mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git
synced 2026-10-31 14:23:49 +01:00
Jorijn van der Graaf
3cbfd627ee
ipa_start_xmit() unconditionally stops the TX queue before calling
pm_runtime_get(), relying on the wake scheduled by runtime resume
(ipa_modem_wake_queue_work()) to restart it once power is ACTIVE.
But that work is queued from within the runtime resume callback,
before the device's power state reaches RPM_ACTIVE, so it can run
while the device is still RPM_RESUMING. The wake is then consumed
too early: the transmit it restarts stops the queue again,
pm_runtime_get() returns -EINPROGRESS without arranging any future
wake (deferred_resume exists only for RPM_SUSPENDING), and after the
resume completes nothing is left to wake the queue. Transmit stalls
permanently: packets pile up in the qdisc behind the stopped queue,
the device runtime-suspends, and since the netdev registers no
ndo_tx_timeout the watchdog never fires. Observed on SM7635
(Fairphone 6) as the cellular data path going permanently deaf
within hours, RX included, since nothing resumes the suspended
endpoints.
Close the window by making the wake work wait for the resume to
complete (pm_runtime_get_sync()) before waking the queue. Every
queue stop is then guaranteed a later wake that happens while power
is ACTIVE; a transmit racing a new suspend/resume cycle re-schedules
the work. If the device could not be resumed, wake the queue anyway
so pending packets are dropped by the transmit path rather than
stranded.
The STARTED power flag used to narrow this window: a wake running
before the transmit path's stop suppressed that stop, but only once,
as the flag was cleared by the first stop it absorbed. Removing the
flag made a single transmit during an in-flight resume sufficient to
strand the queue, which is the form observed.
With an accelerated reproducer (autosuspend delay shortened to 5 ms,
~20 packets/s of TX), an unpatched kernel stalled three times in
230 s / 4380 packets; with this patch the same test ran 3601 s /
70298 packets without a stall.
Fixes: 688de12f08 ("net: ipa: kill the STARTED IPA power flag")
Cc: [email protected]
Signed-off-by: Jorijn van der Graaf <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>
515 lines
13 KiB
C
515 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
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* Copyright (C) 2018-2024 Linaro Ltd.
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*/
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#include <linux/errno.h>
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#include <linux/etherdevice.h>
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#include <linux/if_arp.h>
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#include <linux/if_rmnet.h>
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#include <linux/netdevice.h>
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#include <linux/pm_runtime.h>
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#include <linux/skbuff.h>
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#include <net/pkt_sched.h>
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#include <linux/remoteproc/qcom_rproc.h>
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#include "ipa.h"
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#include "ipa_endpoint.h"
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#include "ipa_mem.h"
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#include "ipa_modem.h"
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#include "ipa_smp2p.h"
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#include "ipa_table.h"
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#include "ipa_uc.h"
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#define IPA_NETDEV_NAME "rmnet_ipa%d"
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#define IPA_NETDEV_TAILROOM 0 /* for padding by mux layer */
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#define IPA_NETDEV_TIMEOUT 10 /* seconds */
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enum ipa_modem_state {
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IPA_MODEM_STATE_STOPPED = 0,
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IPA_MODEM_STATE_STARTING,
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IPA_MODEM_STATE_RUNNING,
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IPA_MODEM_STATE_STOPPING,
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};
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/**
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* struct ipa_priv - IPA network device private data
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* @ipa: IPA pointer
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* @tx: Transmit endpoint pointer
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* @rx: Receive endpoint pointer
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* @work: Work structure used to wake the modem netdev TX queue
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*/
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struct ipa_priv {
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struct ipa *ipa;
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struct ipa_endpoint *tx;
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struct ipa_endpoint *rx;
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struct work_struct work;
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};
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/** ipa_open() - Opens the modem network interface */
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static int ipa_open(struct net_device *netdev)
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{
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struct ipa_priv *priv = netdev_priv(netdev);
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struct ipa *ipa = priv->ipa;
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struct device *dev;
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int ret;
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dev = ipa->dev;
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ret = pm_runtime_get_sync(dev);
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if (ret < 0)
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goto err_power_put;
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ret = ipa_endpoint_enable_one(priv->tx);
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if (ret)
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goto err_power_put;
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ret = ipa_endpoint_enable_one(priv->rx);
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if (ret)
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goto err_disable_tx;
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netif_start_queue(netdev);
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(void)pm_runtime_put_autosuspend(dev);
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return 0;
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err_disable_tx:
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ipa_endpoint_disable_one(priv->tx);
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err_power_put:
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pm_runtime_put_noidle(dev);
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return ret;
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}
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/** ipa_stop() - Stops the modem network interface. */
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static int ipa_stop(struct net_device *netdev)
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{
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struct ipa_priv *priv = netdev_priv(netdev);
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struct ipa *ipa = priv->ipa;
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struct device *dev;
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int ret;
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dev = ipa->dev;
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ret = pm_runtime_get_sync(dev);
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if (ret < 0)
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goto out_power_put;
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netif_stop_queue(netdev);
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ipa_endpoint_disable_one(priv->rx);
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ipa_endpoint_disable_one(priv->tx);
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out_power_put:
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(void)pm_runtime_put_autosuspend(dev);
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return 0;
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}
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/** ipa_start_xmit() - Transmit an skb
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* @skb: Socket buffer to be transmitted
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* @netdev: Network device
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*
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* Return: NETDEV_TX_OK if successful (or dropped), NETDEV_TX_BUSY otherwise
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* Normally NETDEV_TX_OK indicates the buffer was successfully transmitted.
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* If the buffer has an unexpected protocol or its size is out of range it
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* is quietly dropped, returning NETDEV_TX_OK. NETDEV_TX_BUSY indicates
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* the buffer cannot be sent at this time and should retried later.
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*/
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static netdev_tx_t
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ipa_start_xmit(struct sk_buff *skb, struct net_device *netdev)
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{
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struct net_device_stats *stats = &netdev->stats;
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struct ipa_priv *priv = netdev_priv(netdev);
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struct ipa_endpoint *endpoint;
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struct ipa *ipa = priv->ipa;
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u32 skb_len = skb->len;
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struct device *dev;
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int ret;
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if (!skb_len)
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goto err_drop_skb;
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endpoint = ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX];
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if (endpoint->config.qmap && skb->protocol != htons(ETH_P_MAP))
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goto err_drop_skb;
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/* The hardware must be powered for us to transmit, so if we're not
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* ready we want the network stack to stop queueing until power is
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* ACTIVE. Once runtime resume has completed, we inform the network
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* stack it's OK to try transmitting again.
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*
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* We learn from pm_runtime_get() whether the hardware is powered.
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* If it was not, powering up is either started or already underway.
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* And in that case we want to disable queueing, expecting it to be
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* re-enabled once power is ACTIVE. But runtime PM and network
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* transmit run concurrently, and if we're not careful the requests
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* to stop and start queueing could occur in the wrong order.
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*
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* For that reason we *always* stop queueing here, *before* the call
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* to pm_runtime_get(). If we determine here that power is ACTIVE,
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* we restart queueing before transmitting the SKB. Otherwise
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* queueing will eventually be enabled after resume completes.
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*/
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netif_stop_queue(netdev);
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dev = ipa->dev;
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ret = pm_runtime_get(dev);
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if (ret < 1) {
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/* If a resume won't happen, just drop the packet */
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if (ret < 0 && ret != -EINPROGRESS) {
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netif_wake_queue(netdev);
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pm_runtime_put_noidle(dev);
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goto err_drop_skb;
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}
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pm_runtime_put_noidle(dev);
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return NETDEV_TX_BUSY;
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}
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netif_wake_queue(netdev);
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ret = ipa_endpoint_skb_tx(endpoint, skb);
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(void)pm_runtime_put_autosuspend(dev);
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if (ret) {
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if (ret != -E2BIG)
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return NETDEV_TX_BUSY;
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goto err_drop_skb;
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}
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stats->tx_packets++;
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stats->tx_bytes += skb_len;
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return NETDEV_TX_OK;
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err_drop_skb:
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dev_kfree_skb_any(skb);
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stats->tx_dropped++;
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return NETDEV_TX_OK;
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}
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void ipa_modem_skb_rx(struct net_device *netdev, struct sk_buff *skb)
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{
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struct net_device_stats *stats = &netdev->stats;
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if (skb) {
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skb->dev = netdev;
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skb->protocol = htons(ETH_P_MAP);
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stats->rx_packets++;
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stats->rx_bytes += skb->len;
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(void)netif_receive_skb(skb);
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} else {
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stats->rx_dropped++;
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}
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}
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static const struct net_device_ops ipa_modem_ops = {
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.ndo_open = ipa_open,
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.ndo_stop = ipa_stop,
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.ndo_start_xmit = ipa_start_xmit,
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};
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/** ipa_modem_netdev_setup() - netdev setup function for the modem */
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static void ipa_modem_netdev_setup(struct net_device *netdev)
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{
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netdev->netdev_ops = &ipa_modem_ops;
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netdev->header_ops = NULL;
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netdev->type = ARPHRD_RAWIP;
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netdev->hard_header_len = 0;
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netdev->min_header_len = ETH_HLEN;
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netdev->min_mtu = ETH_MIN_MTU;
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netdev->max_mtu = IPA_MTU;
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netdev->mtu = netdev->max_mtu;
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netdev->addr_len = 0;
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netdev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
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netdev->flags &= ~(IFF_BROADCAST | IFF_MULTICAST);
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netdev->priv_flags |= IFF_TX_SKB_SHARING;
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eth_broadcast_addr(netdev->broadcast);
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/* The endpoint is configured for QMAP */
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netdev->needed_headroom = sizeof(struct rmnet_map_header);
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netdev->needed_tailroom = IPA_NETDEV_TAILROOM;
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netdev->watchdog_timeo = IPA_NETDEV_TIMEOUT * HZ;
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netdev->hw_features = NETIF_F_SG;
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}
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/** ipa_modem_suspend() - suspend callback
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* @netdev: Network device
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*
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* Suspend the modem's endpoints.
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*/
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void ipa_modem_suspend(struct net_device *netdev)
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{
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struct ipa_priv *priv;
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if (!(netdev->flags & IFF_UP))
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return;
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priv = netdev_priv(netdev);
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ipa_endpoint_suspend_one(priv->rx);
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ipa_endpoint_suspend_one(priv->tx);
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}
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/**
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* ipa_modem_wake_queue_work() - enable modem netdev queue
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* @work: Work structure
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*
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* Re-enable transmit on the modem network device. This is called
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* in (power management) work queue context, scheduled when resuming
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* the modem. We can't enable the queue directly in ipa_modem_resume()
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* because transmits restart the instant the queue is awakened; but the
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* device power state won't be ACTIVE until *after* ipa_modem_resume()
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* returns. A transmit restarted before that would stop the queue
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* again and get -EINPROGRESS from pm_runtime_get(), and with this
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* work having already run, nothing would ever wake the queue again.
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* So wait for the resume to complete before waking the queue.
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*/
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static void ipa_modem_wake_queue_work(struct work_struct *work)
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{
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struct ipa_priv *priv = container_of(work, struct ipa_priv, work);
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struct device *dev = priv->ipa->dev;
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int ret;
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ret = pm_runtime_get_sync(dev);
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/* Wake the queue even if the device could not be resumed, so
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* that pending packets are dropped by the transmit path rather
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* than stranded behind a stopped queue.
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*/
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netif_wake_queue(priv->tx->netdev);
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if (ret < 0)
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pm_runtime_put_noidle(dev);
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else
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(void)pm_runtime_put_autosuspend(dev);
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}
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/** ipa_modem_resume() - resume callback for runtime_pm
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* @dev: pointer to device
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*
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* Resume the modem's endpoints.
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*/
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void ipa_modem_resume(struct net_device *netdev)
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{
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struct ipa_priv *priv;
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if (!(netdev->flags & IFF_UP))
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return;
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priv = netdev_priv(netdev);
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ipa_endpoint_resume_one(priv->tx);
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ipa_endpoint_resume_one(priv->rx);
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/* Arrange for the TX queue to be restarted */
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(void)queue_pm_work(&priv->work);
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}
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int ipa_modem_start(struct ipa *ipa)
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{
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enum ipa_modem_state state;
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struct net_device *netdev;
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struct ipa_priv *priv;
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int ret;
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/* Only attempt to start the modem if it's stopped */
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state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_STOPPED,
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IPA_MODEM_STATE_STARTING);
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/* Silently ignore attempts when running, or when changing state */
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if (state != IPA_MODEM_STATE_STOPPED)
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return 0;
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netdev = alloc_netdev(sizeof(struct ipa_priv), IPA_NETDEV_NAME,
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NET_NAME_UNKNOWN, ipa_modem_netdev_setup);
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if (!netdev) {
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ret = -ENOMEM;
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goto out_set_state;
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}
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SET_NETDEV_DEV(netdev, ipa->dev);
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priv = netdev_priv(netdev);
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priv->ipa = ipa;
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priv->tx = ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX];
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priv->rx = ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX];
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INIT_WORK(&priv->work, ipa_modem_wake_queue_work);
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priv->tx->netdev = netdev;
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priv->rx->netdev = netdev;
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ipa->modem_netdev = netdev;
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ret = register_netdev(netdev);
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if (ret) {
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ipa->modem_netdev = NULL;
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priv->rx->netdev = NULL;
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priv->tx->netdev = NULL;
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free_netdev(netdev);
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}
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out_set_state:
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if (ret)
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atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
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else
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atomic_set(&ipa->modem_state, IPA_MODEM_STATE_RUNNING);
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smp_mb__after_atomic();
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return ret;
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}
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int ipa_modem_stop(struct ipa *ipa)
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{
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struct net_device *netdev = ipa->modem_netdev;
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enum ipa_modem_state state;
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/* Only attempt to stop the modem if it's running */
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state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_RUNNING,
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IPA_MODEM_STATE_STOPPING);
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/* Silently ignore attempts when already stopped */
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if (state == IPA_MODEM_STATE_STOPPED)
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return 0;
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/* If we're somewhere between stopped and starting, we're busy */
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if (state != IPA_MODEM_STATE_RUNNING)
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return -EBUSY;
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/* Clean up the netdev and endpoints if it was started */
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if (netdev) {
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struct ipa_priv *priv = netdev_priv(netdev);
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cancel_work_sync(&priv->work);
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/* If it was opened, stop it first */
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if (netdev->flags & IFF_UP)
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(void)ipa_stop(netdev);
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unregister_netdev(netdev);
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ipa->modem_netdev = NULL;
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priv->rx->netdev = NULL;
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priv->tx->netdev = NULL;
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free_netdev(netdev);
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}
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atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
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smp_mb__after_atomic();
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return 0;
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}
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/* Treat a "clean" modem stop the same as a crash */
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static void ipa_modem_crashed(struct ipa *ipa)
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{
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struct device *dev = ipa->dev;
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int ret;
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/* Prevent the modem from triggering a call to ipa_setup() */
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ipa_smp2p_irq_disable_setup(ipa);
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ret = pm_runtime_get_sync(dev);
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if (ret < 0) {
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dev_err(dev, "error %d getting power to handle crash\n", ret);
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goto out_power_put;
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}
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ipa_endpoint_modem_pause_all(ipa, true);
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ipa_endpoint_modem_hol_block_clear_all(ipa);
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ipa_table_reset(ipa, true);
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ret = ipa_table_hash_flush(ipa);
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if (ret)
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dev_err(dev, "error %d flushing hash caches\n", ret);
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ret = ipa_endpoint_modem_exception_reset_all(ipa);
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if (ret)
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dev_err(dev, "error %d resetting exception endpoint\n", ret);
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ipa_endpoint_modem_pause_all(ipa, false);
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ret = ipa_modem_stop(ipa);
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if (ret)
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dev_err(dev, "error %d stopping modem\n", ret);
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/* Now prepare for the next modem boot */
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ret = ipa_mem_zero_modem(ipa);
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if (ret)
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dev_err(dev, "error %d zeroing modem memory regions\n", ret);
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out_power_put:
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(void)pm_runtime_put_autosuspend(dev);
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}
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static int ipa_modem_notify(struct notifier_block *nb, unsigned long action,
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void *data)
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{
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struct ipa *ipa = container_of(nb, struct ipa, nb);
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struct qcom_ssr_notify_data *notify_data = data;
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struct device *dev = ipa->dev;
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switch (action) {
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case QCOM_SSR_BEFORE_POWERUP:
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dev_info(dev, "received modem starting event\n");
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ipa_uc_power(ipa);
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ipa_smp2p_notify_reset(ipa);
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break;
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case QCOM_SSR_AFTER_POWERUP:
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dev_info(dev, "received modem running event\n");
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break;
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case QCOM_SSR_BEFORE_SHUTDOWN:
|
|
dev_info(dev, "received modem %s event\n",
|
|
notify_data->crashed ? "crashed" : "stopping");
|
|
if (ipa->setup_complete)
|
|
ipa_modem_crashed(ipa);
|
|
break;
|
|
|
|
case QCOM_SSR_AFTER_SHUTDOWN:
|
|
dev_info(dev, "received modem offline event\n");
|
|
break;
|
|
|
|
default:
|
|
dev_err(dev, "received unrecognized event %lu\n", action);
|
|
break;
|
|
}
|
|
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
int ipa_modem_config(struct ipa *ipa)
|
|
{
|
|
void *notifier;
|
|
|
|
ipa->nb.notifier_call = ipa_modem_notify;
|
|
|
|
notifier = qcom_register_ssr_notifier("mpss", &ipa->nb);
|
|
if (IS_ERR(notifier))
|
|
return PTR_ERR(notifier);
|
|
|
|
ipa->notifier = notifier;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void ipa_modem_deconfig(struct ipa *ipa)
|
|
{
|
|
struct device *dev = ipa->dev;
|
|
int ret;
|
|
|
|
ret = qcom_unregister_ssr_notifier(ipa->notifier, &ipa->nb);
|
|
if (ret)
|
|
dev_err(dev, "error %d unregistering notifier", ret);
|
|
|
|
ipa->notifier = NULL;
|
|
memset(&ipa->nb, 0, sizeof(ipa->nb));
|
|
}
|