Re: [PATCH net-next] tg3: Link IRQs to NAPI instances

From: Brett Creeley
Date: Thu Sep 12 2024 - 13:51:15 EST




On 9/12/2024 8:58 AM, Joe Damato wrote:
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Link IRQs to NAPI instances with netif_napi_set_irq. This information
can be queried with the netdev-genl API.

Compare the output of /proc/interrupts for my tg3 device with the output of
netdev-genl after applying this patch:

$ cat /proc/interrupts | grep eth0 | cut -f1 --delimiter=':'
331
332
333
334
335

$ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
--dump napi-get --json='{"ifindex": 2}'

[{'id': 149, 'ifindex': 2, 'irq': 335},
{'id': 148, 'ifindex': 2, 'irq': 334},
{'id': 147, 'ifindex': 2, 'irq': 333},
{'id': 146, 'ifindex': 2, 'irq': 332},
{'id': 145, 'ifindex': 2, 'irq': 331}]

Signed-off-by: Joe Damato <jdamato@xxxxxxxxxx>
---
drivers/net/ethernet/broadcom/tg3.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 378815917741..c187b13ab3e6 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -7393,6 +7393,14 @@ static int tg3_poll(struct napi_struct *napi, int budget)
return work_done;
}

+static void tg3_napi_set_irq(struct tg3 *tp)
+{
+ int i;
+
+ for (i = 0; i < tp->irq_cnt; i++)
+ netif_napi_set_irq(&tp->napi[i].napi, tp->napi[i].irq_vec);
+}
+
static void tg3_napi_disable(struct tg3 *tp)
{
int i;
@@ -11652,7 +11660,7 @@ static int tg3_start(struct tg3 *tp, bool reset_phy, bool test_irq,
goto out_ints_fini;

tg3_napi_init(tp);
-
+ tg3_napi_set_irq(tp);

I haven't used this API yet, so I was trying to figure out if this is the right place to call it. I think it is, but other examples may not have put it in the right place.

I think there is a minor bug in fbnic/fbnic_txrx.c. I say this based on the following:

fbnic_alloc_napi_vector() {
<snip>
-> netif_napi_set_irq() # napi->irq = irq
-> netif_napi_add()
-> netif_napi_add_weight() # napi->irq = -1
<snip>
}

Just as an FYI I submitted a patch to fix this just now based on reviewing your code:

https://lore.kernel.org/netdev/20240912174922.10550-1-brett.creeley@xxxxxxx/T/#u

LGTM.

Reviewed-by: Brett Creeley <brett.creeley@xxxxxxx>

tg3_napi_enable(tp);

for (i = 0; i < tp->irq_cnt; i++) {
--
2.25.1