RPI4 gpioTerminate() Hangs

[wschopohl]

guymcswain asked me to create a new issue for this - before I was adding comments to issue #478

I'm using pigpio library on a raspberry 4 with a buildroot aarch64 custom image using BusyBox as init system.

Problem: I had problems with a simple test program, that would work fine when running, but would hang once I called gpioTerminate().

Inspection: When trying to pinpoint the error, I started with the pigpiod application. The pigpiod application would also hang when I sent it a SIGHUP or SIGTERM signal - although reading the source code it should terminate nicely also using the gpioTerminate() call.

After investigating a bit more with my limited gdb skills, it seems like the fifo interface is causing problems in my case. When I start pigpiod with the -f option, I can stop it with a SIGTERM signal.

Solution: That means in my program I can use this code to disable the fifo interface and everything works as expected:

gpioCfgInterfaces(PI_DISABLE_FIFO_IF); // call before gpioInitialise()

Calling gpioTerminate() will not hang anymore and I can stop my test program nicely.

Out Words: In my case this solution is sufficient, because I don't need a fifo interface. I opened this issue to make you guys aware of this and to offer a solution to users that might end up with a similar problem.