From 102d1404c385611c574498b1e0d1f3762e253359 Mon Sep 17 00:00:00 2001 From: Mina Almasry <almasrymina@google.com> Date: Thu, 7 Nov 2024 21:03:31 +0000 Subject: [PATCH] net: clarify SO_DEVMEM_DONTNEED behavior in documentation 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> --- Documentation/networking/devmem.rst | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/networking/devmem.rst b/Documentation/networking/devmem.rst index a55bf21f671c3..d953636453314 100644 --- a/Documentation/networking/devmem.rst +++ b/Documentation/networking/devmem.rst @@ -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 ======================== -- GitLab