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, 113 insertions, 0 deletions

diff --git a/scripts/bloat-o-meter b/scripts/bloat-o-meter
new file mode 100755
index 000000000..5868a8b11
--- /dev/null
+++ b/scripts/bloat-o-meter
@@ -0,0 +1,113 @@
+#!/usr/bin/env python3
+#
+# Copyright 2004 Matt Mackall <mpm@selenic.com>
+#
+# inspired by perl Bloat-O-Meter (c) 1997 by Andi Kleen
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+import sys, os, re, argparse
+from signal import signal, SIGPIPE, SIG_DFL
+
+signal(SIGPIPE, SIG_DFL)
+
+parser = argparse.ArgumentParser(description="Simple script used to compare the symbol sizes of 2 object files")
+group = parser.add_mutually_exclusive_group()
+group.add_argument('-c', help='categorize output based on symbol type', action='store_true')
+group.add_argument('-d', help='Show delta of Data Section', action='store_true')
+group.add_argument('-t', help='Show delta of text Section', action='store_true')
+parser.add_argument('-p', dest='prefix', help='Arch prefix for the tool being used. Useful in cross build scenarios')
+parser.add_argument('file_old', help='First file to compare')
+parser.add_argument('file_new', help='Second file to compare')
+
+args = parser.parse_args()
+
+re_NUMBER = re.compile(r'\.[0-9]+')
+
+def getsizes(file, format):
+    sym = {}
+    nm = "nm"
+    if args.prefix:
+        nm = "{}nm".format(args.prefix)
+
+    with os.popen("{} --size-sort {}".format(nm, file)) as f:
+        for line in f:
+            if line.startswith("\n") or ":" in line:
+                continue
+            size, type, name = line.split()
+            if type in format:
+                # strip generated symbols
+                if name.startswith("__mod_"): continue
+                if name.startswith("__se_sys"): continue
+                if name.startswith("__se_compat_sys"): continue
+                if name.startswith("__addressable_"): continue
+                if name.startswith("__noinstr_text_start"): continue
+                if name.startswith("_sdata"): continue
+                if name == "linux_banner": continue
+                if name == "vermagic": continue
+                # statics and some other optimizations adds random .NUMBER
+                name = re_NUMBER.sub('', name)
+                sym[name] = sym.get(name, 0) + int(size, 16)
+    return sym
+
+def calc(oldfile, newfile, format):
+    old = getsizes(oldfile, format)
+    new = getsizes(newfile, format)
+    grow, shrink, add, remove, up, down = 0, 0, 0, 0, 0, 0
+    delta, common = [], {}
+    otot, ntot = 0, 0
+
+    for a in old:
+        if a in new:
+            common[a] = 1
+
+    for name in old:
+        otot += old[name]
+        if name not in common:
+            remove += 1
+            down += old[name]
+            delta.append((-old[name], name))
+
+    for name in new:
+        ntot += new[name]
+        if name not in common:
+            add += 1
+            up += new[name]
+            delta.append((new[name], name))
+
+    for name in common:
+        d = new.get(name, 0) - old.get(name, 0)
+        if d>0: grow, up = grow+1, up+d
+        if d<0: shrink, down = shrink+1, down-d
+        delta.append((d, name))
+
+    delta.sort(reverse=True)
+    return grow, shrink, add, remove, up, down, delta, old, new, otot, ntot
+
+def print_result(symboltype, symbolformat):
+    grow, shrink, add, remove, up, down, delta, old, new, otot, ntot = \
+    calc(args.file_old, args.file_new, symbolformat)
+
+    print("add/remove: %s/%s grow/shrink: %s/%s up/down: %s/%s (%s)" % \
+          (add, remove, grow, shrink, up, -down, up-down))
+    print("%-40s %7s %7s %+7s" % (symboltype, "old", "new", "delta"))
+    for d, n in delta:
+        if d: print("%-40s %7s %7s %+7d" % (n, old.get(n,"-"), new.get(n,"-"), d))
+
+    if otot:
+        percent = (ntot - otot) * 100.0 / otot
+    else:
+        percent = 0
+    print("Total: Before=%d, After=%d, chg %+.2f%%" % (otot, ntot, percent))
+
+if args.c:
+    print_result("Function", "tTwW")
+    print_result("Data", "dDbBvV")
+    print_result("RO Data", "rR")
+elif args.d:
+    print_result("Data", "dDbBrRvV")
+elif args.t:
+    print_result("Function", "tTwW")
+else:
+    print_result("Function", "tTdDbBrRvVwW")