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Date:   Mon, 5 Dec 2022 14:30:18 -0800
From:   Beau Belgrave <beaub@linux.microsoft.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc:     rostedt@goodmis.org, mhiramat@kernel.org,
        dcook@linux.microsoft.com, alanau@linux.microsoft.com,
        brauner@kernel.org, akpm@linux-foundation.org,
        linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 01/11] tracing/user_events: Split header into uapi and
 kernel
Message-ID: <20221205223018.GC2270@kbox>
References: <20221205210017.23440-1-beaub@linux.microsoft.com>
 <20221205210017.23440-2-beaub@linux.microsoft.com>
 <27f02c53-e837-67a1-fb59-570f2780fde0@efficios.com>
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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