[v3,1/5] failsafe: fix segfault on hotplug event
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Commit Message
When the failsafe PMD encounters a hotplug event, it switches its rx/tx
functions to "safe" ones that validate the sub-device's rx/tx functions
before calling them. It switches the rx/tx functions by changing the
function pointers in the rte_eth_dev structure.
Following commit 7a0935239b9e, the rx/tx functions of PMDs are no longer
called through the function pointers in the rte_eth_dev structure. They
are rather called through a flat array named rte_eth_fp_ops. The
function pointers in that array are initialized when the devices start
and are initialized.
When a hotplug event occurs, the function pointers in rte_eth_fp_ops
still point to the "unsafe" rx/tx functions in the failsafe PMD since
they haven't been updated. This results in a segmentation fault because
it ends up using the "unsafe" functions, when the "safe" functions
should have been used.
To fix the problem, the "unsafe" rx/tx functions were completely
removed. The "safe" functions are now always used. Modifying the rx/tx
functions on-the-fly is not supported by DPDK, so this is the correct
approach and should have very minimal impact on performance.
Fixes: 7a0935239b9e ("ethdev: make fast-path functions to use new flat array")
Cc: Konstantin Ananyev <konstantin.ananyev@huawei.com>
Cc: stable@dpdk.org
Signed-off-by: Luc Pelletier <lucp.at.work@gmail.com>
---
drivers/net/failsafe/failsafe_ether.c | 2 -
drivers/net/failsafe/failsafe_private.h | 8 ---
drivers/net/failsafe/failsafe_rxtx.c | 83 +------------------------
3 files changed, 1 insertion(+), 92 deletions(-)
Comments
On Tue, 29 Nov 2022 09:48:29 -0500
Luc Pelletier <lucp.at.work@gmail.com> wrote:
> When the failsafe PMD encounters a hotplug event, it switches its rx/tx
> functions to "safe" ones that validate the sub-device's rx/tx functions
> before calling them. It switches the rx/tx functions by changing the
> function pointers in the rte_eth_dev structure.
>
> Following commit 7a0935239b9e, the rx/tx functions of PMDs are no longer
> called through the function pointers in the rte_eth_dev structure. They
> are rather called through a flat array named rte_eth_fp_ops. The
> function pointers in that array are initialized when the devices start
> and are initialized.
>
> When a hotplug event occurs, the function pointers in rte_eth_fp_ops
> still point to the "unsafe" rx/tx functions in the failsafe PMD since
> they haven't been updated. This results in a segmentation fault because
> it ends up using the "unsafe" functions, when the "safe" functions
> should have been used.
>
> To fix the problem, the "unsafe" rx/tx functions were completely
> removed. The "safe" functions are now always used. Modifying the rx/tx
> functions on-the-fly is not supported by DPDK, so this is the correct
> approach and should have very minimal impact on performance.
>
> Fixes: 7a0935239b9e ("ethdev: make fast-path functions to use new flat array")
> Cc: Konstantin Ananyev <konstantin.ananyev@huawei.com>
> Cc: stable@dpdk.org
>
> Signed-off-by: Luc Pelletier <lucp.at.work@gmail.com>
I don't use or have way to test failsafe anymore.
But wanted to give a try at reviewing this.
This version does not apply to current code base.
If still interested, please rebase and resubmit.
@@ -595,8 +595,6 @@ failsafe_eth_rmv_event_callback(uint16_t port_id __rte_unused,
fs_lock(fs_dev(sdev), 0);
/* Switch as soon as possible tx_dev. */
fs_switch_dev(fs_dev(sdev), sdev);
- /* Use safe bursts in any case. */
- failsafe_set_burst_fn(fs_dev(sdev), 1);
/*
* Async removal, the sub-PMD will try to unregister
* the callback at the source of the current thread context.
@@ -208,18 +208,11 @@ int failsafe_hotplug_alarm_cancel(struct rte_eth_dev *dev);
/* RX / TX */
-void failsafe_set_burst_fn(struct rte_eth_dev *dev, int force_safe);
-
uint16_t failsafe_rx_burst(void *rxq,
struct rte_mbuf **rx_pkts, uint16_t nb_pkts);
uint16_t failsafe_tx_burst(void *txq,
struct rte_mbuf **tx_pkts, uint16_t nb_pkts);
-uint16_t failsafe_rx_burst_fast(void *rxq,
- struct rte_mbuf **rx_pkts, uint16_t nb_pkts);
-uint16_t failsafe_tx_burst_fast(void *txq,
- struct rte_mbuf **tx_pkts, uint16_t nb_pkts);
-
/* ARGS */
int failsafe_args_parse(struct rte_eth_dev *dev, const char *params);
@@ -487,7 +480,6 @@ fs_switch_dev(struct rte_eth_dev *dev,
} else {
return;
}
- failsafe_set_burst_fn(dev, 0);
rte_wmb();
}
@@ -28,39 +28,6 @@ fs_tx_unsafe(struct sub_device *sdev)
(sdev->state != DEV_STARTED);
}
-void
-failsafe_set_burst_fn(struct rte_eth_dev *dev, int force_safe)
-{
- struct sub_device *sdev;
- uint8_t i;
- int need_safe;
- int safe_set;
-
- need_safe = force_safe;
- FOREACH_SUBDEV(sdev, i, dev)
- need_safe |= fs_rx_unsafe(sdev);
- safe_set = (dev->rx_pkt_burst == &failsafe_rx_burst);
- if (need_safe && !safe_set) {
- DEBUG("Using safe RX bursts%s",
- (force_safe ? " (forced)" : ""));
- dev->rx_pkt_burst = &failsafe_rx_burst;
- } else if (!need_safe && safe_set) {
- DEBUG("Using fast RX bursts");
- dev->rx_pkt_burst = &failsafe_rx_burst_fast;
- }
- need_safe = force_safe || fs_tx_unsafe(TX_SUBDEV(dev));
- safe_set = (dev->tx_pkt_burst == &failsafe_tx_burst);
- if (need_safe && !safe_set) {
- DEBUG("Using safe TX bursts%s",
- (force_safe ? " (forced)" : ""));
- dev->tx_pkt_burst = &failsafe_tx_burst;
- } else if (!need_safe && safe_set) {
- DEBUG("Using fast TX bursts");
- dev->tx_pkt_burst = &failsafe_tx_burst_fast;
- }
- rte_wmb();
-}
-
/*
* Override source port in Rx packets.
*
@@ -89,7 +56,7 @@ failsafe_rx_burst(void *queue,
rxq = queue;
sdev = rxq->sdev;
do {
- if (fs_rx_unsafe(sdev)) {
+ if (unlikely(fs_rx_unsafe(sdev))) {
nb_rx = 0;
sdev = sdev->next;
continue;
@@ -108,34 +75,6 @@ failsafe_rx_burst(void *queue,
return nb_rx;
}
-uint16_t
-failsafe_rx_burst_fast(void *queue,
- struct rte_mbuf **rx_pkts,
- uint16_t nb_pkts)
-{
- struct sub_device *sdev;
- struct rxq *rxq;
- void *sub_rxq;
- uint16_t nb_rx;
-
- rxq = queue;
- sdev = rxq->sdev;
- do {
- RTE_ASSERT(!fs_rx_unsafe(sdev));
- sub_rxq = ETH(sdev)->data->rx_queues[rxq->qid];
- FS_ATOMIC_P(rxq->refcnt[sdev->sid]);
- nb_rx = ETH(sdev)->
- rx_pkt_burst(sub_rxq, rx_pkts, nb_pkts);
- FS_ATOMIC_V(rxq->refcnt[sdev->sid]);
- sdev = sdev->next;
- } while (nb_rx == 0 && sdev != rxq->sdev);
- rxq->sdev = sdev;
- if (nb_rx)
- failsafe_rx_set_port(rx_pkts, nb_rx,
- rxq->priv->data->port_id);
- return nb_rx;
-}
-
uint16_t
failsafe_tx_burst(void *queue,
struct rte_mbuf **tx_pkts,
@@ -156,23 +95,3 @@ failsafe_tx_burst(void *queue,
FS_ATOMIC_V(txq->refcnt[sdev->sid]);
return nb_tx;
}
-
-uint16_t
-failsafe_tx_burst_fast(void *queue,
- struct rte_mbuf **tx_pkts,
- uint16_t nb_pkts)
-{
- struct sub_device *sdev;
- struct txq *txq;
- void *sub_txq;
- uint16_t nb_tx;
-
- txq = queue;
- sdev = TX_SUBDEV(&rte_eth_devices[txq->priv->data->port_id]);
- RTE_ASSERT(!fs_tx_unsafe(sdev));
- sub_txq = ETH(sdev)->data->tx_queues[txq->qid];
- FS_ATOMIC_P(txq->refcnt[sdev->sid]);
- nb_tx = ETH(sdev)->tx_pkt_burst(sub_txq, tx_pkts, nb_pkts);
- FS_ATOMIC_V(txq->refcnt[sdev->sid]);
- return nb_tx;
-}