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Subject[PATCH 5/9] arm64: correctly check for ktrheads
Date
Since commit:

6eb6c80187c55b7f ("arm64: kernel thread don't need to save fpsimd context.")

... we skip saving the fpsimd state for kernel threads in
arch_dup_task_struct(). We determine whether current is a kthread by
looking at current->mm.

In general, a non-NULL current->mm doesn't imply that current is a
kthread, as kthreads can install an mm via use_mm(), and so it's
preferable to use is_kthread() to determine whether a thread is a
kthread.

For consistency, let's use is_kthread() here.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/process.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 288012687c29..82b0a7a257cd 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -335,7 +335,7 @@ void arch_release_task_struct(struct task_struct *tsk)
*/
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
- if (current->mm)
+ if (!is_kthread(current))
fpsimd_preserve_current_state();
*dst = *src;

--
2.11.0
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