Re: [PATCH v5 01/11] tracing/user_events: Split header into uapi and kernel

Beau Belgrave
2022-12-05T22:30:28Z

On Mon, Dec 05, 2022 at 04:13:28PM -0500, Mathieu Desnoyers wrote:
> On 2022-12-05 16:00, Beau Belgrave wrote:
> > The UAPI parts need to be split out from the kernel parts of user_events
> > now that other parts of the kernel will reference it. Do so by moving
> > the existing include/linux/user_events.h into
> > include/uapi/linux/user_events.h.
> >
> > Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
> > ---
> > include/linux/user_events.h | 52 +++++---------------------------
> > include/uapi/linux/user_events.h | 48 +++++++++++++++++++++++++++++
> > kernel/trace/trace_events_user.c | 5 ---
> > 3 files changed, 56 insertions(+), 49 deletions(-)
> > create mode 100644 include/uapi/linux/user_events.h
> >
> > diff --git a/include/linux/user_events.h b/include/linux/user_events.h
> > index 592a3fbed98e..036b360f3d97 100644
> > --- a/include/linux/user_events.h
> > +++ b/include/linux/user_events.h
> > @@ -1,54 +1,18 @@
> > -/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > /*
> > - * Copyright (c) 2021, Microsoft Corporation.
> > + * Copyright (c) 2022, Microsoft Corporation.
> > *
> > * Authors:
> > * Beau Belgrave <beaub@linux.microsoft.com>
> > */
> > -#ifndef _UAPI_LINUX_USER_EVENTS_H
> > -#define _UAPI_LINUX_USER_EVENTS_H
> > -#include <linux/types.h>
> > -#include <linux/ioctl.h>
> > +#ifndef _LINUX_USER_EVENTS_H
> > +#define _LINUX_USER_EVENTS_H
> > -#ifdef __KERNEL__
> > -#include <linux/uio.h>
> > +#include <uapi/linux/user_events.h>
> > +
> > +#ifdef CONFIG_USER_EVENTS
> > #else
> > -#include <sys/uio.h>
> > #endif
>
> Not sure why this is left here ?
>
> #ifdef CONFIG_USER_EVENTS
> #else
> #endif
>
> It seems useless at this stage. Perhaps it's meant to show up in a following
> patch ?
>

Yes, it's used in later patches. I can fix this up so it's less odd
here.

Thanks,
-Beau

> [...]
>
> > -
> > -#endif /* _UAPI_LINUX_USER_EVENTS_H */
> > +#endif /* _LINUX_USER_EVENTS_H */
> > diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h
> > new file mode 100644
> > index 000000000000..7700759a7cd9
> > --- /dev/null
> > +++ b/include/uapi/linux/user_events.h
> > @@ -0,0 +1,48 @@
> > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> > +/*
> > + * Copyright (c) 2021-2022, Microsoft Corporation.
> > + *
> > + * Authors:
> > + * Beau Belgrave <beaub@linux.microsoft.com>
> > + */
> > +#ifndef _UAPI_LINUX_USER_EVENTS_H
> > +#define _UAPI_LINUX_USER_EVENTS_H
> > +
> > +#include <linux/types.h>
> > +#include <linux/ioctl.h>
> > +
> > +#define USER_EVENTS_SYSTEM "user_events"
> > +#define USER_EVENTS_PREFIX "u:"
> > +
> > +/* Create dynamic location entry within a 32-bit value */
> > +#define DYN_LOC(offset, size) ((size) << 16 | (offset))
> > +
> > +/*
> > + * Describes an event registration and stores the results of the registration.
> > + * This structure is passed to the DIAG_IOCSREG ioctl, callers at a minimum
> > + * must set the size and name_args before invocation.
> > + */
> > +struct user_reg {
> > +
> > + /* Input: Size of the user_reg structure being used */
> > + __u32 size;
> > +
> > + /* Input: Pointer to string with event name, description and flags */
> > + __u64 name_args;
> > +
> > + /* Output: Bitwise index of the event within the status page */
> > + __u32 status_bit;
> > +
> > + /* Output: Index of the event to use when writing data */
> > + __u32 write_index;
> > +} __attribute__((__packed__));
> > +
> > +#define DIAG_IOC_MAGIC '*'
> > +
> > +/* Requests to register a user_event */
> > +#define DIAG_IOCSREG _IOWR(DIAG_IOC_MAGIC, 0, struct user_reg*)
>
> Coding style: "struct user_reg *" (space before '*').
>

Will do.

> > +
> > +/* Requests to delete a user_event */
> > +#define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char*)
>
> Coding style: space before '*'.
>

Will do.

> I notice the use of plural for "Requests". Are those batched requests, or a
> single request ?
>

It is a single request, I'll change this to just "Request" to make it
clear.

Thanks,
-Beau

> Thanks,
>
> Mathieu
>
> > +
> > +#endif /* _UAPI_LINUX_USER_EVENTS_H */
> > diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
> > index ae78c2d53c8a..890357b48c37 100644
> > --- a/kernel/trace/trace_events_user.c
> > +++ b/kernel/trace/trace_events_user.c
> > @@ -19,12 +19,7 @@
> > #include <linux/tracefs.h>
> > #include <linux/types.h>
> > #include <linux/uaccess.h>
> > -/* Reminder to move to uapi when everything works */
> > -#ifdef CONFIG_COMPILE_TEST
> > #include <linux/user_events.h>
> > -#else
> > -#include <uapi/linux/user_events.h>
> > -#endif
> > #include "trace.h"
> > #include "trace_dynevent.h"
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> https://www.efficios.com