riscv: add a return value to riscv_swint

[hujun260]

Summary

add a return value to riscv_swint indicating whether a context switch is required

This commit fixes the regression from #13561

Impact

Testing

ostest

[nuttxpr]

[Experimental Bot, please feedback here]

Yes, the PR appears to meet the NuttX requirements.

Here's a breakdown:

• Summary: Clearly explains the "why" (fixing a regression), "what" (adding a return value to a specific function), and "how" (referencing the original PR that caused the regression). It also links to the original PR.
• Impact: While lacking details, it implies minimal impact since it's a fix for a regression. More specifics about the impact (e.g., on compatibility) would strengthen this section.
• Testing: Provides basic testing information (platform: ostest). Including testing logs before and after the change would significantly improve the thoroughness of this section.

Recommendations for Improvement:

• Impact: Expand on the potential impact areas. Even if the impact is minimal, explicitly stating this helps reviewers. For example:
  • Compatibility: "This change only affects internal scheduling logic and has no backward or forward compatibility impact."
  • Hardware/Build: "No changes to hardware or build process are required."
• Testing:
  • Include actual "before" and "after" testing logs to demonstrate the fix.
  • If possible, test on more than one platform or configuration to increase confidence.

Overall: The PR provides a good starting point. Adding the recommended details will ensure a smoother review process and increase the likelihood of a quick merge.

[lupyuen]

OSTest seems to hang at vfork() for rv-virt:knsh? https://gist.github.com/lupyuen/8daee1123a52e222fb601287a00af149

$ git clone https://github.com/hujun260/nuttx --branch apache_10 nuttx
$ tools/configure.sh rv-virt:knsh
...
$ qemu-system-riscv32 -semihosting -M virt,aclint=on -cpu rv32 -kernel nuttx -bios opensbi-1.5-rv-bin/share/opensbi/ilp32/generic/firmware/fw_dynamic.bin -nographic
QEMU emulator version 9.0.2
OpenSBI v1.5
...
nsh> ostest
user_main: vfork() test
[Hangs here]

Update: rv-virt:knsh64 also hangs at vfork(): https://gist.github.com/lupyuen/ce2e2cb328073d25743adbd4bc4a9b87

[hujun260]

OSTest seems to hang at vfork() for rv-virt:knsh? https://gist.github.com/lupyuen/8daee1123a52e222fb601287a00af149

$ git clone https://github.com/hujun260/nuttx --branch apache_10 nuttx
$ tools/configure.sh rv-virt:knsh
...
$ qemu-system-riscv32 -semihosting -M virt,aclint=on -cpu rv32 -kernel nuttx -bios opensbi-1.5-rv-bin/share/opensbi/ilp32/generic/firmware/fw_dynamic.bin -nographic
QEMU emulator version 9.0.2
OpenSBI v1.5
...
nsh> ostest
user_main: vfork() test
[Hangs here]

Update: rv-virt:knsh64 also hangs at vfork(): https://gist.github.com/lupyuen/ce2e2cb328073d25743adbd4bc4a9b87

i fixed this issue

[lupyuen]

OSTest is now OK on rv-virt:knsh, rv-virt:knsh64 and milkv_duos:nsh thanks!