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/fb/pvr2fb.rst | 66 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 Documentation/fb/pvr2fb.rst (limited to 'Documentation/fb/pvr2fb.rst') diff --git a/Documentation/fb/pvr2fb.rst b/Documentation/fb/pvr2fb.rst new file mode 100644 index 000000000..315ce085a --- /dev/null +++ b/Documentation/fb/pvr2fb.rst @@ -0,0 +1,66 @@ +=============================================== +pvr2fb - PowerVR 2 graphics frame buffer driver +=============================================== + +This is a driver for PowerVR 2 based graphics frame buffers, such as the +one found in the Dreamcast. + +Advantages: + + * It provides a nice large console (128 cols + 48 lines with 1024x768) + without using tiny, unreadable fonts (NOT on the Dreamcast) + * You can run XF86_FBDev on top of /dev/fb0 + * Most important: boot logo :-) + +Disadvantages: + + * Driver is largely untested on non-Dreamcast systems. + +Configuration +============= + +You can pass kernel command line options to pvr2fb with +`video=pvr2fb:option1,option2:value2,option3` (multiple options should be +separated by comma, values are separated from options by `:`). + +Accepted options: + +========== ================================================================== +font:X default font to use. All fonts are supported, including the + SUN12x22 font which is very nice at high resolutions. + + +mode:X default video mode with format [xres]x[yres]-@ + The following video modes are supported: + 640x640-16@60, 640x480-24@60, 640x480-32@60. The Dreamcast + defaults to 640x480-16@60. At the time of writing the + 24bpp and 32bpp modes function poorly. Work to fix that is + ongoing + + Note: the 640x240 mode is currently broken, and should not be + used for any reason. It is only mentioned here as a reference. + +inverse invert colors on screen (for LCD displays) + +nomtrr disables write combining on frame buffer. This slows down driver + but there is reported minor incompatibility between GUS DMA and + XFree under high loads if write combining is enabled (sound + dropouts). MTRR is enabled by default on systems that have it + configured and that support it. + +cable:X cable type. This can be any of the following: vga, rgb, and + composite. If none is specified, we guess. + +output:X output type. This can be any of the following: pal, ntsc, and + vga. If none is specified, we guess. +========== ================================================================== + +X11 +=== + +XF86_FBDev has been shown to work on the Dreamcast in the past - though not yet +on any 2.6 series kernel. + +Paul Mundt + +Updated by Adrian McMenamin -- cgit v1.3.1