linux-kernel - Re: [PATCH v7 2/6] srcu: Add notrace variants of srcu_read

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Date:   Tue, 15 May 2018 16:56:43 -0700
From:   Joel Fernandes <joel.opensrc@...il.com>
To:     Joel Fernandes <joel@...lfernandes.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Boqun Feng <boqun.feng@...il.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Fenguang Wu <fengguang.wu@...el.com>,
        Baohong Liu <baohong.liu@...el.com>,
        Vedang Patel <vedang.patel@...el.com>, kernel-team@...roid.com
Subject: Re: [PATCH v7 2/6] srcu: Add notrace variants of srcu_read_{lock,unlock}

Something is majorly messed up with my SMTP server. Only half of the patches
in this series were sent out and the ones that did go out were random.

I keeping getting this as replies for the one's that didn't go out:
https://support.google.com/mail/answer/6596?visit_id=1-636620224226493206-2884214369&rd=1

And its intermittent too.. I am going to spend a bit of time to figure out
why it happened so it doesn't happen again. Sorry about the noise.

Sigh,

- Joel

On Tue, May 15, 2018 at 3:47 PM Joel Fernandes (Google) <
joel@...lfernandes.org> wrote:

> From: Paul McKenney <paulmck@...ux.vnet.ibm.com>

> This is needed for a future tracepoint patch that uses srcu, and to make
> sure it doesn't call into lockdep.

> tracepoint code already calls notrace variants for rcu_read_lock_sched
> so this patch does the same for srcu which will be used in a later
> patch. Keeps it consistent with rcu-sched.

> [Joel: Added commit message]

> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Peter Zilstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Cc: Tom Zanussi <tom.zanussi@...ux.intel.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Thomas Glexiner <tglx@...utronix.de>
> Cc: Boqun Feng <boqun.feng@...il.com>
> Cc: Paul McKenney <paulmck@...ux.vnet.ibm.com>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Randy Dunlap <rdunlap@...radead.org>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: Fenguang Wu <fengguang.wu@...el.com>
> Cc: Baohong Liu <baohong.liu@...el.com>
> Cc: Vedang Patel <vedang.patel@...el.com>
> Cc: kernel-team@...roid.com
> Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> Signed-off-by: Paul McKenney <paulmck@...ux.vnet.ibm.com>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> ---
>   include/linux/srcu.h | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)

> diff --git a/include/linux/srcu.h b/include/linux/srcu.h
> index 33c1c698df09..2ec618979b20 100644
> --- a/include/linux/srcu.h
> +++ b/include/linux/srcu.h
> @@ -161,6 +161,16 @@ static inline int srcu_read_lock(struct srcu_struct
*sp) __acquires(sp)
>          return retval;
>   }

> +/* Used by tracing, cannot be traced and cannot invoke lockdep. */
> +static inline notrace int
> +srcu_read_lock_notrace(struct srcu_struct *sp) __acquires(sp)
> +{
> +       int retval;
> +
> +       retval = __srcu_read_lock(sp);
> +       return retval;
> +}
> +
>   /**
>    * srcu_read_unlock - unregister a old reader from an SRCU-protected
structure.
>    * @sp: srcu_struct in which to unregister the old reader.
> @@ -175,6 +185,13 @@ static inline void srcu_read_unlock(struct
srcu_struct *sp, int idx)
>          __srcu_read_unlock(sp, idx);
>   }

> +/* Used by tracing, cannot be traced and cannot call lockdep. */
> +static inline notrace void
> +srcu_read_unlock_notrace(struct srcu_struct *sp, int idx) __releases(sp)
> +{
> +       __srcu_read_unlock(sp, idx);
> +}
> +
>   /**
>    * smp_mb__after_srcu_read_unlock - ensure full ordering after
srcu_read_unlock
>    *
> --
> 2.17.0.441.gb46fe60e1d-goog