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, 56 insertions, 0 deletions

diff --git a/drivers/spi/internals.h b/drivers/spi/internals.h
new file mode 100644
index 000000000..c56c190b0
--- /dev/null
+++ b/drivers/spi/internals.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2018 Exceet Electronics GmbH
+ * Copyright (C) 2018 Bootlin
+ *
+ * Author: Boris Brezillon <boris.brezillon@bootlin.com>
+ *
+ * Helpers needed by the SPI core and its tests. Should not be used outside
+ * drivers/spi/.
+ */
+
+#ifndef __LINUX_SPI_INTERNALS_H
+#define __LINUX_SPI_INTERNALS_H
+
+#include <linux/device.h>
+#include <linux/dma-direction.h>
+#include <linux/scatterlist.h>
+#include <linux/spi/spi.h>
+
+void spi_flush_queue(struct spi_controller *ctrl);
+
+#ifdef CONFIG_HAS_DMA
+#if IS_ENABLED(CONFIG_KUNIT)
+int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg);
+int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg);
+#endif
+
+int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
+		struct sg_table *sgt, void *buf, size_t len,
+		enum dma_data_direction dir);
+void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
+		   struct sg_table *sgt, enum dma_data_direction dir);
+#else /* !CONFIG_HAS_DMA */
+static inline int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
+			      struct sg_table *sgt, void *buf, size_t len,
+			      enum dma_data_direction dir)
+{
+	return -EINVAL;
+}
+
+static inline void spi_unmap_buf(struct spi_controller *ctlr,
+				 struct device *dev, struct sg_table *sgt,
+				 enum dma_data_direction dir)
+{
+}
+#endif /* CONFIG_HAS_DMA */
+
+static inline bool spi_xfer_is_dma_mapped(struct spi_controller *ctlr,
+					  struct spi_device *spi,
+					  struct spi_transfer *xfer)
+{
+	return ctlr->can_dma && ctlr->can_dma(ctlr, spi, xfer) &&
+	       (xfer->tx_sg_mapped || xfer->rx_sg_mapped);
+}
+
+#endif /* __LINUX_SPI_INTERNALS_H */