Alan Young wrote: > On 07/11/16 14:15, Clemens Ladisch wrote: >> Alan Young wrote: >>> It is possible that the DMA interrupt handler could call >>> snd_pcm_update_hw_ptr0() while it is part way through a call >>> from snd_pcm_status(), or vice versa? >> >> The *lock_irq* functions disable interrupts on the current CPU. > > But only on the current CPU? So that would imply that multiple threads > could execute snd_pcm_update_hw_ptr0() simultaneously on multi-CPU > systems. That's what the lock is for. > I presume that the interrupt handler cannot be pre-empted by a user- > space call such as snd_pcm_status(). During execution of an interrupt handler, interrupts also are disabled. Regards, Clemens _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
