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s390: use WRITE_ONCE when re-allocating async stack 

The code does:

S390_lowcore.async_stack = new + STACK_INIT_OFFSET;

But the compiler is free to first assign one value and
add the other value later. If a IRQ would be coming in
between these two operations, it would run with an invalid
stack. Prevent this by using WRITE_ONCE.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Sven Schnelle 2021-02-10 13:39:19 +01:00 committed by Vasily Gorbik
parent b0d31159a4
commit 64985c3a22
1 changed files with 1 additions and 1 deletions
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2
arch/s390/kernel/setup.c
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@ -346,7 +346,7 @@ static int __init async_stack_realloc(void)
new = stack_alloc();
if (!new)
panic("Couldn't allocate async stack");
S390_lowcore.async_stack = new + STACK_INIT_OFFSET;
WRITE_ONCE(S390_lowcore.async_stack, new + STACK_INIT_OFFSET);
free_pages(old, THREAD_SIZE_ORDER);
return 0;
}