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, 244 insertions, 0 deletions

diff --git a/drivers/media/firewire/firedtv-dvb.c b/drivers/media/firewire/firedtv-dvb.c
new file mode 100644
index 000000000..3b7e2f1ec
--- /dev/null
+++ b/drivers/media/firewire/firedtv-dvb.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * FireDTV driver (formerly known as FireSAT)
+ *
+ * Copyright (C) 2004 Andreas Monitzer <andy@monitzer.com>
+ * Copyright (C) 2008 Henrik Kurelid <henrik@kurelid.se>
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+
+#include <media/dmxdev.h>
+#include <media/dvb_demux.h>
+#include <media/dvbdev.h>
+#include <media/dvb_frontend.h>
+
+#include "firedtv.h"
+
+static int alloc_channel(struct firedtv *fdtv)
+{
+	int i;
+
+	for (i = 0; i < 16; i++)
+		if (!__test_and_set_bit(i, &fdtv->channel_active))
+			break;
+	return i;
+}
+
+static void collect_channels(struct firedtv *fdtv, int *pidc, u16 pid[])
+{
+	int i, n;
+
+	for (i = 0, n = 0; i < 16; i++)
+		if (test_bit(i, &fdtv->channel_active))
+			pid[n++] = fdtv->channel_pid[i];
+	*pidc = n;
+}
+
+static inline void dealloc_channel(struct firedtv *fdtv, int i)
+{
+	__clear_bit(i, &fdtv->channel_active);
+}
+
+int fdtv_start_feed(struct dvb_demux_feed *dvbdmxfeed)
+{
+	struct firedtv *fdtv = dvbdmxfeed->demux->priv;
+	int pidc, c, ret;
+	u16 pids[16];
+
+	switch (dvbdmxfeed->type) {
+	case DMX_TYPE_TS:
+	case DMX_TYPE_SEC:
+		break;
+	default:
+		dev_err(fdtv->device, "can't start dmx feed: invalid type %u\n",
+			dvbdmxfeed->type);
+		return -EINVAL;
+	}
+
+	if (mutex_lock_interruptible(&fdtv->demux_mutex))
+		return -EINTR;
+
+	if (dvbdmxfeed->type == DMX_TYPE_TS) {
+		switch (dvbdmxfeed->pes_type) {
+		case DMX_PES_VIDEO:
+		case DMX_PES_AUDIO:
+		case DMX_PES_TELETEXT:
+		case DMX_PES_PCR:
+		case DMX_PES_OTHER:
+			c = alloc_channel(fdtv);
+			break;
+		default:
+			dev_err(fdtv->device,
+				"can't start dmx feed: invalid pes type %u\n",
+				dvbdmxfeed->pes_type);
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		c = alloc_channel(fdtv);
+	}
+
+	if (c > 15) {
+		dev_err(fdtv->device, "can't start dmx feed: busy\n");
+		ret = -EBUSY;
+		goto out;
+	}
+
+	dvbdmxfeed->priv = (typeof(dvbdmxfeed->priv))(unsigned long)c;
+	fdtv->channel_pid[c] = dvbdmxfeed->pid;
+	collect_channels(fdtv, &pidc, pids);
+
+	if (dvbdmxfeed->pid == 8192) {
+		ret = avc_tuner_get_ts(fdtv);
+		if (ret) {
+			dealloc_channel(fdtv, c);
+			dev_err(fdtv->device, "can't get TS\n");
+			goto out;
+		}
+	} else {
+		ret = avc_tuner_set_pids(fdtv, pidc, pids);
+		if (ret) {
+			dealloc_channel(fdtv, c);
+			dev_err(fdtv->device, "can't set PIDs\n");
+			goto out;
+		}
+	}
+out:
+	mutex_unlock(&fdtv->demux_mutex);
+
+	return ret;
+}
+
+int fdtv_stop_feed(struct dvb_demux_feed *dvbdmxfeed)
+{
+	struct dvb_demux *demux = dvbdmxfeed->demux;
+	struct firedtv *fdtv = demux->priv;
+	int pidc, c, ret;
+	u16 pids[16];
+
+	if (dvbdmxfeed->type == DMX_TYPE_TS &&
+	    !((dvbdmxfeed->ts_type & TS_PACKET) &&
+	      (demux->dmx.frontend->source != DMX_MEMORY_FE))) {
+
+		if (dvbdmxfeed->ts_type & TS_DECODER) {
+			if (dvbdmxfeed->pes_type >= DMX_PES_OTHER ||
+			    !demux->pesfilter[dvbdmxfeed->pes_type])
+				return -EINVAL;
+
+			demux->pids[dvbdmxfeed->pes_type] |= 0x8000;
+			demux->pesfilter[dvbdmxfeed->pes_type] = NULL;
+		}
+
+		if (!(dvbdmxfeed->ts_type & TS_DECODER &&
+		      dvbdmxfeed->pes_type < DMX_PES_OTHER))
+			return 0;
+	}
+
+	if (mutex_lock_interruptible(&fdtv->demux_mutex))
+		return -EINTR;
+
+	c = (unsigned long)dvbdmxfeed->priv;
+	dealloc_channel(fdtv, c);
+	collect_channels(fdtv, &pidc, pids);
+
+	ret = avc_tuner_set_pids(fdtv, pidc, pids);
+
+	mutex_unlock(&fdtv->demux_mutex);
+
+	return ret;
+}
+
+DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
+
+int fdtv_dvb_register(struct firedtv *fdtv, const char *name)
+{
+	int err;
+
+	err = dvb_register_adapter(&fdtv->adapter, name,
+				   THIS_MODULE, fdtv->device, adapter_nr);
+	if (err < 0)
+		goto fail_log;
+
+	/*DMX_TS_FILTERING | DMX_SECTION_FILTERING*/
+	fdtv->demux.dmx.capabilities = 0;
+
+	fdtv->demux.priv	= fdtv;
+	fdtv->demux.filternum	= 16;
+	fdtv->demux.feednum	= 16;
+	fdtv->demux.start_feed	= fdtv_start_feed;
+	fdtv->demux.stop_feed	= fdtv_stop_feed;
+	fdtv->demux.write_to_decoder = NULL;
+
+	err = dvb_dmx_init(&fdtv->demux);
+	if (err)
+		goto fail_unreg_adapter;
+
+	fdtv->dmxdev.filternum    = 16;
+	fdtv->dmxdev.demux        = &fdtv->demux.dmx;
+	fdtv->dmxdev.capabilities = 0;
+
+	err = dvb_dmxdev_init(&fdtv->dmxdev, &fdtv->adapter);
+	if (err)
+		goto fail_dmx_release;
+
+	fdtv->frontend.source = DMX_FRONTEND_0;
+
+	err = fdtv->demux.dmx.add_frontend(&fdtv->demux.dmx, &fdtv->frontend);
+	if (err)
+		goto fail_dmxdev_release;
+
+	err = fdtv->demux.dmx.connect_frontend(&fdtv->demux.dmx,
+					       &fdtv->frontend);
+	if (err)
+		goto fail_rem_frontend;
+
+	err = dvb_net_init(&fdtv->adapter, &fdtv->dvbnet, &fdtv->demux.dmx);
+	if (err)
+		goto fail_disconnect_frontend;
+
+	fdtv_frontend_init(fdtv, name);
+	err = dvb_register_frontend(&fdtv->adapter, &fdtv->fe);
+	if (err)
+		goto fail_net_release;
+
+	err = fdtv_ca_register(fdtv);
+	if (err)
+		dev_info(fdtv->device,
+			 "Conditional Access Module not enabled\n");
+	return 0;
+
+fail_net_release:
+	dvb_net_release(&fdtv->dvbnet);
+fail_disconnect_frontend:
+	fdtv->demux.dmx.close(&fdtv->demux.dmx);
+fail_rem_frontend:
+	fdtv->demux.dmx.remove_frontend(&fdtv->demux.dmx, &fdtv->frontend);
+fail_dmxdev_release:
+	dvb_dmxdev_release(&fdtv->dmxdev);
+fail_dmx_release:
+	dvb_dmx_release(&fdtv->demux);
+fail_unreg_adapter:
+	dvb_unregister_adapter(&fdtv->adapter);
+fail_log:
+	dev_err(fdtv->device, "DVB initialization failed\n");
+	return err;
+}
+
+void fdtv_dvb_unregister(struct firedtv *fdtv)
+{
+	fdtv_ca_release(fdtv);
+	dvb_unregister_frontend(&fdtv->fe);
+	dvb_net_release(&fdtv->dvbnet);
+	fdtv->demux.dmx.close(&fdtv->demux.dmx);
+	fdtv->demux.dmx.remove_frontend(&fdtv->demux.dmx, &fdtv->frontend);
+	dvb_dmxdev_release(&fdtv->dmxdev);
+	dvb_dmx_release(&fdtv->demux);
+	dvb_unregister_adapter(&fdtv->adapter);
+}