* [PATCH net-next] xdp: document xdp_do_flush() before napi_complete_done()
@ 2023-01-17 9:43 Magnus Karlsson
2023-01-17 10:33 ` Toke Høiland-Jørgensen
2023-01-18 14:40 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Magnus Karlsson @ 2023-01-17 9:43 UTC (permalink / raw)
To: magnus.karlsson, bjorn, ast, daniel, netdev, jonathan.lemon,
maciej.fijalkowski, kuba, toke, pabeni, davem, brouer
Cc: bpf
From: Magnus Karlsson <magnus.karlsson@intel.com>
Document in the XDP_REDIRECT manual section that drivers must call
xdp_do_flush() before napi_complete_done(). The two reasons behind
this can be found following the links below.
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com
Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/
---
net/core/filter.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index ab811293ae5d..7a2b67893afd 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4128,9 +4128,13 @@ static const struct bpf_func_proto bpf_xdp_adjust_meta_proto = {
* bpf_redirect_info to actually enqueue the frame into a map type-specific
* bulk queue structure.
*
- * 3. Before exiting its NAPI poll loop, the driver will call xdp_do_flush(),
- * which will flush all the different bulk queues, thus completing the
- * redirect.
+ * 3. Before exiting its NAPI poll loop, the driver will call
+ * xdp_do_flush(), which will flush all the different bulk queues,
+ * thus completing the redirect. Note that xdp_do_flush() must be
+ * called before napi_complete_done() in the driver, as the
+ * XDP_REDIRECT logic relies on being inside a single NAPI instance
+ * through to the xdp_do_flush() call for RCU protection of all
+ * in-kernel data structures.
*/
/*
* Pointers to the map entries will be kept around for this whole sequence of
base-commit: 501543b4fff0ff70bde28a829eb8835081ccef2f
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] xdp: document xdp_do_flush() before napi_complete_done()
2023-01-17 9:43 [PATCH net-next] xdp: document xdp_do_flush() before napi_complete_done() Magnus Karlsson
@ 2023-01-17 10:33 ` Toke Høiland-Jørgensen
2023-01-18 14:40 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Toke Høiland-Jørgensen @ 2023-01-17 10:33 UTC (permalink / raw)
To: Magnus Karlsson, magnus.karlsson, bjorn, ast, daniel, netdev,
jonathan.lemon, maciej.fijalkowski, kuba, pabeni, davem, brouer
Cc: bpf
Magnus Karlsson <magnus.karlsson@gmail.com> writes:
> From: Magnus Karlsson <magnus.karlsson@intel.com>
>
> Document in the XDP_REDIRECT manual section that drivers must call
> xdp_do_flush() before napi_complete_done(). The two reasons behind
> this can be found following the links below.
>
> Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
> Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com
> Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/
Thanks for fixing this!
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] xdp: document xdp_do_flush() before napi_complete_done()
2023-01-17 9:43 [PATCH net-next] xdp: document xdp_do_flush() before napi_complete_done() Magnus Karlsson
2023-01-17 10:33 ` Toke Høiland-Jørgensen
@ 2023-01-18 14:40 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2023-01-18 14:40 UTC (permalink / raw)
To: Magnus Karlsson
Cc: magnus.karlsson, bjorn, ast, daniel, netdev, jonathan.lemon,
maciej.fijalkowski, kuba, toke, pabeni, davem, brouer, bpf
Hello:
This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:
On Tue, 17 Jan 2023 10:43:05 +0100 you wrote:
> From: Magnus Karlsson <magnus.karlsson@intel.com>
>
> Document in the XDP_REDIRECT manual section that drivers must call
> xdp_do_flush() before napi_complete_done(). The two reasons behind
> this can be found following the links below.
>
> Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
> Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com
> Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/
>
> [...]
Here is the summary with links:
- [net-next] xdp: document xdp_do_flush() before napi_complete_done()
https://git.kernel.org/netdev/net-next/c/68e5b6aa2795
You are awesome, thank you!
--
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-01-17 9:43 [PATCH net-next] xdp: document xdp_do_flush() before napi_complete_done() Magnus Karlsson
2023-01-17 10:33 ` Toke Høiland-Jørgensen
2023-01-18 14:40 ` patchwork-bot+netdevbpf
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