Commit 102d1404 authored by Mina Almasry's avatar Mina Almasry Committed by Jakub Kicinski
Browse files

net: clarify SO_DEVMEM_DONTNEED behavior in documentation 



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

Signed-off-by: default avatarMina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20241107210331.3044434-2-almasrymina@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent f2685c00

Documentation/networking/devmem.rst

+9 −0
Original line number Diff line number Diff line
@@ -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

========================