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.
Even on a single-CPU system, I presume that the interrupt handler cannot
be pre-empted by a user-space call such as snd_pcm_status(). Is that
correct?
Alan.
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