This is a note to let you know that I've just added the patch titled i40e: Do not enable NAPI on q_vectors that have no rings to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: i40e-do-not-enable-napi-on-q_vectors-that-have-no-rings.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Thu Dec 21 10:35:49 CET 2017 From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> Date: Fri, 24 Mar 2017 15:01:42 -0700 Subject: i40e: Do not enable NAPI on q_vectors that have no rings From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> [ Upstream commit 13a8cd191a2b470cfd435b3b57dbd21aa65ff78c ] When testing the epoll w/ busy poll code I found that I could get into a state where the i40e driver had q_vectors w/ active NAPI that had no rings. This was resulting in a divide by zero error. To correct it I am updating the driver code so that we only support NAPI on q_vectors that have 1 or more rings allocated to them. Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> Tested-by: Andrew Bowers <andrewx.bowers@xxxxxxxxx> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/ethernet/intel/i40e/i40e_main.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) --- a/drivers/net/ethernet/intel/i40e/i40e_main.c +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c @@ -4201,8 +4201,12 @@ static void i40e_napi_enable_all(struct if (!vsi->netdev) return; - for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) - napi_enable(&vsi->q_vectors[q_idx]->napi); + for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) { + struct i40e_q_vector *q_vector = vsi->q_vectors[q_idx]; + + if (q_vector->rx.ring || q_vector->tx.ring) + napi_enable(&q_vector->napi); + } } /** @@ -4216,8 +4220,12 @@ static void i40e_napi_disable_all(struct if (!vsi->netdev) return; - for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) - napi_disable(&vsi->q_vectors[q_idx]->napi); + for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) { + struct i40e_q_vector *q_vector = vsi->q_vectors[q_idx]; + + if (q_vector->rx.ring || q_vector->tx.ring) + napi_disable(&q_vector->napi); + } } /** Patches currently in stable-queue which might be from alexander.h.duyck@xxxxxxxxx are queue-4.4/i40e-do-not-enable-napi-on-q_vectors-that-have-no-rings.patch queue-4.4/net-do-not-allow-negative-values-for-busy_read-and-busy_poll-sysctl-interfaces.patch