Messages in this thread | | | Date | Mon, 6 Jul 2020 21:40:12 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 00/22] add support for Clang LTO |
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On Mon, Jul 06, 2020 at 11:39:33AM -0700, Paul E. McKenney wrote: > On Mon, Jul 06, 2020 at 08:29:26PM +0200, Peter Zijlstra wrote: > > On Mon, Jul 06, 2020 at 09:26:33AM -0700, Paul E. McKenney wrote:
> > If they do not consider their Linux OS running correctly :-) > > Many of them really do not care at all. In fact, some would consider > Linux failing to run as an added bonus.
This I think is why we have compiler people in the thread that care a lot more.
> > > Nevertheless, yes, control dependencies also need attention. > > > > Today I added one more \o/ > > Just make sure you continually check to make sure that compilers > don't break it, along with the others you have added. ;-)
There's:
kernel/locking/mcs_spinlock.h: smp_cond_load_acquire(l, VAL); \ kernel/sched/core.c: smp_cond_load_acquire(&p->on_cpu, !VAL); kernel/smp.c: smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
arch/x86/kernel/alternative.c: atomic_cond_read_acquire(&desc.refs, !VAL); kernel/locking/qrwlock.c: atomic_cond_read_acquire(&lock->cnts, !(VAL & _QW_LOCKED)); kernel/locking/qrwlock.c: atomic_cond_read_acquire(&lock->cnts, !(VAL & _QW_LOCKED)); kernel/locking/qrwlock.c: atomic_cond_read_acquire(&lock->cnts, VAL == _QW_WAITING); kernel/locking/qspinlock.c: atomic_cond_read_acquire(&lock->val, !(VAL & _Q_LOCKED_MASK)); kernel/locking/qspinlock.c: val = atomic_cond_read_acquire(&lock->val, !(VAL & _Q_LOCKED_PENDING_MASK));
include/linux/refcount.h: smp_acquire__after_ctrl_dep(); ipc/mqueue.c: smp_acquire__after_ctrl_dep(); ipc/msg.c: smp_acquire__after_ctrl_dep(); ipc/sem.c: smp_acquire__after_ctrl_dep(); kernel/locking/rwsem.c: smp_acquire__after_ctrl_dep(); kernel/sched/core.c: smp_acquire__after_ctrl_dep();
kernel/events/ring_buffer.c:__perf_output_begin()
And I'm fairly sure I'm forgetting some... One could argue there's too many of them to check already.
Both GCC and CLANG had better think about it.
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