This reverts commit 4d4ac2ececd3c42a08dd32a6e3a4aaf25f7efe44.
When the following snippet is run, lockdep will complain[1].
/* Acquire all queues dim_locks */
for (i = 0; i < vi->max_queue_pairs; i++)
mutex_lock(&vi->rq[i].dim_lock);
At the same time, too many queues will cause lockdep to be more irritable,
which can be alleviated by using mutex_lock_nested(), however, there are
still new warning when the number of queues exceeds MAX_LOCKDEP_SUBCLASSES.
So I would like to gently revert this commit, although it brings
unsynchronization that is not so concerned:
1. When dim is enabled, rx_dim_work may modify the coalescing parameters.
Users may read dirty coalescing parameters if querying.
2. When dim is switched from enabled to disabled, a spurious dim worker
maybe scheduled, but this can be handled correctly by rx_dim_work.
[1]
========================================================
WARNING: possible recursive locking detected
6.9.0-rc7+ #319 Not tainted
--------------------------------------------
ethtool/962 is trying to acquire lock:
but task is already holding lock:
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&vi->rq[i].dim_lock);
lock(&vi->rq[i].dim_lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
3 locks held by ethtool/962:
#0: ffffffff82dbaab0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40
#1: ffffffff82dad0a8 (rtnl_mutex){+.+.}-{3:3}, at:
ethnl_default_set_doit+0xbe/0x1e0
stack backtrace:
CPU: 6 PID: 962 Comm: ethtool Not tainted 6.9.0-rc7+ #319
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x79/0xb0
check_deadlock+0x130/0x220
__lock_acquire+0x861/0x990
lock_acquire.part.0+0x72/0x1d0
? lock_acquire+0xf8/0x130
__mutex_lock+0x71/0xd50
virtnet_set_coalesce+0x151/0x190
__ethnl_set_coalesce.isra.0+0x3f8/0x4d0
ethnl_set_coalesce+0x34/0x90
ethnl_default_set_doit+0xdd/0x1e0
genl_family_rcv_msg_doit+0xdc/0x130
genl_family_rcv_msg+0x154/0x230
? __pfx_ethnl_default_set_doit+0x10/0x10
genl_rcv_msg+0x4b/0xa0
? __pfx_genl_rcv_msg+0x10/0x10
netlink_rcv_skb+0x5a/0x110
genl_rcv+0x28/0x40
netlink_unicast+0x1af/0x280
netlink_sendmsg+0x20e/0x460
__sys_sendto+0x1fe/0x210
? find_held_lock+0x2b/0x80
? do_user_addr_fault+0x3a2/0x8a0
? __lock_release+0x5e/0x160
? do_user_addr_fault+0x3a2/0x8a0
? lock_release+0x72/0x140
? do_user_addr_fault+0x3a7/0x8a0
__x64_sys_sendto+0x29/0x30
do_syscall_64+0x78/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 53 +++++++++-------------------------------
1 file changed, 12 insertions(+), 41 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 1cad06cef230..e4a1dff2a64a 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -316,9 +316,6 @@ struct receive_queue {
/* Is dynamic interrupt moderation enabled? */
bool dim_enabled;
- /* Used to protect dim_enabled and inter_coal */
- struct mutex dim_lock;
-
/* Dynamic Interrupt Moderation */
struct dim dim;
@@ -2368,10 +2365,6 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
/* Out of packets? */
if (received < budget) {
napi_complete = virtqueue_napi_complete(napi, rq->vq, received);
- /* Intentionally not taking dim_lock here. This may result in a
- * spurious net_dim call. But if that happens virtnet_rx_dim_work
- * will not act on the scheduled work.
- */
if (napi_complete && rq->dim_enabled)
virtnet_rx_dim_update(vi, rq);
}
@@ -3247,11 +3240,9 @@ static int virtnet_set_ringparam(struct net_device *dev,
return err;
/* The reason is same as the transmit virtqueue reset */
- mutex_lock(&vi->rq[i].dim_lock);
err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, i,
vi->intr_coal_rx.max_usecs,
vi->intr_coal_rx.max_packets);
- mutex_unlock(&vi->rq[i].dim_lock);
if (err)
return err;
}
@@ -4257,7 +4248,6 @@ static int virtnet_send_rx_notf_coal_cmds(struct virtnet_info *vi,
struct virtio_net_ctrl_coal_rx *coal_rx __free(kfree) = NULL;
bool rx_ctrl_dim_on = !!ec->use_adaptive_rx_coalesce;
struct scatterlist sgs_rx;
- int ret = 0;
int i;
if (rx_ctrl_dim_on && !virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
@@ -4267,22 +4257,16 @@ static int virtnet_send_rx_notf_coal_cmds(struct virtnet_info *vi,
ec->rx_max_coalesced_frames != vi->intr_coal_rx.max_packets))
return -EINVAL;
- /* Acquire all queues dim_locks */
- for (i = 0; i < vi->max_queue_pairs; i++)
- mutex_lock(&vi->rq[i].dim_lock);
-
if (rx_ctrl_dim_on && !vi->rx_dim_enabled) {
vi->rx_dim_enabled = true;
for (i = 0; i < vi->max_queue_pairs; i++)
vi->rq[i].dim_enabled = true;
- goto unlock;
+ return 0;
}
coal_rx = kzalloc(sizeof(*coal_rx), GFP_KERNEL);
- if (!coal_rx) {
- ret = -ENOMEM;
- goto unlock;
- }
+ if (!coal_rx)
+ return -ENOMEM;
if (!rx_ctrl_dim_on && vi->rx_dim_enabled) {
vi->rx_dim_enabled = false;
@@ -4300,10 +4284,8 @@ static int virtnet_send_rx_notf_coal_cmds(struct virtnet_info *vi,
if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
- &sgs_rx)) {
- ret = -EINVAL;
- goto unlock;
- }
+ &sgs_rx))
+ return -EINVAL;
vi->intr_coal_rx.max_usecs = ec->rx_coalesce_usecs;
vi->intr_coal_rx.max_packets = ec->rx_max_coalesced_frames;
@@ -4311,11 +4293,8 @@ static int virtnet_send_rx_notf_coal_cmds(struct virtnet_info *vi,
vi->rq[i].intr_coal.max_usecs = ec->rx_coalesce_usecs;
vi->rq[i].intr_coal.max_packets = ec->rx_max_coalesced_frames;
}
-unlock:
- for (i = vi->max_queue_pairs - 1; i >= 0; i--)
- mutex_unlock(&vi->rq[i].dim_lock);
- return ret;
+ return 0;
}
static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
@@ -4339,24 +4318,19 @@ static int virtnet_send_rx_notf_coal_vq_cmds(struct virtnet_info *vi,
u16 queue)
{
bool rx_ctrl_dim_on = !!ec->use_adaptive_rx_coalesce;
+ bool cur_rx_dim = vi->rq[queue].dim_enabled;
u32 max_usecs, max_packets;
- bool cur_rx_dim;
int err;
- mutex_lock(&vi->rq[queue].dim_lock);
- cur_rx_dim = vi->rq[queue].dim_enabled;
max_usecs = vi->rq[queue].intr_coal.max_usecs;
max_packets = vi->rq[queue].intr_coal.max_packets;
if (rx_ctrl_dim_on && (ec->rx_coalesce_usecs != max_usecs ||
- ec->rx_max_coalesced_frames != max_packets)) {
- mutex_unlock(&vi->rq[queue].dim_lock);
+ ec->rx_max_coalesced_frames != max_packets))
return -EINVAL;
- }
if (rx_ctrl_dim_on && !cur_rx_dim) {
vi->rq[queue].dim_enabled = true;
- mutex_unlock(&vi->rq[queue].dim_lock);
return 0;
}
@@ -4369,8 +4343,10 @@ static int virtnet_send_rx_notf_coal_vq_cmds(struct virtnet_info *vi,
err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, queue,
ec->rx_coalesce_usecs,
ec->rx_max_coalesced_frames);
- mutex_unlock(&vi->rq[queue].dim_lock);
- return err;
+ if (err)
+ return err;
+
+ return 0;
}
static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
@@ -4404,7 +4380,6 @@ static void virtnet_rx_dim_work(struct work_struct *work)
qnum = rq - vi->rq;
- mutex_lock(&rq->dim_lock);
if (!rq->dim_enabled)
goto out;
@@ -4420,7 +4395,6 @@ static void virtnet_rx_dim_work(struct work_struct *work)
}
out:
dim->state = DIM_START_MEASURE;
- mutex_unlock(&rq->dim_lock);
}
static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
@@ -4558,13 +4532,11 @@ static int virtnet_get_per_queue_coalesce(struct net_device *dev,
return -EINVAL;
if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
- mutex_lock(&vi->rq[queue].dim_lock);
ec->rx_coalesce_usecs = vi->rq[queue].intr_coal.max_usecs;
ec->tx_coalesce_usecs = vi->sq[queue].intr_coal.max_usecs;
ec->tx_max_coalesced_frames = vi->sq[queue].intr_coal.max_packets;
ec->rx_max_coalesced_frames = vi->rq[queue].intr_coal.max_packets;
ec->use_adaptive_rx_coalesce = vi->rq[queue].dim_enabled;
- mutex_unlock(&vi->rq[queue].dim_lock);
} else {
ec->rx_max_coalesced_frames = 1;
@@ -5396,7 +5368,6 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
u64_stats_init(&vi->rq[i].stats.syncp);
u64_stats_init(&vi->sq[i].stats.syncp);
- mutex_init(&vi->rq[i].dim_lock);
}
return 0;
--
2.32.0.3.g01195cf9f
