From: Ard Biesheuvel <[email protected]>

This introduces a new runtime wrapper for the QueryVariableInfo() UEFI
Runtime Service, which gives up immediately rather than spins on failure
to grab the efi_runtime spinlock.

This is required in the non-blocking path of the efi-pstore code.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Matt Fleming <[email protected]>
---
 drivers/firmware/efi/runtime-wrappers.c | 22 ++++++++++++++++++++++
 include/linux/efi.h                     |  1 +
 2 files changed, 23 insertions(+)

diff --git a/drivers/firmware/efi/runtime-wrappers.c 
b/drivers/firmware/efi/runtime-wrappers.c
index 228bbf910461..e9f2867f0d91 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -230,6 +230,27 @@ static efi_status_t virt_efi_query_variable_info(u32 attr,
        return status;
 }
 
+static efi_status_t
+virt_efi_query_variable_info_nonblocking(u32 attr,
+                                        u64 *storage_space,
+                                        u64 *remaining_space,
+                                        u64 *max_variable_size)
+{
+       unsigned long flags;
+       efi_status_t status;
+
+       if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
+               return EFI_UNSUPPORTED;
+
+       if (!spin_trylock_irqsave(&efi_runtime_lock, flags))
+               return EFI_NOT_READY;
+
+       status = efi_call_virt(query_variable_info, attr, storage_space,
+                              remaining_space, max_variable_size);
+       spin_unlock_irqrestore(&efi_runtime_lock, flags);
+       return status;
+}
+
 static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
 {
        unsigned long flags;
@@ -300,6 +321,7 @@ void efi_native_runtime_setup(void)
        efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
        efi.reset_system = virt_efi_reset_system;
        efi.query_variable_info = virt_efi_query_variable_info;
+       efi.query_variable_info_nonblocking = 
virt_efi_query_variable_info_nonblocking;
        efi.update_capsule = virt_efi_update_capsule;
        efi.query_capsule_caps = virt_efi_query_capsule_caps;
 }
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8706e0aabedc..ad1e177ba48e 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -849,6 +849,7 @@ extern struct efi {
        efi_set_variable_t *set_variable;
        efi_set_variable_t *set_variable_nonblocking;
        efi_query_variable_info_t *query_variable_info;
+       efi_query_variable_info_t *query_variable_info_nonblocking;
        efi_update_capsule_t *update_capsule;
        efi_query_capsule_caps_t *query_capsule_caps;
        efi_get_next_high_mono_count_t *get_next_high_mono_count;
-- 
2.6.2

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