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net: clarify SO_DEVMEM_DONTNEED behavior in documentation

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Document new behavior when the number of frags passed is too big.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20241107210331.3044434-2-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Mina Almasry 2024-11-07 21:03:31 +00:00 committed by Jakub Kicinski
parent f2685c00c3
commit 102d1404c3
1 changed files with 9 additions and 0 deletions
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Documentation/networking/devmem.rst
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@ -225,6 +225,15 @@ The user must ensure the tokens are returned to the kernel in a timely manner.
Failure to do so will exhaust the limited dmabuf that is bound to the RX queue
and will lead to packet drops.
The user must pass no more than 128 tokens, with no more than 1024 total frags
among the token->token_count across all the tokens. If the user provides more
than 1024 frags, the kernel will free up to 1024 frags and return early.
The kernel returns the number of actual frags freed. The number of frags freed
can be less than the tokens provided by the user in case of:
(a) an internal kernel leak bug.
(b) the user passed more than 1024 frags.
Implementation & Caveats
========================