Commits
Will Deacon committed c139aa60c10
arm64: barriers: fix smp_load_acquire to work with const arguments
A newly introduced function in include/net/sock.h passes a const
argument to smp_load_acquire:
static inline int sk_state_load(const struct sock *sk)
{
return smp_load_acquire(&sk->sk_state);
}
This cause an allmodconfig build failure, since our underlying
load-acquire implementation does not handle const types correctly:
include/net/sock.h: In function 'sk_state_load':
./arch/arm64/include/asm/barrier.h:71:3: error: read-only variable '___p1' used as 'asm' output
asm volatile ("ldarb %w0, %1" \
This patch fixes the problem by reusing the trick in READ_ONCE that
loads via a non-const member of an anonymous union. This has the
advantage of allowing us to use smp_load_acquire on packed structures
(e.g. arch_spinlock_t) as well as primitive types.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Daney <david.daney@cavium.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: David Daney <david.daney@cavium.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>