[tip:efi/core] efi/x86: Use non-blocking SetVariable() for efi_delete_dummy_variable()

[tip-bot for Sai Praneeth]

Commit-ID:  5a58bc1b1edc18a9edff606ec99e6f6b723975f4
Gitweb:     https://git.kernel.org/tip/5a58bc1b1edc18a9edff606ec99e6f6b723975f4
Author:     Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx>
AuthorDate: Wed, 11 Jul 2018 11:40:34 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 16 Jul 2018 00:43:12 +0200

efi/x86: Use non-blocking SetVariable() for efi_delete_dummy_variable()

Presently, efi_delete_dummy_variable() uses set_variable() which might
block, which the scheduler is rightfully upset about when used from
the idle thread, producing this splat:

  "bad: scheduling from the idle thread!"

So, make efi_delete_dummy_variable() use set_variable_nonblocking(),
which, as the name suggests, doesn't block.

Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20180711094040.12506-3-ard.biesheuvel@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/platform/efi/quirks.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 36c1f8b9f7e0..6af39dc40325 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -105,12 +105,11 @@ early_param("efi_no_storage_paranoia", setup_storage_paranoia);
 */
 void efi_delete_dummy_variable(void)
 {
-	efi.set_variable((efi_char16_t *)efi_dummy_name,
-			 &EFI_DUMMY_GUID,
-			 EFI_VARIABLE_NON_VOLATILE |
-			 EFI_VARIABLE_BOOTSERVICE_ACCESS |
-			 EFI_VARIABLE_RUNTIME_ACCESS,
-			 0, NULL);
+	efi.set_variable_nonblocking((efi_char16_t *)efi_dummy_name,
+				     &EFI_DUMMY_GUID,
+				     EFI_VARIABLE_NON_VOLATILE |
+				     EFI_VARIABLE_BOOTSERVICE_ACCESS |
+				     EFI_VARIABLE_RUNTIME_ACCESS, 0, NULL);
 }
 
 /*