From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
linux-kernel@vger.kernel.org
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Bjorn Helgaas <bhelgaas@google.com>,
Borislav Petkov <bp@alien8.de>,
"David S. Miller" <davem@davemloft.net>,
edumazet@google.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Josh Triplett <josh@joshtriplett.org>,
keescook@chromium.org, kernel-hardening@lists.openwall.com,
Lai Jiangshan <jiangshanlai@gmail.com>,
Len Brown <lenb@kernel.org>,
linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org,
linux-pm@vger.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
neilb@suse.com, netdev@vger.kernel.org, oleg@redhat.com,
"Paul E. McKenney" <paulmck@linux.ibm.com>,
Pavel Machek <pavel@ucw.cz>,
peterz@infradead.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
rcu@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
Tejun Heo <tj@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>
Subject: Re: [RFC 1/6] rcu: Add support for consolidated-RCU reader checking
Date: Tue, 4 Jun 2019 16:01:00 +0200 [thread overview]
Message-ID: <0ff9e0e3-b9fb-8953-1f76-807102f785ee@rasmusvillemoes.dk> (raw)
In-Reply-To: <20190601222738.6856-2-joel@joelfernandes.org>
On 02/06/2019 00.27, Joel Fernandes (Google) wrote:
> This patch adds support for checking RCU reader sections in list
> traversal macros. Optionally, if the list macro is called under SRCU or
> other lock/mutex protection, then appropriate lockdep expressions can be
> passed to make the checks pass.
>
> Existing list_for_each_entry_rcu() invocations don't need to pass the
> optional fourth argument (cond) unless they are under some non-RCU
> protection and needs to make lockdep check pass.
>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> ---
> include/linux/rculist.h | 40 ++++++++++++++++++++++++++++++++++++----
> include/linux/rcupdate.h | 7 +++++++
> kernel/rcu/update.c | 26 ++++++++++++++++++++++++++
> 3 files changed, 69 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> index e91ec9ddcd30..b641fdd9f1a2 100644
> --- a/include/linux/rculist.h
> +++ b/include/linux/rculist.h
> @@ -40,6 +40,25 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
> */
> #define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next)))
>
> +/*
> + * Check during list traversal that we are within an RCU reader
> + */
> +#define __list_check_rcu() \
> + RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), \
> + "RCU-list traversed in non-reader section!")
> +
> +static inline void __list_check_rcu_cond(int dummy, ...)
> +{
> + va_list ap;
> + int cond;
> +
> + va_start(ap, dummy);
> + cond = va_arg(ap, int);
> + va_end(ap);
> +
> + RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(),
> + "RCU-list traversed in non-reader section!");
> +}
> /*
> * Insert a new entry between two known consecutive entries.
> *
> @@ -338,6 +357,9 @@ static inline void list_splice_tail_init_rcu(struct list_head *list,
> member) : NULL; \
> })
>
> +#define SIXTH_ARG(a1, a2, a3, a4, a5, a6, ...) a6
> +#define COUNT_VARGS(...) SIXTH_ARG(dummy, ## __VA_ARGS__, 4, 3, 2, 1, 0)
> +> /**
> * list_for_each_entry_rcu - iterate over rcu list of given type
> * @pos: the type * to use as a loop cursor.
> @@ -348,9 +370,14 @@ static inline void list_splice_tail_init_rcu(struct list_head *list,
> * the _rcu list-mutation primitives such as list_add_rcu()
> * as long as the traversal is guarded by rcu_read_lock().
> */
> -#define list_for_each_entry_rcu(pos, head, member) \
> - for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
> - &pos->member != (head); \
> +#define list_for_each_entry_rcu(pos, head, member, cond...) \
> + if (COUNT_VARGS(cond) != 0) { \
> + __list_check_rcu_cond(0, ## cond); \
> + } else { \
> + __list_check_rcu(); \
> + } \
> + for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
> + &pos->member != (head); \
> pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
Wouldn't something as simple as
#define __list_check_rcu(dummy, cond, ...) \
RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(), \
"RCU-list traversed in non-reader section!");
for ( ({ __list_check_rcu(junk, ##cond, 0); }), pos = ... )
work just as well (i.e., no need for two list_check_rcu and
list_check_rcu_cond variants)? If there's an optional cond, we use that,
if not, we pick the trailing 0, so !cond disappears and it reduces to
your __list_check_rcu(). Moreover, this ensures the RCU_LOCKDEP_WARN
expansion actually picks up the __LINE__ and __FILE__ where the for loop
is used, and not the __FILE__ and __LINE__ of the static inline function
from the header file. It also makes it a bit more type safe/type generic
(if the cond expression happened to have type long or u64 something
rather odd could happen with the inline vararg function).
Rasmus
next prev parent reply other threads:[~2019-06-04 14:01 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-01 22:27 [RFC 0/6] Harden list_for_each_entry_rcu() and family Joel Fernandes (Google)
2019-06-01 22:27 ` [RFC 1/6] rcu: Add support for consolidated-RCU reader checking Joel Fernandes (Google)
2019-06-03 8:01 ` Peter Zijlstra
2019-06-03 14:18 ` Joel Fernandes
2019-06-03 19:42 ` Joel Fernandes
2019-06-04 10:53 ` Steven Rostedt
2019-06-04 17:48 ` Joel Fernandes
2019-06-04 14:01 ` Rasmus Villemoes [this message]
2019-06-04 23:57 ` Joel Fernandes
2019-06-01 22:27 ` [RFC 2/6] ipv4: add lockdep condition to fix for_each_entry Joel Fernandes (Google)
2019-06-02 7:00 ` Pavel Machek
2019-06-02 12:20 ` Joel Fernandes
2019-06-02 12:24 ` Joel Fernandes
2019-06-03 6:42 ` Pavel Machek
2019-06-03 12:28 ` Joel Fernandes
2019-06-01 22:27 ` [RFC 3/6] driver/core: Convert to use built-in RCU list checking Joel Fernandes (Google)
2019-06-01 22:27 ` [RFC 4/6] workqueue: Convert for_each_wq to use built-in list check Joel Fernandes (Google)
2019-06-05 1:24 ` Daniel Jordan
2019-06-05 13:04 ` Joel Fernandes
2019-06-01 22:27 ` [RFC 5/6] x86/pci: Pass lockdep condition to pcm_mmcfg_list iterator Joel Fernandes (Google)
2019-06-01 22:27 ` [RFC 6/6] acpi: Use built-in RCU list checking for acpi_ioremaps list Joel Fernandes (Google)
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