Panic in jdevelop/gpio

[Vlad Korniev]

Hello,

Sorry for opening issue here, but it's related to jdevelop/gpio fork where I can't open one.

Sometimes gpio lib is panicking due to null in watchEventCallbacks while using rf522:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x5e815528]

goroutine 56 [running]:
github.com/jdevelop/gpio.setupEpoll.func1()
        /go/pkg/mod/github.com/jdevelop/gpio@v0.0.0-20180116031910-0e2cc992019a/gpio_linux.go:81 +0x13c
created by github.com/jdevelop/gpio.setupEpoll
        /go/pkg/mod/github.com/jdevelop/gpio@v0.0.0-20180116031910-0e2cc992019a/gpio_linux.go:67 +0x5c

I would assume that's because Wait was called meanwhile and IrqPin.EndWatch triggers deletion from the map. Maybe it makes sense to mutex it?

[Vlad Korniev]

Yep, just got another one with more context

fatal error: concurrent map read and map write

goroutine 45 [running]:
runtime.throw(0x5e99decd, 0x21)
        /usr/local/go/src/runtime/panic.go:608 +0x64 fp=0x185f6a0 sp=0x185f68c pc=0x5e8c8220
runtime.mapaccess2_fast32(0x5e9f7f10, 0x157a200, 0xb, 0x10, 0xffffffff)
        /usr/local/go/src/runtime/map_fast32.go:61 +0x1b4 fp=0x185f6b0 sp=0x185f6a0 pc=0x5e8ab310
github.com/jdevelop/gpio.setupEpoll.func1()
        /go/pkg/mod/github.com/jdevelop/gpio@v0.0.0-20180116031910-0e2cc992019a/gpio_linux.go:80 +0x128 fp=0x185f7ec sp=0x185f6b0 pc=0x5e98e514
runtime.goexit()
        /usr/local/go/src/runtime/asm_arm.s:867 +0x4 fp=0x185f7ec sp=0x185f7ec pc=0x23fbc0
created by github.com/jdevelop/gpio.setupEpoll
        /go/pkg/mod/github.com/jdevelop/gpio@v0.0.0-20180116031910-0e2cc992019a/gpio_linux.go:67 +0x5c

[Eugene]

I would rather suggest to give it a try for periph

It does work fine with Raspberry Pi Zero / Zero W and has more robust support for IRQ events.