efi/x86: drop task_lock() from efi_switch_mm()

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efi_switch_mm() is a wrapper around switch_mm() which saves current's
->active_mm, sets the requests mm as ->active_mm and invokes
switch_mm().
I don't think that task_lock() is required during that procedure. It
protects ->mm which isn't changed here.

It needs to be mentioned that during the whole procedure (switch to
EFI's mm and back) the preemption needs to be disabled. A context switch
at this point would reset the cr3 value based on current->mm. Also, this
function may not be invoked at the same time on a different CPU because
it would overwrite the efi_scratch.prev_mm information.

Remove task_lock() and also update the comment to reflect it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

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Sebastian Andrzej Siewior 2018-07-24 21:28:55 +02:00 • committed by Ard Biesheuvel

parent 3425d934fc

commit 4eda11175f

1 changed files with 4 additions and 6 deletions

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arch/x86/platform/efi/efi_64.c

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