On Tue, May 19, 2020 at 04:58:37PM -0700, Andrew Morton wrote: > On Tue, 19 May 2020 22:19:08 +0200 Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > > + local_lock(swapvec_lock); > > It's quite peculiar that these operations appear to be pass-by-value. > All other locking operations are pass-by-reference - spin_lock(&lock), > not spin_lock(lock). This is what the eye expects to see and it's > simply more logical - calling code shouldn't have to "know" that the > locking operations are implemented as cpp macros. And we'd be in a > mess if someone tried to convert these to real C functions. The funny thing is that the documentation gets this right: +The mapping of local_lock to spinlock_t on PREEMPT_RT kernels has a few +implications. For example, on a non-PREEMPT_RT kernel the following code +sequence works as expected:: + + local_lock_irq(&local_lock); + raw_spin_lock(&lock); but apparently the implementation changed without the documentation matching.
