efivars: Allow disabling use as a pstore backend

commit ed9dc8ce7a1c8115dba9483a9b51df8b63a2e0ef upstream.

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>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index efba163..59cc870 100644 (file)
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -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

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 81346ae..450f630 100644 (file)
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -659,8 +659,6 @@ static struct kobj_type efivar_ktype = {
        .default_attrs = def_attrs,
 };
 
-static struct pstore_info efi_pstore_info;
-
 static inline void
 efivar_unregister(struct efivar_entry *var)
 {
@@ -697,7 +695,7 @@ static int efi_status_to_err(efi_status_t status)
        return err;
 }
 
-#ifdef CONFIG_PSTORE
+#ifdef CONFIG_EFI_VARS_PSTORE
 
 static int efi_pstore_open(struct pstore_info *psi)
 {
@@ -847,36 +845,6 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id,
 
        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,
-                              struct timespec *timespec,
-                              char **buf, struct pstore_info *psi)
-{
-       return -1;
-}
-
-static int efi_pstore_write(enum pstore_type_id type, u64 *id,
-               unsigned int part, size_t size, struct pstore_info *psi)
-{
-       return 0;
-}
-
-static int efi_pstore_erase(enum pstore_type_id type, u64 id,
-                           struct pstore_info *psi)
-{
-       return 0;
-}
-#endif
 
 static struct pstore_info efi_pstore_info = {
        .owner          = THIS_MODULE,
@@ -888,6 +856,24 @@ 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)
@@ -1271,15 +1257,7 @@ 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);
 
 out:
        kfree(variable_name);