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, 86 insertions, 0 deletions

diff --git a/fs/isofs/util.c b/fs/isofs/util.c
new file mode 100644
index 000000000..42f479da0
--- /dev/null
+++ b/fs/isofs/util.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/isofs/util.c
+ */
+
+#include <linux/time.h>
+#include "isofs.h"
+
+/* 
+ * We have to convert from a MM/DD/YY format to the Unix ctime format.
+ * We have to take into account leap years and all of that good stuff.
+ * Unfortunately, the kernel does not have the information on hand to
+ * take into account daylight savings time, but it shouldn't matter.
+ * The time stored should be localtime (with or without DST in effect),
+ * and the timezone offset should hold the offset required to get back
+ * to GMT.  Thus  we should always be correct.
+ */
+
+struct timespec64 iso_date(u8 *p, int flags)
+{
+	int year, month, day, hour, minute, second, tz;
+	struct timespec64 ts;
+
+	if (flags & ISO_DATE_LONG_FORM) {
+		year = (p[0] - '0') * 1000 +
+		       (p[1] - '0') * 100 +
+		       (p[2] - '0') * 10 +
+		       (p[3] - '0') - 1900;
+		month = ((p[4] - '0') * 10 + (p[5] - '0'));
+		day = ((p[6] - '0') * 10 + (p[7] - '0'));
+		hour = ((p[8] - '0') * 10 + (p[9] - '0'));
+		minute = ((p[10] - '0') * 10 + (p[11] - '0'));
+		second = ((p[12] - '0') * 10 + (p[13] - '0'));
+		ts.tv_nsec = ((p[14] - '0') * 10 + (p[15] - '0')) * 10000000;
+		tz = p[16];
+	} else {
+		year = p[0];
+		month = p[1];
+		day = p[2];
+		hour = p[3];
+		minute = p[4];
+		second = p[5];
+		ts.tv_nsec = 0;
+		/* High sierra has no time zone */
+		tz = flags & ISO_DATE_HIGH_SIERRA ? 0 : p[6];
+	}
+
+	if (year < 0) {
+		ts.tv_sec = 0;
+	} else {
+		ts.tv_sec = mktime64(year+1900, month, day, hour, minute, second);
+
+		/* sign extend */
+		if (tz & 0x80)
+			tz |= (-1 << 8);
+
+		/* 
+		 * The timezone offset is unreliable on some disks,
+		 * so we make a sanity check.  In no case is it ever
+		 * more than 13 hours from GMT, which is 52*15min.
+		 * The time is always stored in localtime with the
+		 * timezone offset being what get added to GMT to
+		 * get to localtime.  Thus we need to subtract the offset
+		 * to get to true GMT, which is what we store the time
+		 * as internally.  On the local system, the user may set
+		 * their timezone any way they wish, of course, so GMT
+		 * gets converted back to localtime on the receiving
+		 * system.
+		 *
+		 * NOTE: mkisofs in versions prior to mkisofs-1.10 had
+		 * the sign wrong on the timezone offset.  This has now
+		 * been corrected there too, but if you are getting screwy
+		 * results this may be the explanation.  If enough people
+		 * complain, a user configuration option could be added
+		 * to add the timezone offset in with the wrong sign
+		 * for 'compatibility' with older discs, but I cannot see how
+		 * it will matter that much.
+		 *
+		 * Thanks to kuhlmav@elec.canterbury.ac.nz (Volker Kuhlmann)
+		 * for pointing out the sign error.
+		 */
+		if (-52 <= tz && tz <= 52)
+			ts.tv_sec -= tz * 15 * 60;
+	}
+	return ts;
+}