FelipeMdeO opened a new pull request, #3763:
URL: https://github.com/apache/nuttx-apps/pull/3763
## Summary
`uorb_listener`'s `%pB` debug printing (`orb_info()` -> `lib_bsprintf()`)
performs real floating-point-to-string conversion synchronously, inside the
listener's own task -- it is not a lightweight pointer dump. With
`CONFIG_LIBC_PRINT_EXTENSION` off, `%pB` just prints a raw pointer and the
default `CONFIG_UORB_STACKSIZE` (`DEFAULT_TASK_STACKSIZE`, 2048 on most
configs) is plenty. With it on, decoding a topic's float fields through this
path silently overflows a 2048-byte stack.
Confirmed on real hardware (ESP32-S3, two subscribed float topics pushing
every ~10-20ms): `uorb_listener` hangs completely after printing only a partial
topic name -- no panic, no stack dump, nothing -- because
`CONFIG_SCHED_STACKGUARD`/`CONFIG_STACK_COLORATION` aren't on by default
either, so there's no guard to catch the overflow before it corrupts adjacent
memory.
Raising the default only when `CONFIG_LIBC_PRINT_EXTENSION` is set (not
unconditionally, and not keyed off `CONFIG_DEBUG_UORB` specifically, since
anything else that selects the same libc extension hits the same path) keeps
the common case -- raw pointer output, small stack -- exactly as before, and
only pays for the extra stack when the feature that needs it is actually
enabled.
## Impact
`CONFIG_UORB_STACKSIZE` default changes from `DEFAULT_TASK_STACKSIZE` to
4096 **only** for configs with `CONFIG_LIBC_PRINT_EXTENSION=y`. No change for
any other config. Users who already have an explicit `CONFIG_UORB_STACKSIZE`
recorded in their `.config` are unaffected by this default either way (see note
below).
.. note::
This default only applies when `CONFIG_UORB_STACKSIZE` has never been
explicitly recorded in `.config`. Like any Kconfig int default, flipping
`CONFIG_LIBC_PRINT_EXTENSION` on in an existing `.config` that already has an
explicit `CONFIG_UORB_STACKSIZE` value won't retroactively raise it -- the
value has to be re-picked (e.g. via a fresh `olddefconfig` after removing the
stale line, or manually via menuconfig).
## Testing
Host: Ubuntu 24.04.4 LTS. `xtensa-esp-elf-gcc` (crosstool-NG
esp-14.2.0_20241119) 14.2.0. `checkpatch.sh` (style + `-m` commit message)
clean.
On hardware -- Seeed XIAO ESP32-S3, `CONFIG_LIBC_PRINT_EXTENSION=y`,
`uorb_listener` subscribed to two float-based topics streaming continuously:
- `CONFIG_UORB_STACKSIZE=2048` (the old default): reproduces the hang every
time, output cuts off mid topic-name print, console never responds again.
- `CONFIG_UORB_STACKSIZE=4096` (this PR's new default): runs cleanly,
verified repeatedly across multiple fresh boots for 10+ seconds continuous,
fully decoded output, e.g.:
```
sensor_gyro(now:20410000):timestamp:20410000,x:0.008399,y:-0.041386,z:0.017409,temperature:31.000000
sensor_accel(now:20390000):timestamp:20390000,x:-6.385280,y:0.358925,z:-7.318485,temperature:31.000000
```
- `CONFIG_UORB_STACKSIZE=8192`: also works, confirming 4096 isn't a
coincidental pass and there's headroom either way.
- End-to-end with the actual Kconfig default mechanism (not a manual
override): starting from a `.config` where `CONFIG_UORB_STACKSIZE` was never
set, enabling `CONFIG_LIBC_PRINT_EXTENSION` and running `make olddefconfig`
resolves `CONFIG_UORB_STACKSIZE` to 4096 automatically; the resulting build was
flashed and validated live on the bench with the same clean, continuous decoded
output as above.
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