFIG_EFI_VARS_PSTORE, which can be set to N to
avoid using efivars as a backend to pstore, as some users may want to
compile out the code completely.

Set the default to Y to maintain backwards compatability, since this
feature has always been enabled until now.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
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Seth Forshee authored and Matt Fleming committed Mar 21, 2013
1 parent f6161aa commit ed9dc8c
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Showing 2 changed files with 29 additions and 44 deletions.
9 changes: 9 additions & 0 deletions drivers/firmware/Kconfig
Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,15 @@ config EFI_VARS
Subsequent efibootmgr releases may be found at:
<http://linux.dell.com/efibootmgr>

config EFI_VARS_PSTORE
bool "Register efivars backend for pstore"
depends on EFI_VARS && PSTORE
default y
help
Say Y here to enable use efivars as a backend to pstore. This
will allow writing console messages, crash dumps, or anything
else supported by pstore to EFI variables.

config EFI_PCDP
bool "Console device selection via EFI PCDP or HCDP table"
depends on ACPI && EFI && IA64
Expand Down
64 changes: 20 additions & 44 deletions drivers/firmware/efivars.c
Original file line number Diff line number Diff line change
Expand Up @@ -1309,9 +1309,7 @@ static const struct inode_operations efivarfs_dir_inode_operations = {
.create = efivarfs_create,
};

static struct pstore_info efi_pstore_info;

#ifdef CONFIG_PSTORE
#ifdef CONFIG_EFI_VARS_PSTORE

static int efi_pstore_open(struct pstore_info *psi)
{
Expand Down Expand Up @@ -1514,38 +1512,6 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,

return 0;
}
#else
static int efi_pstore_open(struct pstore_info *psi)
{
return 0;
}

static int efi_pstore_close(struct pstore_info *psi)
{
return 0;
}

static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type, int *count,
struct timespec *timespec,
char **buf, struct pstore_info *psi)
{
return -1;
}

static int efi_pstore_write(enum pstore_type_id type,
enum kmsg_dump_reason reason, u64 *id,
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, int count,
struct timespec time, struct pstore_info *psi)
{
return 0;
}
#endif

static struct pstore_info efi_pstore_info = {
.owner = THIS_MODULE,
Expand All @@ -1557,6 +1523,24 @@ static struct pstore_info efi_pstore_info = {
.erase = efi_pstore_erase,
};

static void efivar_pstore_register(struct efivars *efivars)
{
efivars->efi_pstore_info = efi_pstore_info;
efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
if (efivars->efi_pstore_info.buf) {
efivars->efi_pstore_info.bufsize = 1024;
efivars->efi_pstore_info.data = efivars;
spin_lock_init(&efivars->efi_pstore_info.buf_lock);
pstore_register(&efivars->efi_pstore_info);
}
}
#else
static void efivar_pstore_register(struct efivars *efivars)
{
return;
}
#endif

static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t pos, size_t count)
Expand Down Expand Up @@ -2025,15 +2009,7 @@ int register_efivars(struct efivars *efivars,
if (error)
unregister_efivars(efivars);

efivars->efi_pstore_info = efi_pstore_info;

efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
if (efivars->efi_pstore_info.buf) {
efivars->efi_pstore_info.bufsize = 1024;
efivars->efi_pstore_info.data = efivars;
spin_lock_init(&efivars->efi_pstore_info.buf_lock);
pstore_register(&efivars->efi_pstore_info);
}
efivar_pstore_register(efivars);

register_filesystem(&efivarfs_type);

Expand Down

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