| Message ID | 20240208005725.65134-2-shannon.nelson@amd.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | ionic: add XDP support | expand |
On Wed, 7 Feb 2024 16:57:16 -0800 Shannon Nelson wrote: > We should be doing as little as possible besides freeing Tx > space when our napi routines are called with budget of 0, so > jump out before doing anything besides Tx cleaning. > > See commit afbed3f74830 ("net/mlx5e: do as little as possible in napi > poll when budget is 0") for more info. Unfortunately to commit you quote proves that this is a real bug which can crash a non trivial number of machines if kernel printks meet an XDP workload :( This really should go to net.
On 2/9/2024 2:09 PM, Jakub Kicinski wrote: > > On Wed, 7 Feb 2024 16:57:16 -0800 Shannon Nelson wrote: >> We should be doing as little as possible besides freeing Tx >> space when our napi routines are called with budget of 0, so >> jump out before doing anything besides Tx cleaning. >> >> See commit afbed3f74830 ("net/mlx5e: do as little as possible in napi >> poll when budget is 0") for more info. > > Unfortunately to commit you quote proves that this is a real bug which > can crash a non trivial number of machines if kernel printks meet an XDP > workload :( This really should go to net. Sure - I'll repackage that and send it back out. sln
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c index 54cd96b035d6..6f4776759863 100644 --- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c +++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c @@ -579,6 +579,9 @@ int ionic_tx_napi(struct napi_struct *napi, int budget) work_done = ionic_cq_service(cq, budget, ionic_tx_service, NULL, NULL); + if (unlikely(!budget)) + return budget; + if (work_done < budget && napi_complete_done(napi, work_done)) { ionic_dim_update(qcq, IONIC_LIF_F_TX_DIM_INTR); flags |= IONIC_INTR_CRED_UNMASK; @@ -607,6 +610,9 @@ int ionic_rx_napi(struct napi_struct *napi, int budget) u32 work_done = 0; u32 flags = 0; + if (unlikely(!budget)) + return budget; + lif = cq->bound_q->lif; idev = &lif->ionic->idev; @@ -656,6 +662,9 @@ int ionic_txrx_napi(struct napi_struct *napi, int budget) tx_work_done = ionic_cq_service(txcq, IONIC_TX_BUDGET_DEFAULT, ionic_tx_service, NULL, NULL); + if (unlikely(!budget)) + return budget; + rx_work_done = ionic_cq_service(rxcq, budget, ionic_rx_service, NULL, NULL);
We should be doing as little as possible besides freeing Tx space when our napi routines are called with budget of 0, so jump out before doing anything besides Tx cleaning. See commit afbed3f74830 ("net/mlx5e: do as little as possible in napi poll when budget is 0") for more info. Signed-off-by: Shannon Nelson <shannon.nelson@amd.com> Reviewed-by: Brett Creeley <brett.creeley@amd.com> --- drivers/net/ethernet/pensando/ionic/ionic_txrx.c | 9 +++++++++ 1 file changed, 9 insertions(+)