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authorJakub Kicinski <kuba@kernel.org>2023-07-20 19:13:23 +0300
committerJakub Kicinski <kuba@kernel.org>2023-07-22 04:51:37 +0300
commit32ad45b76990ece9c5dd1fe7aae6e688c3baa647 (patch)
tree6d6f7665615bbbf6df95da8ea1d471380e25ccd5 /Documentation/networking
parent57f1f9dd3abea322173ea75a15887ccf14bbbe51 (diff)
downloadlinux-32ad45b76990ece9c5dd1fe7aae6e688c3baa647.tar.xz
docs: net: clarify the NAPI rules around XDP Tx
page pool and XDP should not be accessed from IRQ context which may happen if drivers try to clean up XDP TX with NAPI budget of 0. Link: https://lore.kernel.org/r/20230720161323.2025379-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/napi.rst13
1 files changed, 7 insertions, 6 deletions
diff --git a/Documentation/networking/napi.rst b/Documentation/networking/napi.rst
index a7a047742e93..7bf7b95c4f7a 100644
--- a/Documentation/networking/napi.rst
+++ b/Documentation/networking/napi.rst
@@ -65,15 +65,16 @@ argument - drivers can process completions for any number of Tx
packets but should only process up to ``budget`` number of
Rx packets. Rx processing is usually much more expensive.
-In other words, it is recommended to ignore the budget argument when
-performing TX buffer reclamation to ensure that the reclamation is not
-arbitrarily bounded; however, it is required to honor the budget argument
-for RX processing.
+In other words for Rx processing the ``budget`` argument limits how many
+packets driver can process in a single poll. Rx specific APIs like page
+pool or XDP cannot be used at all when ``budget`` is 0.
+skb Tx processing should happen regardless of the ``budget``, but if
+the argument is 0 driver cannot call any XDP (or page pool) APIs.
.. warning::
- The ``budget`` argument may be 0 if core tries to only process Tx completions
- and no Rx packets.
+ The ``budget`` argument may be 0 if core tries to only process
+ skb Tx completions and no Rx or XDP packets.
The poll method returns the amount of work done. If the driver still
has outstanding work to do (e.g. ``budget`` was exhausted)