tracing: Have memmapped ring buffer use ioctl of "R" range 0x20-2F

To prevent conflicts with other ioctl numbers to allow strace to have an
idea of what is happening, add the range of ioctls for the trace buffer
mapping from _IO("T", 0x1) to the range of "R" 0x20 - 0x2F.

Link: https://lore.kernel.org/linux-trace-kernel/20240630105322.GA17573@altlinux.org/
Link: https://lore.kernel.org/linux-trace-kernel/20240630213626.GA23566@altlinux.org/
Cc: Jonathan Corbet <corbet@lwn.net>
Fixes: cf9f0f7c4c5bb ("tracing: Allow user-space mapping of the ring-buffer")
Link: https://lore.kernel.org/20240702153354.367861db@rorschach.local.home
Reported-by: "Dmitry V. Levin" <ldv@strace.io>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index a141e8e65c5d3a3464f890c6370bcf7cb5c8ac97..9a97030c6c8df8c325e882ffb21743224611ee8b 100644 (file)
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -186,6 +186,7 @@ Code  Seq#    Include File                                           Comments
 'Q'   all    linux/soundcard.h
 'R'   00-1F  linux/random.h                                          conflict!
 'R'   01     linux/rfkill.h                                          conflict!
+'R'   20-2F  linux/trace_mmap.h
 'R'   C0-DF  net/bluetooth/rfcomm.h
 'R'   E0     uapi/linux/fsl_mc.h
 'S'   all    linux/cdrom.h                                           conflict!

diff --git a/include/uapi/linux/trace_mmap.h b/include/uapi/linux/trace_mmap.h
index bd1066754220905b01c5c6fef6893e472d2ddfd9..c102ef35d11e408c2193529e21f5d749e62f81ab 100644 (file)
--- a/include/uapi/linux/trace_mmap.h
+++ b/include/uapi/linux/trace_mmap.h
@@ -43,6 +43,6 @@ struct trace_buffer_meta {
        __u64   Reserved2;
 };
 
-#define TRACE_MMAP_IOCTL_GET_READER            _IO('T', 0x1)
+#define TRACE_MMAP_IOCTL_GET_READER            _IO('R', 0x20)
 
 #endif /* _TRACE_MMAP_H_ */