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, 194 insertions, 0 deletions

diff --git a/net/ethtool/phy.c b/net/ethtool/phy.c
new file mode 100644
index 000000000..018b0412b
--- /dev/null
+++ b/net/ethtool/phy.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Bootlin
+ *
+ */
+#include <linux/phy.h>
+#include <linux/phy_link_topology.h>
+#include <linux/sfp.h>
+#include <net/netdev_lock.h>
+
+#include "common.h"
+#include "netlink.h"
+
+struct phy_req_info {
+	struct ethnl_req_info base;
+};
+
+struct phy_reply_data {
+	struct ethnl_reply_data	base;
+	u32 phyindex;
+	char *drvname;
+	char *name;
+	unsigned int upstream_type;
+	char *upstream_sfp_name;
+	unsigned int upstream_index;
+	char *downstream_sfp_name;
+};
+
+#define PHY_REPDATA(__reply_base) \
+	container_of(__reply_base, struct phy_reply_data, base)
+
+const struct nla_policy ethnl_phy_get_policy[ETHTOOL_A_PHY_HEADER + 1] = {
+	[ETHTOOL_A_PHY_HEADER] = NLA_POLICY_NESTED(ethnl_header_policy),
+};
+
+static int phy_reply_size(const struct ethnl_req_info *req_info,
+			  const struct ethnl_reply_data *reply_data)
+{
+	struct phy_reply_data *rep_data = PHY_REPDATA(reply_data);
+	size_t size = 0;
+
+	/* ETHTOOL_A_PHY_INDEX */
+	size += nla_total_size(sizeof(u32));
+
+	/* ETHTOOL_A_DRVNAME */
+	if (rep_data->drvname)
+		size += nla_total_size(strlen(rep_data->drvname) + 1);
+
+	/* ETHTOOL_A_NAME */
+	size += nla_total_size(strlen(rep_data->name) + 1);
+
+	/* ETHTOOL_A_PHY_UPSTREAM_TYPE */
+	size += nla_total_size(sizeof(u32));
+
+	/* ETHTOOL_A_PHY_UPSTREAM_SFP_NAME */
+	if (rep_data->upstream_sfp_name)
+		size += nla_total_size(strlen(rep_data->upstream_sfp_name) + 1);
+
+	/* ETHTOOL_A_PHY_UPSTREAM_INDEX */
+	if (rep_data->upstream_index)
+		size += nla_total_size(sizeof(u32));
+
+	/* ETHTOOL_A_PHY_DOWNSTREAM_SFP_NAME */
+	if (rep_data->downstream_sfp_name)
+		size += nla_total_size(strlen(rep_data->downstream_sfp_name) + 1);
+
+	return size;
+}
+
+static int phy_prepare_data(const struct ethnl_req_info *req_info,
+			    struct ethnl_reply_data *reply_data,
+			    const struct genl_info *info)
+{
+	struct phy_link_topology *topo = reply_data->dev->link_topo;
+	struct phy_reply_data *rep_data = PHY_REPDATA(reply_data);
+	struct nlattr **tb = info->attrs;
+	struct phy_device_node *pdn;
+	struct phy_device *phydev;
+	int ret;
+
+	phydev = ethnl_req_get_phydev(req_info, tb, ETHTOOL_A_PHY_HEADER,
+				      info->extack);
+	if (IS_ERR_OR_NULL(phydev))
+		return -EOPNOTSUPP;
+
+	pdn = xa_load(&topo->phys, phydev->phyindex);
+	if (!pdn)
+		return -EOPNOTSUPP;
+
+	rep_data->phyindex = phydev->phyindex;
+
+	rep_data->name = kstrdup(dev_name(&phydev->mdio.dev), GFP_KERNEL);
+	if (!rep_data->name)
+		return -ENOMEM;
+
+	if (phydev->drv) {
+		rep_data->drvname = kstrdup(phydev->drv->name, GFP_KERNEL);
+		if (!rep_data->drvname) {
+			ret = -ENOMEM;
+			goto err_free_name;
+		}
+	}
+
+	rep_data->upstream_type = pdn->upstream_type;
+
+	if (pdn->upstream_type == PHY_UPSTREAM_PHY) {
+		struct phy_device *upstream = pdn->upstream.phydev;
+		rep_data->upstream_index = upstream->phyindex;
+	}
+
+	if (pdn->parent_sfp_bus) {
+		rep_data->upstream_sfp_name = kstrdup(sfp_get_name(pdn->parent_sfp_bus),
+						      GFP_KERNEL);
+		if (!rep_data->upstream_sfp_name) {
+			ret = -ENOMEM;
+			goto err_free_drvname;
+		}
+	}
+
+	if (phydev->sfp_bus) {
+		rep_data->downstream_sfp_name = kstrdup(sfp_get_name(phydev->sfp_bus),
+							GFP_KERNEL);
+		if (!rep_data->downstream_sfp_name) {
+			ret = -ENOMEM;
+			goto err_free_upstream_sfp;
+		}
+	}
+
+	return 0;
+
+err_free_upstream_sfp:
+	kfree(rep_data->upstream_sfp_name);
+err_free_drvname:
+	kfree(rep_data->drvname);
+err_free_name:
+	kfree(rep_data->name);
+	return ret;
+}
+
+static int phy_fill_reply(struct sk_buff *skb,
+			  const struct ethnl_req_info *req_info,
+			  const struct ethnl_reply_data *reply_data)
+{
+	struct phy_reply_data *rep_data = PHY_REPDATA(reply_data);
+
+	if (nla_put_u32(skb, ETHTOOL_A_PHY_INDEX, rep_data->phyindex) ||
+	    nla_put_string(skb, ETHTOOL_A_PHY_NAME, rep_data->name) ||
+	    nla_put_u32(skb, ETHTOOL_A_PHY_UPSTREAM_TYPE, rep_data->upstream_type))
+		return -EMSGSIZE;
+
+	if (rep_data->drvname &&
+	    nla_put_string(skb, ETHTOOL_A_PHY_DRVNAME, rep_data->drvname))
+		return -EMSGSIZE;
+
+	if (rep_data->upstream_index &&
+	    nla_put_u32(skb, ETHTOOL_A_PHY_UPSTREAM_INDEX,
+			rep_data->upstream_index))
+		return -EMSGSIZE;
+
+	if (rep_data->upstream_sfp_name &&
+	    nla_put_string(skb, ETHTOOL_A_PHY_UPSTREAM_SFP_NAME,
+			   rep_data->upstream_sfp_name))
+		return -EMSGSIZE;
+
+	if (rep_data->downstream_sfp_name &&
+	    nla_put_string(skb, ETHTOOL_A_PHY_DOWNSTREAM_SFP_NAME,
+			   rep_data->downstream_sfp_name))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+static void phy_cleanup_data(struct ethnl_reply_data *reply_data)
+{
+	struct phy_reply_data *rep_data = PHY_REPDATA(reply_data);
+
+	kfree(rep_data->drvname);
+	kfree(rep_data->name);
+	kfree(rep_data->upstream_sfp_name);
+	kfree(rep_data->downstream_sfp_name);
+}
+
+const struct ethnl_request_ops ethnl_phy_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_PHY_GET,
+	.reply_cmd		= ETHTOOL_MSG_PHY_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_PHY_HEADER,
+	.req_info_size		= sizeof(struct phy_req_info),
+	.reply_data_size	= sizeof(struct phy_reply_data),
+
+	.prepare_data		= phy_prepare_data,
+	.reply_size		= phy_reply_size,
+	.fill_reply		= phy_fill_reply,
+	.cleanup_data		= phy_cleanup_data,
+};