C fallthrough: Which version of the Linux kernel?

[david-a-wheeler]

The current text says, "The C17 standard does not provide a mechanism to mark intentional fallthroughs....". It then notes the Linux kernel. Is it version 5.10 or 6.4 that started using this?

[06kellyjac]

Commits I've found for fallthrough

• torvalds/linux@f7a858b v6.4-rc1
• torvalds/linux@1926140 (v4.11-rc1)
  • https://sourcegraph.com/search?q=context:global+repo:%5Egithub%5C.com/torvalds/linux%24%401926140+content:fallthrough%3B&patternType=regexp&sm=0
• torvalds/linux@b5bf173 (v4.11-rc1)
  • https://sourcegraph.com/search?q=context:global+repo:%5Egithub%5C.com/torvalds/linux%24%40b5bf173+content:fallthrough%3B&patternType=regexp&sm=0

Could be missing some bits. I've not found a reference around 5.10

---

https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10
if you want to ctrl+f through for fallthrough

docs:

not here yet
https://www.kernel.org/doc/html/v5.1/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

starts to appear
https://www.kernel.org/doc/html/v5.3/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

https://www.kernel.org/doc/html/v5.10/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

https://www.kernel.org/doc/html/v6.4/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

https://www.kernel.org/doc/html/v6.9/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

[thomasnyman]

I am also not sure where the reference to 5.10 originates from. I was responsible for adding the last sentence of the section, referring to 6.4 after I also found torvalds/linux@1926140 to be the first commit with fallthrough in the form the guide originally referred to.

Addressing this inconsistency in #494 that also removes the redundant note below the example.