3a0fb4b9bf
uart_tcdrain() takes a caller-supplied timeout (e.g. 10s from the
TCDRN ioctl path), but the timeout was only applied to the final
TX-FIFO polling loop. The earlier xmit-buffer drain loop called
nxsem_wait(&dev->xmitsem) with no timeout, so any condition that
prevents the lower half from posting xmitsem (e.g. a stuck DMA
completion path, a wedged hardware-flow-control stall) would block
tcdrain() indefinitely, regardless of the timeout the caller asked
for. The pre-existing comment ("NOTE: There is no timeout on the
following loop. ... the caller should call tcflush() first") openly
acknowledged this hang.
Move the start timestamp before both phases and replace the bare
nxsem_wait() with nxsem_tickwait() using the remaining time, so the
total time spent in tcdrain() honors the caller's timeout regardless
of which phase stalls. When the remaining time is already exhausted,
short-circuit to -ETIMEDOUT without calling into the scheduler. The
existing exit path (drop critical section, skip the FIFO polling
loop, unlock the xmit mutex, leave the cancellation point) handles
the new -ETIMEDOUT propagation correctly without further changes.
Also fold the "Set up for the timeout" comment into the kludge
REVISIT comment, since the timestamp is no longer set up at that
point.
Signed-off-by: Lingao Meng <menglingao@xiaomi.com>
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|---|---|---|
| .github | ||
| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .codespell-ignore-lines | ||
| .codespellrc | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmessage | ||
| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.