efi: Don't use spinlocks for efi vars
All efivars operations are protected by a spinlock which prevents
interruptions and preemption. This is too restricted, we just need a
lock preventing concurrency.
The idea is to use a semaphore of count 1 and to have two ways of
locking, depending on the context:
- In interrupt context, we call down_trylock(), if it fails we return
an error
- In normal context, we call down_interruptible()
We don't use a mutex here because the mutex_trylock() function must not
be called from interrupt context, whereas the down_trylock() can.
Signed-off-by: Sylvain Chouleur <sylvain.chouleur@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sylvain Chouleur <sylvain.chouleur@gmail.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c
index 116b244..3e626fd 100644
--- a/drivers/firmware/efi/efivars.c
+++ b/drivers/firmware/efi/efivars.c
@@ -510,7 +510,8 @@
vendor = del_var->VendorGuid;
}
- efivar_entry_iter_begin();
+ if (efivar_entry_iter_begin())
+ return -EINTR;
entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
if (!entry)
err = -EINVAL;
@@ -575,7 +576,10 @@
return ret;
kobject_uevent(&new_var->kobj, KOBJ_ADD);
- efivar_entry_add(new_var, &efivar_sysfs_list);
+ if (efivar_entry_add(new_var, &efivar_sysfs_list)) {
+ efivar_unregister(new_var);
+ return -EINTR;
+ }
return 0;
}
@@ -690,7 +694,10 @@
static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
{
- efivar_entry_remove(entry);
+ int err = efivar_entry_remove(entry);
+
+ if (err)
+ return err;
efivar_unregister(entry);
return 0;
}
@@ -698,7 +705,14 @@
static void efivars_sysfs_exit(void)
{
/* Remove all entries and destroy */
- __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list, NULL, NULL);
+ int err;
+
+ err = __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list,
+ NULL, NULL);
+ if (err) {
+ pr_err("efivars: Failed to destroy sysfs entries\n");
+ return;
+ }
if (efivars_new_var)
sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);