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efi: Don't use spinlocks for efi vars

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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>
This commit is contained in:
Sylvain Chouleur
2016-07-15 21:36:30 +02:00
committed by Matt Fleming
parent 217b27d467
commit 21b3ddd39f
6 changed files with 139 additions and 76 deletions
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22
drivers/firmware/efi/efivars.c
View File

@@ -510,7 +510,8 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
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 @@ efivar_create_sysfs_entry(struct efivar_entry *new_var)
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 efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
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 int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
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);