Hi Viktor, On Fri, Jul 16, 2021 at 01:36:52AM +0300, Viktor Prutyanov wrote: > Hi Sean, > > On Thu, 15 Jul 2021 22:40:01 +0100 > Sean Young <sean@xxxxxxxx> wrote: > > > On Thu, Jul 15, 2021 at 12:27:06AM +0300, Viktor Prutyanov wrote: > > + meson_irtx_fill_buf(ir, tx_buf, buf, len); > > > + dev_dbg(ir->dev, "TX buffer filled, length = %u\n", len); > > > + > > > + spin_lock_irqsave(&ir->lock, flags); > > > + meson_irtx_update_buf(ir, tx_buf, len, 0); > > > + reinit_completion(&ir->completion); > > > + meson_irtx_send_buffer(ir); > > > + spin_unlock_irqrestore(&ir->lock, flags); > > > + > > > + ret = wait_for_completion_interruptible(&ir->completion); > > > + dev_dbg(ir->dev, "TX %s\n", ret ? "interrupted" : > > > "completed"); > > > > Here two things can happen. One is, the process received a signal > > (e.g. ^C). The other is that the hardware didn't issue any interrupts > > due some problem somewhere. In the latter case, we only escape this > > wait_for_completion_interruptable() when the user gets fed up and > > presses ^C or something like that. > > > > > + > > > + spin_lock_irqsave(&ir->lock, flags); > > > + kfree(ir->buf); > > > + meson_irtx_update_buf(ir, NULL, 0, 0); > > > + spin_unlock_irqrestore(&ir->lock, flags); > > > > Now it is possible that the buffer gets cleared before that IR was > > sent, if the signal was received early enough. This means not all the > > Tx was completed. > > > > > + > > > + return len; > > > > Yet, we always return success. > > > > In case no interrupts were generated we should return an error in a > > timely manner, so the wait_for_completion() needs the timeout. You > > can use the fact that the IR is never longer IR_MAX_DURATION (half a > > second currently). Not sure what the returned error should be, maybe > > -ETIMEDOUT? > > As for me, ETIMEDOUT is OK. > > > > The problem with the interruptable wait is that a process can receive > > a signal at any time, and now when this happens your IR gets > > truncated. I don't think this is what you want. > > Should I replace wait_for_completion_interruptible by > wait_for_completion_timeout in order to wait in uninterruptible way? Yes, the process can receive a signal if the terminal is resized (SIGWINCH) or if the process is backgrounded and then foregrounded with ^Z and fg (SIGCONT). If this happens during tx then the tx might be incomplete. Thanks, Sean
