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, 85 insertions, 0 deletions

diff --git a/block/partitions/sgi.c b/block/partitions/sgi.c
new file mode 100644
index 000000000..2383ca63c
--- /dev/null
+++ b/block/partitions/sgi.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  fs/partitions/sgi.c
+ *
+ *  Code extracted from drivers/block/genhd.c
+ */
+
+#include "check.h"
+
+#define SGI_LABEL_MAGIC 0x0be5a941
+
+enum {
+	LINUX_RAID_PARTITION = 0xfd,	/* autodetect RAID partition */
+};
+
+struct sgi_disklabel {
+	__be32 magic_mushroom;		/* Big fat spliff... */
+	__be16 root_part_num;		/* Root partition number */
+	__be16 swap_part_num;		/* Swap partition number */
+	s8 boot_file[16];		/* Name of boot file for ARCS */
+	u8 _unused0[48];		/* Device parameter useless crapola.. */
+	struct sgi_volume {
+		s8 name[8];		/* Name of volume */
+		__be32 block_num;		/* Logical block number */
+		__be32 num_bytes;		/* How big, in bytes */
+	} volume[15];
+	struct sgi_partition {
+		__be32 num_blocks;		/* Size in logical blocks */
+		__be32 first_block;	/* First logical block */
+		__be32 type;		/* Type of this partition */
+	} partitions[16];
+	__be32 csum;			/* Disk label checksum */
+	__be32 _unused1;			/* Padding */
+};
+
+int sgi_partition(struct parsed_partitions *state)
+{
+	int i, csum;
+	__be32 magic;
+	int slot = 1;
+	unsigned int start, blocks;
+	__be32 *ui, cs;
+	Sector sect;
+	struct sgi_disklabel *label;
+	struct sgi_partition *p;
+
+	label = read_part_sector(state, 0, &sect);
+	if (!label)
+		return -1;
+	p = &label->partitions[0];
+	magic = label->magic_mushroom;
+	if(be32_to_cpu(magic) != SGI_LABEL_MAGIC) {
+		put_dev_sector(sect);
+		return 0;
+	}
+	ui = ((__be32 *) (label + 1)) - 1;
+	for(csum = 0; ui >= ((__be32 *) label);) {
+		cs = *ui--;
+		csum += be32_to_cpu(cs);
+	}
+	if(csum) {
+		printk(KERN_WARNING "Dev %s SGI disklabel: csum bad, label corrupted\n",
+		       state->disk->disk_name);
+		put_dev_sector(sect);
+		return 0;
+	}
+	/* All SGI disk labels have 16 partitions, disks under Linux only
+	 * have 15 minor's.  Luckily there are always a few zero length
+	 * partitions which we don't care about so we never overflow the
+	 * current_minor.
+	 */
+	for(i = 0; i < 16; i++, p++) {
+		blocks = be32_to_cpu(p->num_blocks);
+		start  = be32_to_cpu(p->first_block);
+		if (blocks) {
+			put_partition(state, slot, start, blocks);
+			if (be32_to_cpu(p->type) == LINUX_RAID_PARTITION)
+				state->parts[slot].flags = ADDPART_FLAG_RAID;
+		}
+		slot++;
+	}
+	seq_buf_puts(&state->pp_buf, "\n");
+	put_dev_sector(sect);
+	return 1;
+}