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, 160 insertions, 0 deletions

diff --git a/drivers/gpu/host1x/intr.c b/drivers/gpu/host1x/intr.c
new file mode 100644
index 000000000..6a383e0c6
--- /dev/null
+++ b/drivers/gpu/host1x/intr.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Tegra host1x Interrupt Management
+ *
+ * Copyright (c) 2010-2021, NVIDIA Corporation.
+ */
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/overflow.h>
+#include "dev.h"
+#include "fence.h"
+#include "intr.h"
+
+static void host1x_intr_add_fence_to_list(struct host1x_fence_list *list,
+					  struct host1x_syncpt_fence *fence)
+{
+	struct host1x_syncpt_fence *fence_in_list;
+
+	list_for_each_entry_reverse(fence_in_list, &list->list, list) {
+		if ((s32)wrapping_sub(u32, fence_in_list->threshold, fence->threshold) <= 0) {
+			/* Fence in list is before us, we can insert here */
+			list_add(&fence->list, &fence_in_list->list);
+			return;
+		}
+	}
+
+	/* Add as first in list */
+	list_add(&fence->list, &list->list);
+}
+
+static void host1x_intr_update_hw_state(struct host1x *host, struct host1x_syncpt *sp)
+{
+	struct host1x_syncpt_fence *fence;
+
+	if (!list_empty(&sp->fences.list)) {
+		fence = list_first_entry(&sp->fences.list, struct host1x_syncpt_fence, list);
+
+		host1x_hw_intr_set_syncpt_threshold(host, sp->id, fence->threshold);
+		host1x_hw_intr_enable_syncpt_intr(host, sp->id);
+	} else {
+		host1x_hw_intr_disable_syncpt_intr(host, sp->id);
+	}
+}
+
+void host1x_intr_add_fence_locked(struct host1x *host, struct host1x_syncpt_fence *fence)
+{
+	struct host1x_fence_list *fence_list = &fence->sp->fences;
+
+	INIT_LIST_HEAD(&fence->list);
+
+	host1x_intr_add_fence_to_list(fence_list, fence);
+	host1x_intr_update_hw_state(host, fence->sp);
+}
+
+bool host1x_intr_remove_fence(struct host1x *host, struct host1x_syncpt_fence *fence)
+{
+	struct host1x_fence_list *fence_list = &fence->sp->fences;
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&fence_list->lock, irqflags);
+
+	if (list_empty(&fence->list)) {
+		spin_unlock_irqrestore(&fence_list->lock, irqflags);
+		return false;
+	}
+
+	list_del_init(&fence->list);
+	host1x_intr_update_hw_state(host, fence->sp);
+
+	spin_unlock_irqrestore(&fence_list->lock, irqflags);
+
+	return true;
+}
+
+void host1x_intr_handle_interrupt(struct host1x *host, unsigned int id)
+{
+	struct host1x_syncpt *sp = &host->syncpt[id];
+	struct host1x_syncpt_fence *fence, *tmp;
+	unsigned int value;
+
+	value = host1x_syncpt_load(sp);
+
+	spin_lock(&sp->fences.lock);
+
+	list_for_each_entry_safe(fence, tmp, &sp->fences.list, list) {
+		if ((wrapping_sub(u32, value, fence->threshold) & 0x80000000U) != 0U) {
+			/* Fence is not yet expired, we are done */
+			break;
+		}
+
+		list_del_init(&fence->list);
+		host1x_fence_signal(fence);
+	}
+
+	/*
+	 * Re-enable interrupt if necessary. The ISR already disabled the interrupt,
+	 * so if no fences remain, no update is needed.
+	 */
+	if (!list_empty(&sp->fences.list))
+		host1x_intr_update_hw_state(host, sp);
+
+	spin_unlock(&sp->fences.lock);
+}
+
+int host1x_intr_init(struct host1x *host)
+{
+	struct host1x_intr_irq_data *irq_data;
+	unsigned int id;
+	int i, err;
+
+	for (id = 0; id < host1x_syncpt_nb_pts(host); ++id) {
+		struct host1x_syncpt *syncpt = &host->syncpt[id];
+
+		spin_lock_init(&syncpt->fences.lock);
+		INIT_LIST_HEAD(&syncpt->fences.list);
+	}
+
+	irq_data = devm_kcalloc(host->dev, host->num_syncpt_irqs, sizeof(irq_data[0]), GFP_KERNEL);
+	if (!irq_data)
+		return -ENOMEM;
+
+	host1x_hw_intr_disable_all_syncpt_intrs(host);
+
+	for (i = 0; i < host->num_syncpt_irqs; i++) {
+		irq_data[i].host = host;
+		irq_data[i].offset = i;
+
+		err = devm_request_irq(host->dev, host->syncpt_irqs[i],
+				       host->intr_op->isr, IRQF_SHARED,
+				       "host1x_syncpt", &irq_data[i]);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
+void host1x_intr_deinit(struct host1x *host)
+{
+}
+
+void host1x_intr_start(struct host1x *host)
+{
+	u32 hz = clk_get_rate(host->clk);
+	int err;
+
+	mutex_lock(&host->intr_mutex);
+	err = host1x_hw_intr_init_host_sync(host, DIV_ROUND_UP(hz, 1000000));
+	if (err) {
+		mutex_unlock(&host->intr_mutex);
+		return;
+	}
+	mutex_unlock(&host->intr_mutex);
+}
+
+void host1x_intr_stop(struct host1x *host)
+{
+	host1x_hw_intr_disable_all_syncpt_intrs(host);
+}