From: Mina Almasry Date: Thu, 7 Nov 2024 21:03:31 +0000 (+0000) Subject: net: clarify SO_DEVMEM_DONTNEED behavior in documentation X-Git-Tag: v6.12~15^2~17 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=102d1404c385611c574498b1e0d1f3762e253359;p=thirdparty%2Fkernel%2Fstable.git 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 Link: https://patch.msgid.link/20241107210331.3044434-2-almasrymina@google.com Signed-off-by: Jakub Kicinski --- 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 ========================