init_process_flags.is_lock_free check fails on mipsel

[kapouer]

Version

v18.11.0

Platform

Linux 4.19.0-21-octeon #1 SMP Debian 4.19.249-2 (2022-06-30) mips64el (mips64)

Subsystem

node

What steps will reproduce the bug?

Build nodejs with mipsel target. On debian.

How often does it reproduce? Is there a required condition?

Something about the slowness of the host arch maybe ?

What is the expected behavior?

Same thing used to work with nodejs 18.10.0.

What do you see instead?

./out/Release/node --completion-bash > ./debian/nodejs.bash-completion
./out/Release/node[12071]: ../src/node.cc:603:void node::PlatformInit(ProcessFlags::Flags): Assertion `init_process_flags.is_lock_free()' failed.
Aborted

full build log

Additional information

As usual, I know this isn't a supported architecture.
However it might be a hidden bug actually affecting other architectures, only on high load.

Build machine info.

[bnoordhuis]

The comment for that assert explains it:

// init_process_flags is accessed in ResetStdio(),
// which can be called from signal handlers.

If it's not lock-free, it's protected by a mutex, and mutexes aren't safe to use inside a signal handler (can deadlock.)

Try changing it from an atomic uint64_t to a uint32_t. There are only 12 flags so that should fit and uint32_t likely is lock-free on mipsel. Pull request welcome.

[kapouer]

Changing it to std:atomic<uint32_t> works, but you meant I should change it to just uint32_t right ?

[bnoordhuis]

Sorry, no: std:atomic<uint32_t> - it needs to stay atomic.