ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 280 insertions, 0 deletions

diff --git a/drivers/net/netdevsim/ethtool.c b/drivers/net/netdevsim/ethtool.c
new file mode 100644
index 000000000..025ea7987
--- /dev/null
+++ b/drivers/net/netdevsim/ethtool.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+
+#include <linux/debugfs.h>
+#include <linux/random.h>
+#include <net/netdev_queues.h>
+
+#include "netdevsim.h"
+
+static void
+nsim_get_pause_stats(struct net_device *dev,
+		     struct ethtool_pause_stats *pause_stats)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	if (ns->ethtool.pauseparam.report_stats_rx)
+		pause_stats->rx_pause_frames = 1;
+	if (ns->ethtool.pauseparam.report_stats_tx)
+		pause_stats->tx_pause_frames = 2;
+}
+
+static void
+nsim_get_pauseparam(struct net_device *dev, struct ethtool_pauseparam *pause)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	pause->autoneg = 0; /* We don't support ksettings, so can't pretend */
+	pause->rx_pause = ns->ethtool.pauseparam.rx;
+	pause->tx_pause = ns->ethtool.pauseparam.tx;
+}
+
+static int
+nsim_set_pauseparam(struct net_device *dev, struct ethtool_pauseparam *pause)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	if (pause->autoneg)
+		return -EINVAL;
+
+	ns->ethtool.pauseparam.rx = pause->rx_pause;
+	ns->ethtool.pauseparam.tx = pause->tx_pause;
+	return 0;
+}
+
+static int nsim_get_coalesce(struct net_device *dev,
+			     struct ethtool_coalesce *coal,
+			     struct kernel_ethtool_coalesce *kernel_coal,
+			     struct netlink_ext_ack *extack)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	memcpy(coal, &ns->ethtool.coalesce, sizeof(ns->ethtool.coalesce));
+	return 0;
+}
+
+static int nsim_set_coalesce(struct net_device *dev,
+			     struct ethtool_coalesce *coal,
+			     struct kernel_ethtool_coalesce *kernel_coal,
+			     struct netlink_ext_ack *extack)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	memcpy(&ns->ethtool.coalesce, coal, sizeof(ns->ethtool.coalesce));
+	return 0;
+}
+
+static void nsim_get_ringparam(struct net_device *dev,
+			       struct ethtool_ringparam *ring,
+			       struct kernel_ethtool_ringparam *kernel_ring,
+			       struct netlink_ext_ack *extack)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	memcpy(ring, &ns->ethtool.ring, sizeof(ns->ethtool.ring));
+	kernel_ring->hds_thresh_max = NSIM_HDS_THRESHOLD_MAX;
+
+	if (dev->cfg->hds_config == ETHTOOL_TCP_DATA_SPLIT_UNKNOWN)
+		kernel_ring->tcp_data_split = ETHTOOL_TCP_DATA_SPLIT_ENABLED;
+}
+
+static int nsim_set_ringparam(struct net_device *dev,
+			      struct ethtool_ringparam *ring,
+			      struct kernel_ethtool_ringparam *kernel_ring,
+			      struct netlink_ext_ack *extack)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	ns->ethtool.ring.rx_pending = ring->rx_pending;
+	ns->ethtool.ring.rx_jumbo_pending = ring->rx_jumbo_pending;
+	ns->ethtool.ring.rx_mini_pending = ring->rx_mini_pending;
+	ns->ethtool.ring.tx_pending = ring->tx_pending;
+	return 0;
+}
+
+static void
+nsim_get_channels(struct net_device *dev, struct ethtool_channels *ch)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	ch->max_combined = ns->nsim_bus_dev->num_queues;
+	ch->combined_count = ns->ethtool.channels;
+}
+
+static void
+nsim_wake_queues(struct net_device *dev)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+	struct netdevsim *peer;
+
+	synchronize_net();
+	netif_tx_wake_all_queues(dev);
+
+	rcu_read_lock();
+	peer = rcu_dereference(ns->peer);
+	if (peer)
+		netif_tx_wake_all_queues(peer->netdev);
+	rcu_read_unlock();
+}
+
+static int
+nsim_set_channels(struct net_device *dev, struct ethtool_channels *ch)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+	int err;
+
+	err = netif_set_real_num_queues(dev, ch->combined_count,
+					ch->combined_count);
+	if (err)
+		return err;
+
+	ns->ethtool.channels = ch->combined_count;
+
+	/* Only wake up queues if devices are linked */
+	if (rcu_access_pointer(ns->peer))
+		nsim_wake_queues(dev);
+
+	return 0;
+}
+
+static int
+nsim_get_fecparam(struct net_device *dev, struct ethtool_fecparam *fecparam)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	if (ns->ethtool.get_err)
+		return -ns->ethtool.get_err;
+	memcpy(fecparam, &ns->ethtool.fec, sizeof(ns->ethtool.fec));
+	return 0;
+}
+
+static int
+nsim_set_fecparam(struct net_device *dev, struct ethtool_fecparam *fecparam)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+	u32 fec;
+
+	if (ns->ethtool.set_err)
+		return -ns->ethtool.set_err;
+	memcpy(&ns->ethtool.fec, fecparam, sizeof(ns->ethtool.fec));
+	fec = fecparam->fec;
+	if (fec == ETHTOOL_FEC_AUTO)
+		fec |= ETHTOOL_FEC_OFF;
+	fec |= ETHTOOL_FEC_NONE;
+	ns->ethtool.fec.active_fec = 1 << (fls(fec) - 1);
+	return 0;
+}
+
+static const struct ethtool_fec_hist_range netdevsim_fec_ranges[] = {
+	{ 0, 0},
+	{ 1, 3},
+	{ 4, 7},
+	{ 0, 0}
+};
+
+static void
+nsim_get_fec_stats(struct net_device *dev, struct ethtool_fec_stats *fec_stats,
+		   struct ethtool_fec_hist *hist)
+{
+	struct ethtool_fec_hist_value *values = hist->values;
+
+	hist->ranges = netdevsim_fec_ranges;
+
+	fec_stats->corrected_blocks.total = 123;
+	fec_stats->uncorrectable_blocks.total = 4;
+
+	values[0].per_lane[0] = 125;
+	values[0].per_lane[1] = 120;
+	values[0].per_lane[2] = 100;
+	values[0].per_lane[3] = 100;
+	values[1].sum = 12;
+	values[2].sum = 2;
+	values[2].per_lane[0] = 2;
+	values[2].per_lane[1] = 0;
+	values[2].per_lane[2] = 0;
+	values[2].per_lane[3] = 0;
+}
+
+static int nsim_get_ts_info(struct net_device *dev,
+			    struct kernel_ethtool_ts_info *info)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	info->phc_index = mock_phc_index(ns->phc);
+
+	return 0;
+}
+
+static const struct ethtool_ops nsim_ethtool_ops = {
+	.supported_coalesce_params	= ETHTOOL_COALESCE_ALL_PARAMS,
+	.supported_ring_params		= ETHTOOL_RING_USE_TCP_DATA_SPLIT |
+					  ETHTOOL_RING_USE_HDS_THRS,
+	.op_needs_rtnl			= ETHTOOL_OP_NEEDS_RTNL_SCHANNELS,
+	.get_pause_stats	        = nsim_get_pause_stats,
+	.get_pauseparam		        = nsim_get_pauseparam,
+	.set_pauseparam		        = nsim_set_pauseparam,
+	.set_coalesce			= nsim_set_coalesce,
+	.get_coalesce			= nsim_get_coalesce,
+	.get_ringparam			= nsim_get_ringparam,
+	.set_ringparam			= nsim_set_ringparam,
+	.get_channels			= nsim_get_channels,
+	.set_channels			= nsim_set_channels,
+	.get_fecparam			= nsim_get_fecparam,
+	.set_fecparam			= nsim_set_fecparam,
+	.get_fec_stats			= nsim_get_fec_stats,
+	.get_ts_info			= nsim_get_ts_info,
+};
+
+static void nsim_ethtool_ring_init(struct netdevsim *ns)
+{
+	ns->ethtool.ring.rx_pending = 512;
+	ns->ethtool.ring.rx_max_pending = 4096;
+	ns->ethtool.ring.rx_jumbo_max_pending = 4096;
+	ns->ethtool.ring.rx_mini_max_pending = 4096;
+	ns->ethtool.ring.tx_pending = 512;
+	ns->ethtool.ring.tx_max_pending = 4096;
+}
+
+void nsim_ethtool_init(struct netdevsim *ns)
+{
+	struct dentry *ethtool, *dir;
+
+	ns->netdev->ethtool_ops = &nsim_ethtool_ops;
+
+	nsim_ethtool_ring_init(ns);
+
+	ns->ethtool.pauseparam.report_stats_rx = true;
+	ns->ethtool.pauseparam.report_stats_tx = true;
+
+	ns->ethtool.fec.fec = ETHTOOL_FEC_NONE;
+	ns->ethtool.fec.active_fec = ETHTOOL_FEC_NONE;
+
+	ns->ethtool.channels = ns->nsim_bus_dev->num_queues;
+
+	ethtool = debugfs_create_dir("ethtool", ns->nsim_dev_port->ddir);
+	ns->ethtool_ddir = ethtool;
+
+	debugfs_create_u32("get_err", 0600, ethtool, &ns->ethtool.get_err);
+	debugfs_create_u32("set_err", 0600, ethtool, &ns->ethtool.set_err);
+
+	dir = debugfs_create_dir("pause", ethtool);
+	debugfs_create_bool("report_stats_rx", 0600, dir,
+			    &ns->ethtool.pauseparam.report_stats_rx);
+	debugfs_create_bool("report_stats_tx", 0600, dir,
+			    &ns->ethtool.pauseparam.report_stats_tx);
+
+	dir = debugfs_create_dir("ring", ethtool);
+	debugfs_create_u32("rx_max_pending", 0600, dir,
+			   &ns->ethtool.ring.rx_max_pending);
+	debugfs_create_u32("rx_jumbo_max_pending", 0600, dir,
+			   &ns->ethtool.ring.rx_jumbo_max_pending);
+	debugfs_create_u32("rx_mini_max_pending", 0600, dir,
+			   &ns->ethtool.ring.rx_mini_max_pending);
+	debugfs_create_u32("tx_max_pending", 0600, dir,
+			   &ns->ethtool.ring.tx_max_pending);
+}
+
+void nsim_ethtool_fini(struct netdevsim *ns)
+{
+	debugfs_remove(ns->ethtool_ddir);
+}