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path: root/drivers/firmware/efi/vars.c
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Diffstat (limited to 'drivers/firmware/efi/vars.c')
-rw-r--r--drivers/firmware/efi/vars.c61
1 files changed, 54 insertions, 7 deletions
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index 5abe943e3404..70a0fb10517f 100644
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -321,11 +321,11 @@ static unsigned long var_name_strnsize(efi_char16_t *variable_name,
* Print a warning when duplicate EFI variables are encountered and
* disable the sysfs workqueue since the firmware is buggy.
*/
-static void dup_variable_bug(efi_char16_t *s16, efi_guid_t *vendor_guid,
+static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
unsigned long len16)
{
size_t i, len8 = len16 / sizeof(efi_char16_t);
- char *s8;
+ char *str8;
/*
* Disable the workqueue since the algorithm it uses for
@@ -334,16 +334,16 @@ static void dup_variable_bug(efi_char16_t *s16, efi_guid_t *vendor_guid,
*/
efivar_wq_enabled = false;
- s8 = kzalloc(len8, GFP_KERNEL);
- if (!s8)
+ str8 = kzalloc(len8, GFP_KERNEL);
+ if (!str8)
return;
for (i = 0; i < len8; i++)
- s8[i] = s16[i];
+ str8[i] = str16[i];
printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
- s8, vendor_guid);
- kfree(s8);
+ str8, vendor_guid);
+ kfree(str8);
}
/**
@@ -595,6 +595,39 @@ int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
}
EXPORT_SYMBOL_GPL(efivar_entry_set);
+/*
+ * efivar_entry_set_nonblocking - call set_variable_nonblocking()
+ *
+ * This function is guaranteed to not block and is suitable for calling
+ * from crash/panic handlers.
+ *
+ * Crucially, this function will not block if it cannot acquire
+ * __efivars->lock. Instead, it returns -EBUSY.
+ */
+static int
+efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
+ u32 attributes, unsigned long size, void *data)
+{
+ const struct efivar_operations *ops = __efivars->ops;
+ unsigned long flags;
+ efi_status_t status;
+
+ if (!spin_trylock_irqsave(&__efivars->lock, flags))
+ return -EBUSY;
+
+ status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
+ if (status != EFI_SUCCESS) {
+ spin_unlock_irqrestore(&__efivars->lock, flags);
+ return -ENOSPC;
+ }
+
+ status = ops->set_variable_nonblocking(name, &vendor, attributes,
+ size, data);
+
+ spin_unlock_irqrestore(&__efivars->lock, flags);
+ return efi_status_to_err(status);
+}
+
/**
* efivar_entry_set_safe - call set_variable() if enough space in firmware
* @name: buffer containing the variable name
@@ -622,6 +655,20 @@ int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes,
if (!ops->query_variable_store)
return -ENOSYS;
+ /*
+ * If the EFI variable backend provides a non-blocking
+ * ->set_variable() operation and we're in a context where we
+ * cannot block, then we need to use it to avoid live-locks,
+ * since the implication is that the regular ->set_variable()
+ * will block.
+ *
+ * If no ->set_variable_nonblocking() is provided then
+ * ->set_variable() is assumed to be non-blocking.
+ */
+ if (!block && ops->set_variable_nonblocking)
+ return efivar_entry_set_nonblocking(name, vendor, attributes,
+ size, data);
+
if (!block) {
if (!spin_trylock_irqsave(&__efivars->lock, flags))
return -EBUSY;