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, 222 insertions, 0 deletions

diff --git a/net/ethtool/pause.c b/net/ethtool/pause.c
new file mode 100644
index 000000000..ccaec8e87
--- /dev/null
+++ b/net/ethtool/pause.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "common.h"
+#include "netlink.h"
+
+struct pause_req_info {
+	struct ethnl_req_info		base;
+	enum ethtool_mac_stats_src	src;
+};
+
+#define PAUSE_REQINFO(__req_base) \
+	container_of(__req_base, struct pause_req_info, base)
+
+struct pause_reply_data {
+	struct ethnl_reply_data		base;
+	struct ethtool_pauseparam	pauseparam;
+	struct ethtool_pause_stats	pausestat;
+};
+
+#define PAUSE_REPDATA(__reply_base) \
+	container_of(__reply_base, struct pause_reply_data, base)
+
+const struct nla_policy ethnl_pause_get_policy[] = {
+	[ETHTOOL_A_PAUSE_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy_stats),
+	[ETHTOOL_A_PAUSE_STATS_SRC]		=
+		NLA_POLICY_MAX(NLA_U32, ETHTOOL_MAC_STATS_SRC_PMAC),
+};
+
+static int pause_parse_request(struct ethnl_req_info *req_base,
+			       const struct genl_info *info,
+			       struct nlattr **tb,
+			       struct netlink_ext_ack *extack)
+{
+	enum ethtool_mac_stats_src src = ETHTOOL_MAC_STATS_SRC_AGGREGATE;
+	struct pause_req_info *req_info = PAUSE_REQINFO(req_base);
+
+	if (tb[ETHTOOL_A_PAUSE_STATS_SRC]) {
+		if (!(req_base->flags & ETHTOOL_FLAG_STATS)) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "ETHTOOL_FLAG_STATS must be set when requesting a source of stats");
+			return -EINVAL;
+		}
+
+		src = nla_get_u32(tb[ETHTOOL_A_PAUSE_STATS_SRC]);
+	}
+
+	req_info->src = src;
+
+	return 0;
+}
+
+static int pause_prepare_data(const struct ethnl_req_info *req_base,
+			      struct ethnl_reply_data *reply_base,
+			      const struct genl_info *info)
+{
+	const struct pause_req_info *req_info = PAUSE_REQINFO(req_base);
+	struct pause_reply_data *data = PAUSE_REPDATA(reply_base);
+	enum ethtool_mac_stats_src src = req_info->src;
+	struct net_device *dev = reply_base->dev;
+	int ret;
+
+	if (!dev->ethtool_ops->get_pauseparam)
+		return -EOPNOTSUPP;
+
+	ethtool_stats_init((u64 *)&data->pausestat,
+			   sizeof(data->pausestat) / 8);
+	data->pausestat.src = src;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+
+	if ((src == ETHTOOL_MAC_STATS_SRC_EMAC ||
+	     src == ETHTOOL_MAC_STATS_SRC_PMAC) &&
+	    !__ethtool_dev_mm_supported(dev)) {
+		NL_SET_ERR_MSG_MOD(info->extack,
+				   "Device does not support MAC merge layer");
+		ethnl_ops_complete(dev);
+		return -EOPNOTSUPP;
+	}
+
+	dev->ethtool_ops->get_pauseparam(dev, &data->pauseparam);
+	if (req_base->flags & ETHTOOL_FLAG_STATS &&
+	    dev->ethtool_ops->get_pause_stats)
+		dev->ethtool_ops->get_pause_stats(dev, &data->pausestat);
+
+	ethnl_ops_complete(dev);
+
+	return 0;
+}
+
+static int pause_reply_size(const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	int n = nla_total_size(sizeof(u8)) +	/* _PAUSE_AUTONEG */
+		nla_total_size(sizeof(u8)) +	/* _PAUSE_RX */
+		nla_total_size(sizeof(u8));	/* _PAUSE_TX */
+
+	if (req_base->flags & ETHTOOL_FLAG_STATS)
+		n += nla_total_size(0) +	/* _PAUSE_STATS */
+		     nla_total_size(sizeof(u32)) + /* _PAUSE_STATS_SRC */
+		     nla_total_size_64bit(sizeof(u64)) * ETHTOOL_PAUSE_STAT_CNT;
+	return n;
+}
+
+static int ethtool_put_stat(struct sk_buff *skb, u64 val, u16 attrtype,
+			    u16 padtype)
+{
+	if (val == ETHTOOL_STAT_NOT_SET)
+		return 0;
+	if (nla_put_u64_64bit(skb, attrtype, val, padtype))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+static int pause_put_stats(struct sk_buff *skb,
+			   const struct ethtool_pause_stats *pause_stats)
+{
+	const u16 pad = ETHTOOL_A_PAUSE_STAT_PAD;
+	struct nlattr *nest;
+
+	if (nla_put_u32(skb, ETHTOOL_A_PAUSE_STATS_SRC, pause_stats->src))
+		return -EMSGSIZE;
+
+	nest = nla_nest_start(skb, ETHTOOL_A_PAUSE_STATS);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (ethtool_put_stat(skb, pause_stats->tx_pause_frames,
+			     ETHTOOL_A_PAUSE_STAT_TX_FRAMES, pad) ||
+	    ethtool_put_stat(skb, pause_stats->rx_pause_frames,
+			     ETHTOOL_A_PAUSE_STAT_RX_FRAMES, pad) ||
+	    ethtool_put_stat(skb, pause_stats->tx_pause_storm_events,
+			     ETHTOOL_A_PAUSE_STAT_TX_PAUSE_STORM_EVENTS, pad))
+		goto err_cancel;
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+err_cancel:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
+static int pause_fill_reply(struct sk_buff *skb,
+			    const struct ethnl_req_info *req_base,
+			    const struct ethnl_reply_data *reply_base)
+{
+	const struct pause_reply_data *data = PAUSE_REPDATA(reply_base);
+	const struct ethtool_pauseparam *pauseparam = &data->pauseparam;
+
+	if (nla_put_u8(skb, ETHTOOL_A_PAUSE_AUTONEG, !!pauseparam->autoneg) ||
+	    nla_put_u8(skb, ETHTOOL_A_PAUSE_RX, !!pauseparam->rx_pause) ||
+	    nla_put_u8(skb, ETHTOOL_A_PAUSE_TX, !!pauseparam->tx_pause))
+		return -EMSGSIZE;
+
+	if (req_base->flags & ETHTOOL_FLAG_STATS &&
+	    pause_put_stats(skb, &data->pausestat))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+/* PAUSE_SET */
+
+const struct nla_policy ethnl_pause_set_policy[] = {
+	[ETHTOOL_A_PAUSE_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+	[ETHTOOL_A_PAUSE_AUTONEG]		= { .type = NLA_U8 },
+	[ETHTOOL_A_PAUSE_RX]			= { .type = NLA_U8 },
+	[ETHTOOL_A_PAUSE_TX]			= { .type = NLA_U8 },
+	[ETHTOOL_A_PAUSE_STATS_SRC]		= { .type = NLA_REJECT },
+};
+
+static int
+ethnl_set_pause_validate(struct ethnl_req_info *req_info,
+			 struct genl_info *info)
+{
+	const struct ethtool_ops *ops = req_info->dev->ethtool_ops;
+
+	return ops->get_pauseparam && ops->set_pauseparam ? 1 : -EOPNOTSUPP;
+}
+
+static int
+ethnl_set_pause(struct ethnl_req_info *req_info, struct genl_info *info)
+{
+	struct net_device *dev = req_info->dev;
+	struct ethtool_pauseparam params = {};
+	struct nlattr **tb = info->attrs;
+	bool mod = false;
+	int ret;
+
+	dev->ethtool_ops->get_pauseparam(dev, &params);
+
+	ethnl_update_bool32(&params.autoneg, tb[ETHTOOL_A_PAUSE_AUTONEG], &mod);
+	ethnl_update_bool32(&params.rx_pause, tb[ETHTOOL_A_PAUSE_RX], &mod);
+	ethnl_update_bool32(&params.tx_pause, tb[ETHTOOL_A_PAUSE_TX], &mod);
+	if (!mod)
+		return 0;
+
+	ret = dev->ethtool_ops->set_pauseparam(dev, &params);
+	return ret < 0 ? ret : 1;
+}
+
+const struct ethnl_request_ops ethnl_pause_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_PAUSE_GET,
+	.reply_cmd		= ETHTOOL_MSG_PAUSE_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_PAUSE_HEADER,
+	.req_info_size		= sizeof(struct pause_req_info),
+	.reply_data_size	= sizeof(struct pause_reply_data),
+
+	.parse_request		= pause_parse_request,
+	.prepare_data		= pause_prepare_data,
+	.reply_size		= pause_reply_size,
+	.fill_reply		= pause_fill_reply,
+
+	.set_validate		= ethnl_set_pause_validate,
+	.set			= ethnl_set_pause,
+	.set_ntf_cmd		= ETHTOOL_MSG_PAUSE_NTF,
+};