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, 328 insertions, 0 deletions

diff --git a/net/ethtool/mse.c b/net/ethtool/mse.c
new file mode 100644
index 000000000..e91b74430
--- /dev/null
+++ b/net/ethtool/mse.c
@@ -0,0 +1,328 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/ethtool.h>
+#include <linux/phy.h>
+#include <linux/slab.h>
+
+#include "common.h"
+#include "netlink.h"
+
+/* Channels A-D only; WORST and LINK are exclusive alternatives */
+#define PHY_MSE_CHANNEL_COUNT 4
+
+struct mse_req_info {
+	struct ethnl_req_info base;
+};
+
+struct mse_snapshot_entry {
+	struct phy_mse_snapshot snapshot;
+	int channel;
+};
+
+struct mse_reply_data {
+	struct ethnl_reply_data base;
+	struct phy_mse_capability capability;
+	struct mse_snapshot_entry *snapshots;
+	unsigned int num_snapshots;
+};
+
+static struct mse_reply_data *
+mse_repdata(const struct ethnl_reply_data *reply_base)
+{
+	return container_of(reply_base, struct mse_reply_data, base);
+}
+
+const struct nla_policy ethnl_mse_get_policy[] = {
+	[ETHTOOL_A_MSE_HEADER] = NLA_POLICY_NESTED(ethnl_header_policy_phy),
+};
+
+static int get_snapshot_if_supported(struct phy_device *phydev,
+				     struct mse_reply_data *data,
+				     unsigned int *idx, u32 cap_bit,
+				     enum phy_mse_channel channel)
+{
+	int ret;
+
+	if (data->capability.supported_caps & cap_bit) {
+		ret = phydev->drv->get_mse_snapshot(phydev, channel,
+					&data->snapshots[*idx].snapshot);
+		if (ret)
+			return ret;
+		data->snapshots[*idx].channel = channel;
+		(*idx)++;
+	}
+
+	return 0;
+}
+
+static int mse_get_channels(struct phy_device *phydev,
+			    struct mse_reply_data *data)
+{
+	unsigned int i = 0;
+	int ret;
+
+	if (!data->capability.supported_caps)
+		return 0;
+
+	data->snapshots = kzalloc_objs(*data->snapshots, PHY_MSE_CHANNEL_COUNT);
+	if (!data->snapshots)
+		return -ENOMEM;
+
+	/* Priority 1: Individual channels */
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_A,
+					PHY_MSE_CHANNEL_A);
+	if (ret)
+		return ret;
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_B,
+					PHY_MSE_CHANNEL_B);
+	if (ret)
+		return ret;
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_C,
+					PHY_MSE_CHANNEL_C);
+	if (ret)
+		return ret;
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_D,
+					PHY_MSE_CHANNEL_D);
+	if (ret)
+		return ret;
+
+	/* If any individual channels were found, we are done. */
+	if (i > 0) {
+		data->num_snapshots = i;
+		return 0;
+	}
+
+	/* Priority 2: Worst channel, if no individual channels supported. */
+	ret = get_snapshot_if_supported(phydev, data, &i,
+					PHY_MSE_CAP_WORST_CHANNEL,
+					PHY_MSE_CHANNEL_WORST);
+	if (ret)
+		return ret;
+
+	/* If worst channel was found, we are done. */
+	if (i > 0) {
+		data->num_snapshots = i;
+		return 0;
+	}
+
+	/* Priority 3: Link-wide, if nothing else is supported. */
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_LINK,
+					PHY_MSE_CHANNEL_LINK);
+	if (ret)
+		return ret;
+
+	data->num_snapshots = i;
+	return 0;
+}
+
+static int mse_prepare_data(const struct ethnl_req_info *req_base,
+			    struct ethnl_reply_data *reply_base,
+			    const struct genl_info *info)
+{
+	struct mse_reply_data *data = mse_repdata(reply_base);
+	struct net_device *dev = reply_base->dev;
+	struct phy_device *phydev;
+	int ret;
+
+	phydev = ethnl_req_get_phydev(req_base, info->attrs,
+				      ETHTOOL_A_MSE_HEADER, info->extack);
+	if (IS_ERR(phydev))
+		return PTR_ERR(phydev);
+	if (!phydev)
+		return -EOPNOTSUPP;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret)
+		return ret;
+
+	mutex_lock(&phydev->lock);
+
+	if (!phydev->drv || !phydev->drv->get_mse_capability ||
+	    !phydev->drv->get_mse_snapshot) {
+		ret = -EOPNOTSUPP;
+		goto out_unlock;
+	}
+	if (!phydev->link) {
+		ret = -ENETDOWN;
+		goto out_unlock;
+	}
+
+	ret = phydev->drv->get_mse_capability(phydev, &data->capability);
+	if (ret)
+		goto out_unlock;
+
+	ret = mse_get_channels(phydev, data);
+
+out_unlock:
+	mutex_unlock(&phydev->lock);
+	ethnl_ops_complete(dev);
+	if (ret)
+		kfree(data->snapshots);
+	return ret;
+}
+
+static void mse_cleanup_data(struct ethnl_reply_data *reply_base)
+{
+	struct mse_reply_data *data = mse_repdata(reply_base);
+
+	kfree(data->snapshots);
+}
+
+static int mse_reply_size(const struct ethnl_req_info *req_base,
+			  const struct ethnl_reply_data *reply_base)
+{
+	const struct mse_reply_data *data = mse_repdata(reply_base);
+	size_t len = 0;
+	unsigned int i;
+
+	/* ETHTOOL_A_MSE_CAPABILITIES */
+	len += nla_total_size(0);
+	if (data->capability.supported_caps & PHY_MSE_CAP_AVG)
+		/* ETHTOOL_A_MSE_CAPABILITIES_MAX_AVERAGE_MSE */
+		len += nla_total_size(sizeof(u64));
+	if (data->capability.supported_caps & (PHY_MSE_CAP_PEAK |
+					       PHY_MSE_CAP_WORST_PEAK))
+		/* ETHTOOL_A_MSE_CAPABILITIES_MAX_PEAK_MSE */
+		len += nla_total_size(sizeof(u64));
+	/* ETHTOOL_A_MSE_CAPABILITIES_REFRESH_RATE_PS */
+	len += nla_total_size(sizeof(u64));
+	/* ETHTOOL_A_MSE_CAPABILITIES_NUM_SYMBOLS */
+	len += nla_total_size(sizeof(u64));
+
+	for (i = 0; i < data->num_snapshots; i++) {
+		size_t snapshot_len = 0;
+
+		/* Per-channel nest (e.g., ETHTOOL_A_MSE_CHANNEL_A / _B / _C /
+		 * _D / _WORST_CHANNEL / _LINK)
+		 */
+		snapshot_len += nla_total_size(0);
+
+		if (data->capability.supported_caps & PHY_MSE_CAP_AVG)
+			snapshot_len += nla_total_size(sizeof(u64));
+		if (data->capability.supported_caps & PHY_MSE_CAP_PEAK)
+			snapshot_len += nla_total_size(sizeof(u64));
+		if (data->capability.supported_caps & PHY_MSE_CAP_WORST_PEAK)
+			snapshot_len += nla_total_size(sizeof(u64));
+
+		len += snapshot_len;
+	}
+
+	return len;
+}
+
+static int mse_channel_to_attr(int ch)
+{
+	switch (ch) {
+	case PHY_MSE_CHANNEL_A:
+		return ETHTOOL_A_MSE_CHANNEL_A;
+	case PHY_MSE_CHANNEL_B:
+		return ETHTOOL_A_MSE_CHANNEL_B;
+	case PHY_MSE_CHANNEL_C:
+		return ETHTOOL_A_MSE_CHANNEL_C;
+	case PHY_MSE_CHANNEL_D:
+		return ETHTOOL_A_MSE_CHANNEL_D;
+	case PHY_MSE_CHANNEL_WORST:
+		return ETHTOOL_A_MSE_WORST_CHANNEL;
+	case PHY_MSE_CHANNEL_LINK:
+		return ETHTOOL_A_MSE_LINK;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mse_fill_reply(struct sk_buff *skb,
+			  const struct ethnl_req_info *req_base,
+			  const struct ethnl_reply_data *reply_base)
+{
+	const struct mse_reply_data *data = mse_repdata(reply_base);
+	struct nlattr *nest;
+	unsigned int i;
+	int ret;
+
+	nest = nla_nest_start(skb, ETHTOOL_A_MSE_CAPABILITIES);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (data->capability.supported_caps & PHY_MSE_CAP_AVG) {
+		ret = nla_put_uint(skb,
+				   ETHTOOL_A_MSE_CAPABILITIES_MAX_AVERAGE_MSE,
+				   data->capability.max_average_mse);
+		if (ret < 0)
+			goto nla_put_nest_failure;
+	}
+
+	if (data->capability.supported_caps & (PHY_MSE_CAP_PEAK |
+					       PHY_MSE_CAP_WORST_PEAK)) {
+		ret = nla_put_uint(skb, ETHTOOL_A_MSE_CAPABILITIES_MAX_PEAK_MSE,
+				   data->capability.max_peak_mse);
+		if (ret < 0)
+			goto nla_put_nest_failure;
+	}
+
+	ret = nla_put_uint(skb, ETHTOOL_A_MSE_CAPABILITIES_REFRESH_RATE_PS,
+			   data->capability.refresh_rate_ps);
+	if (ret < 0)
+		goto nla_put_nest_failure;
+
+	ret = nla_put_uint(skb, ETHTOOL_A_MSE_CAPABILITIES_NUM_SYMBOLS,
+			   data->capability.num_symbols);
+	if (ret < 0)
+		goto nla_put_nest_failure;
+
+	nla_nest_end(skb, nest);
+
+	for (i = 0; i < data->num_snapshots; i++) {
+		const struct mse_snapshot_entry *s = &data->snapshots[i];
+		int chan_attr;
+
+		chan_attr = mse_channel_to_attr(s->channel);
+		if (chan_attr < 0)
+			return chan_attr;
+
+		nest = nla_nest_start(skb, chan_attr);
+		if (!nest)
+			return -EMSGSIZE;
+
+		if (data->capability.supported_caps & PHY_MSE_CAP_AVG) {
+			ret = nla_put_uint(skb,
+					   ETHTOOL_A_MSE_SNAPSHOT_AVERAGE_MSE,
+					   s->snapshot.average_mse);
+			if (ret)
+				goto nla_put_nest_failure;
+		}
+		if (data->capability.supported_caps & PHY_MSE_CAP_PEAK) {
+			ret = nla_put_uint(skb, ETHTOOL_A_MSE_SNAPSHOT_PEAK_MSE,
+					   s->snapshot.peak_mse);
+			if (ret)
+				goto nla_put_nest_failure;
+		}
+		if (data->capability.supported_caps & PHY_MSE_CAP_WORST_PEAK) {
+			ret = nla_put_uint(skb,
+					   ETHTOOL_A_MSE_SNAPSHOT_WORST_PEAK_MSE,
+					   s->snapshot.worst_peak_mse);
+			if (ret)
+				goto nla_put_nest_failure;
+		}
+
+		nla_nest_end(skb, nest);
+	}
+
+	return 0;
+
+nla_put_nest_failure:
+	nla_nest_cancel(skb, nest);
+	return ret;
+}
+
+const struct ethnl_request_ops ethnl_mse_request_ops = {
+	.request_cmd = ETHTOOL_MSG_MSE_GET,
+	.reply_cmd = ETHTOOL_MSG_MSE_GET_REPLY,
+	.hdr_attr = ETHTOOL_A_MSE_HEADER,
+	.req_info_size = sizeof(struct mse_req_info),
+	.reply_data_size = sizeof(struct mse_reply_data),
+
+	.prepare_data = mse_prepare_data,
+	.cleanup_data = mse_cleanup_data,
+	.reply_size = mse_reply_size,
+	.fill_reply = mse_fill_reply,
+};