On 2024-07-02 11:18, Steven Rostedt wrote:
On Tue, 2 Jul 2024 10:36:03 -0400
Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
I can send a patch this week to update it. Or feel free to send a patch
yourself.
You need to reserve an unused ioctl Code and Seq# range within:
Documentation/userspace-api/ioctl/ioctl-number.rst
Ug, it's been so long, I completely forgot about that file.
Thanks for catching this.
Otherwise this duplicate will confuse all system call instrumentation
tooling.
Agreed, what if we did this then:
-- Steve
diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index a141e8e65c5d..9a97030c6c8d 100644
--- 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 bd1066754220..c102ef35d11e 100644
--- 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)
Note that user events also has this issue: the ioctl is not reserved in
the ioctl-number.rst list. See include/uapi/linux/user_events.h:
#define DIAG_IOC_MAGIC '*'
/* Request to register a user_event */
#define DIAG_IOCSREG _IOWR(DIAG_IOC_MAGIC, 0, struct user_reg *)
/* Request to delete a user_event */
#define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char *)
/* Requests to unregister a user_event */
#define DIAG_IOCSUNREG _IOW(DIAG_IOC_MAGIC, 2, struct user_unreg*)
Where '*' maps to Code 0x2A. Looking at the list I don't see any
conflicts there, but we should definitely add it.
If we use '*' for user events already, perhaps we'd want to consider
using the same range for the ring buffer ioctls ? Arguably one is
about instrumentation and the other is about ring buffer interaction
(data transport), but those are both related to tracing.
Thanks,
Mathieu
#endif /* _TRACE_MMAP_H_ */
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
