From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- Documentation/filesystems/bfs.rst | 60 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 Documentation/filesystems/bfs.rst (limited to 'Documentation/filesystems/bfs.rst') diff --git a/Documentation/filesystems/bfs.rst b/Documentation/filesystems/bfs.rst new file mode 100644 index 000000000..ce14b9018 --- /dev/null +++ b/Documentation/filesystems/bfs.rst @@ -0,0 +1,60 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================== +BFS Filesystem for Linux +======================== + +The BFS filesystem is used by SCO UnixWare OS for the /stand slice, which +usually contains the kernel image and a few other files required for the +boot process. + +In order to access /stand partition under Linux you obviously need to +know the partition number and the kernel must support UnixWare disk slices +(CONFIG_UNIXWARE_DISKLABEL config option). However BFS support does not +depend on having UnixWare disklabel support because one can also mount +BFS filesystem via loopback:: + + # losetup /dev/loop0 stand.img + # mount -t bfs /dev/loop0 /mnt/stand + +where stand.img is a file containing the image of BFS filesystem. +When you have finished using it and umounted you need to also deallocate +/dev/loop0 device by:: + + # losetup -d /dev/loop0 + +You can simplify mounting by just typing:: + + # mount -t bfs -o loop stand.img /mnt/stand + +this will allocate the first available loopback device (and load loop.o +kernel module if necessary) automatically. If the loopback driver is not +loaded automatically, make sure that you have compiled the module and +that modprobe is functioning. Beware that umount will not deallocate +/dev/loopN device if /etc/mtab file on your system is a symbolic link to +/proc/mounts. You will need to do it manually using "-d" switch of +losetup(8). Read losetup(8) manpage for more info. + +To create the BFS image under UnixWare you need to find out first which +slice contains it. The command prtvtoc(1M) is your friend:: + + # prtvtoc /dev/rdsk/c0b0t0d0s0 + +(assuming your root disk is on target=0, lun=0, bus=0, controller=0). Then you +look for the slice with tag "STAND", which is usually slice 10. With this +information you can use dd(1) to create the BFS image:: + + # umount /stand + # dd if=/dev/rdsk/c0b0t0d0sa of=stand.img bs=512 + +Just in case, you can verify that you have done the right thing by checking +the magic number:: + + # od -Ad -tx4 stand.img | more + +The first 4 bytes should be 0x1badface. + +If you have any patches, questions or suggestions regarding this BFS +implementation please contact the author: + +Tigran Aivazian -- cgit v1.3.1