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efi: Add nonblocking option to efi_query_variable_store()

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The function efi_query_variable_store() may be invoked by
efivar_entry_set_nonblocking(), which itself takes care to only
call a non-blocking version of the SetVariable() runtime
wrapper. However, efi_query_variable_store() may call the
SetVariable() wrapper directly, as well as the wrapper for
QueryVariableInfo(), both of which could deadlock in the same
way we are trying to prevent by calling
efivar_entry_set_nonblocking() in the first place.

So instead, modify efi_query_variable_store() to use the
non-blocking variants of QueryVariableInfo() (and give up rather
than free up space if the available space is below
EFI_MIN_RESERVE) if invoked with the 'nonblocking' argument set
to true.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1454364428-494-5-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ard Biesheuvel
2016-02-01 22:06:58 +00:00
committed by Ingo Molnar
parent d3cac1f83c
commit ca0e30dcaa
3 changed files with 55 additions and 6 deletions
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12
include/linux/efi.h
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@@ -525,7 +525,9 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
unsigned long count,
u64 *max_size,
int *reset_type);
typedef efi_status_t efi_query_variable_store_t(u32 attributes, unsigned long size);
typedef efi_status_t efi_query_variable_store_t(u32 attributes,
unsigned long size,
bool nonblocking);
void efi_native_runtime_setup(void);
@@ -881,13 +883,17 @@ extern void efi_enter_virtual_mode (void); /* switch EFI to virtual mode, if pos
#ifdef CONFIG_X86
extern void efi_late_init(void);
extern void efi_free_boot_services(void);
extern efi_status_t efi_query_variable_store(u32 attributes, unsigned long size);
extern efi_status_t efi_query_variable_store(u32 attributes,
unsigned long size,
bool nonblocking);
extern void efi_find_mirror(void);
#else
static inline void efi_late_init(void) {}
static inline void efi_free_boot_services(void) {}
static inline efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
static inline efi_status_t efi_query_variable_store(u32 attributes,
unsigned long size,
bool nonblocking)
{
return EFI_SUCCESS;
}