[PATCH 5.15 v2] gve: Fixes for napi_poll when budget is 0

[PATCH 5.15 v2] gve: Fixes for napi_poll when budget is 0

[Ziwei Xiao]

Netpoll will explicitly pass the polling call with a budget of 0 to
indicate it's clearing the Tx path only. For the gve_rx_poll and
gve_xdp_poll, they were mistakenly taking the 0 budget as the indication
to do all the work. Add check to avoid the rx path and xdp path being
called when budget is 0. And also avoid napi_complete_done being called
when budget is 0 for netpoll.

The original fix was merged here:
https://lore.kernel.org/r/20231114004144.2022268-1-ziweixiao@google.com
Resend it since the original one was not cleanly applied to 5.15 kernel.

commit 278a370c1766 ("gve: Fixes for napi_poll when budget is 0")

Fixes: f5cedc84a30d ("gve: Add transmit and receive support")
Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Praveen Kaligineedi <pkaligineedi@google.com>
---
 Changes in v2:
 * Add the original git commit id
---
 drivers/net/ethernet/google/gve/gve_main.c | 7 +++++++
 drivers/net/ethernet/google/gve/gve_rx.c   | 4 ----
 drivers/net/ethernet/google/gve/gve_tx.c   | 4 ----
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index bf8a4a7c43f7..c3f1959533a8 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -198,6 +198,10 @@ static int gve_napi_poll(struct napi_struct *napi, int budget)
 
 	if (block->tx)
 		reschedule |= gve_tx_poll(block, budget);
+
+	if (!budget)
+		return 0;
+
 	if (block->rx)
 		reschedule |= gve_rx_poll(block, budget);
 
@@ -246,6 +250,9 @@ static int gve_napi_poll_dqo(struct napi_struct *napi, int budget)
 	if (block->tx)
 		reschedule |= gve_tx_poll_dqo(block, /*do_clean=*/true);
 
+	if (!budget)
+		return 0;
+
 	if (block->rx) {
 		work_done = gve_rx_poll_dqo(block, budget);
 		reschedule |= work_done == budget;
diff --git a/drivers/net/ethernet/google/gve/gve_rx.c b/drivers/net/ethernet/google/gve/gve_rx.c
index 94941d4e4744..368e0e770178 100644
--- a/drivers/net/ethernet/google/gve/gve_rx.c
+++ b/drivers/net/ethernet/google/gve/gve_rx.c
@@ -599,10 +599,6 @@ bool gve_rx_poll(struct gve_notify_block *block, int budget)
 
 	feat = block->napi.dev->features;
 
-	/* If budget is 0, do all the work */
-	if (budget == 0)
-		budget = INT_MAX;
-
 	if (budget > 0)
 		repoll |= gve_clean_rx_done(rx, budget, feat);
 	else
diff --git a/drivers/net/ethernet/google/gve/gve_tx.c b/drivers/net/ethernet/google/gve/gve_tx.c
index 665ac795a1ad..d56b8356f1f3 100644
--- a/drivers/net/ethernet/google/gve/gve_tx.c
+++ b/drivers/net/ethernet/google/gve/gve_tx.c
@@ -691,10 +691,6 @@ bool gve_tx_poll(struct gve_notify_block *block, int budget)
 	u32 nic_done;
 	u32 to_do;
 
-	/* If budget is 0, do all the work */
-	if (budget == 0)
-		budget = INT_MAX;
-
 	/* Find out how much work there is to be done */
 	tx->last_nic_done = gve_tx_load_event_counter(priv, tx);
 	nic_done = be32_to_cpu(tx->last_nic_done);
-- 
2.47.0.338.g60cca15819-goog

Re: [PATCH 5.15 v2] gve: Fixes for napi_poll when budget is 0

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

Found matching upstream commit: 278a370c1766060d2144d6cf0b06c101e1043b6d


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: ff33be9cecee)
6.1.y | Not found
5.15.y | Not found

Note: The patch differs from the upstream commit:
---
1:  278a370c17660 < -:  ------------- gve: Fixes for napi_poll when budget is 0
-:  ------------- > 1:  e087e88ff8e6e gve: Fixes for napi_poll when budget is 0
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y       |  Success    |  Success   |

Re: [PATCH 5.15 v2] gve: Fixes for napi_poll when budget is 0

[Greg KH]

On Tue, Dec 10, 2024 at 11:59:14PM +0000, Ziwei Xiao wrote:
> Netpoll will explicitly pass the polling call with a budget of 0 to
> indicate it's clearing the Tx path only. For the gve_rx_poll and
> gve_xdp_poll, they were mistakenly taking the 0 budget as the indication
> to do all the work. Add check to avoid the rx path and xdp path being
> called when budget is 0. And also avoid napi_complete_done being called
> when budget is 0 for netpoll.
> 
> The original fix was merged here:
> https://lore.kernel.org/r/20231114004144.2022268-1-ziweixiao@google.com
> Resend it since the original one was not cleanly applied to 5.15 kernel.
> 
> commit 278a370c1766 ("gve: Fixes for napi_poll when budget is 0")
> 
> Fixes: f5cedc84a30d ("gve: Add transmit and receive support")
> Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
> Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
> Signed-off-by: Praveen Kaligineedi <pkaligineedi@google.com>
> ---
>  Changes in v2:
>  * Add the original git commit id

In the future, please add it in a way that we can figure it out (see the
hundreds of examples on the mailing list for how it is done.)

thanks,

greg k-h