From: "Paul E. McKenney" <paulmck@linux.ibm.com>
To: Ran Rozenstein <ranro@mellanox.com>
Cc: Joel Fernandes <joel@joelfernandes.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"jiangshanlai@gmail.com" <jiangshanlai@gmail.com>,
"dipankar@in.ibm.com" <dipankar@in.ibm.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"mathieu.desnoyers@efficios.com" <mathieu.desnoyers@efficios.com>,
"josh@joshtriplett.org" <josh@joshtriplett.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"peterz@infradead.org" <peterz@infradead.org>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"dhowells@redhat.com" <dhowells@redhat.com>,
"edumazet@google.com" <edumazet@google.com>,
"fweisbec@gmail.com" <fweisbec@gmail.com>,
"oleg@redhat.com" <oleg@redhat.com>,
Maor Gottlieb <maorg@mellanox.com>,
Tariq Toukan <tariqt@mellanox.com>,
Eran Ben Elisha <eranbe@mellanox.com>,
Leon Romanovsky <leonro@mellanox.com>
Subject: Re: [PATCH tip/core/rcu 02/19] rcu: Defer reporting RCU-preempt quiescent states when disabled
Date: Mon, 26 Nov 2018 11:00:27 -0800 [thread overview]
Message-ID: <20181126190027.GH4170@linux.ibm.com> (raw)
In-Reply-To: <AM4PR0501MB27690D8721451EEE5082E593C5D70@AM4PR0501MB2769.eurprd05.prod.outlook.com>
On Mon, Nov 26, 2018 at 01:55:37PM +0000, Ran Rozenstein wrote:
> >
> > Hearing no objections, here is the updated patch.
> >
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > commit 970cab5d3d206029ed27274a98ea1c3d7e780e53
> > Author: Paul E. McKenney <paulmck@linux.ibm.com>
> > Date: Mon Oct 29 07:36:50 2018 -0700
> >
> > rcu: Avoid signed integer overflow in rcu_preempt_deferred_qs()
> >
> > Subtracting INT_MIN can be interpreted as unconditional signed integer
> > overflow, which according to the C standard is undefined behavior.
> > Therefore, kernel build arguments notwithstanding, it would be good to
> > future-proof the code. This commit therefore substitutes INT_MAX for
> > INT_MIN in order to avoid undefined behavior.
> >
> > While in the neighborhood, this commit also creates some meaningful
> > names
> > for INT_MAX and friends in order to improve readability, as suggested
> > by Joel Fernandes.
> >
> > Reported-by: Ran Rozenstein <ranro@mellanox.com>
> > Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
> >
> > squash! rcu: Avoid signed integer overflow in rcu_preempt_deferred_qs()
> >
> > While in the neighborhood, use macros to give meaningful names.
> >
> > Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
>
> Hi,
>
> What is the acceptance status of this patch?
It is queued in -rcu. If no problems arise beforehand, I intend to submit
it as part of a pull request into -tip, which (again if no problems arise)
be pulled into mainline during the next merge window.
Oddly enough, a couple of weeks ago the C++ Standards Committee voted
in a proposal for C++20 removing undefined behavior for signed integer
overflow. This is C++ rather than C, and C must support additional
hardware that wouldn't much like forcing twos complement for signed
integer overflow. But still... ;-)
Thanx, Paul
next prev parent reply other threads:[~2018-11-26 19:00 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 22:20 [PATCH tip/core/rcu 0/19] RCU flavor-consolidation changes for v4.20/v5.0 Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 01/19] rcu: Refactor rcu_{nmi,irq}_{enter,exit}() Paul E. McKenney
2018-08-30 18:10 ` Steven Rostedt
2018-08-30 23:02 ` Paul E. McKenney
2018-08-31 2:25 ` Byungchul Park
2018-08-29 22:20 ` [PATCH tip/core/rcu 02/19] rcu: Defer reporting RCU-preempt quiescent states when disabled Paul E. McKenney
2018-10-29 11:24 ` Ran Rozenstein
2018-10-29 14:27 ` Paul E. McKenney
2018-10-30 3:44 ` Joel Fernandes
2018-10-30 12:58 ` Paul E. McKenney
2018-10-30 22:21 ` Joel Fernandes
2018-10-31 18:22 ` Paul E. McKenney
2018-11-02 19:43 ` Paul E. McKenney
2018-11-26 13:55 ` Ran Rozenstein
2018-11-26 19:00 ` Paul E. McKenney [this message]
2018-08-29 22:20 ` [PATCH tip/core/rcu 03/19] rcutorture: Test extended "rcu" read-side critical sections Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 04/19] rcu: Allow processing deferred QSes for exiting RCU-preempt readers Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 05/19] rcu: Remove now-unused ->b.exp_need_qs field from the rcu_special union Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 06/19] rcu: Add warning to detect half-interrupts Paul E. McKenney
2019-03-11 13:39 ` Joel Fernandes
2019-03-11 22:29 ` Paul E. McKenney
2019-03-12 15:05 ` Joel Fernandes
2019-03-12 15:20 ` Paul E. McKenney
2019-03-13 15:09 ` Joel Fernandes
2019-03-13 15:27 ` Steven Rostedt
2019-03-13 15:51 ` Paul E. McKenney
2019-03-13 16:51 ` Steven Rostedt
2019-03-13 18:07 ` Paul E. McKenney
2019-03-14 12:31 ` Joel Fernandes
2019-03-14 13:36 ` Steven Rostedt
2019-03-14 13:37 ` Steven Rostedt
2019-03-14 21:27 ` Joel Fernandes
2019-03-15 7:31 ` Byungchul Park
2019-03-15 7:44 ` Byungchul Park
2019-03-15 13:46 ` Joel Fernandes
2018-08-29 22:20 ` [PATCH tip/core/rcu 07/19] rcu: Apply RCU-bh QSes to RCU-sched and RCU-preempt when safe Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 08/19] rcu: Report expedited grace periods at context-switch time Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 09/19] rcu: Define RCU-bh update API in terms of RCU Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 10/19] rcu: Update comments and help text for no more RCU-bh updaters Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 11/19] rcu: Drop "wake" parameter from rcu_report_exp_rdp() Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 12/19] rcu: Fix typo in rcu_get_gp_kthreads_prio() header comment Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 13/19] rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 14/19] rcu: Express Tiny RCU updates in terms of RCU rather than RCU-sched Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 15/19] rcu: Remove RCU_STATE_INITIALIZER() Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 16/19] rcu: Eliminate rcu_state structure's ->call field Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 17/19] rcu: Remove rcu_state structure's ->rda field Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 18/19] rcu: Remove rcu_state_p pointer to default rcu_state structure Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 19/19] rcu: Remove rcu_data_p pointer to default rcu_data structure Paul E. McKenney
2018-08-29 22:22 ` [PATCH tip/core/rcu 0/19] RCU flavor-consolidation changes for v4.20/v5.0 Paul E. McKenney
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