From: Christoph Hellwig <hch@infradead.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, tglx@linutronix.de,
linux-kernel@vger.kernel.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
paulmck@kernel.org, frederic@kernel.org,
tsbogend@alpha.franken.de, axboe@kernel.dk, rjw@rjwysocki.net,
daniel.lezcano@linaro.org, dchickles@marvell.com,
davem@davemloft.net, kuba@kernel.org, daniel.thompson@linaro.org,
gerald.schaefer@de.ibm.com
Subject: Re: [PATCH 6/6] smp: Cleanup smp_call_function*()
Date: Wed, 17 Jun 2020 01:23:49 -0700 [thread overview]
Message-ID: <20200617082349.GA19894@infradead.org> (raw)
In-Reply-To: <20200615131143.434079683@infradead.org>
> -static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
> +static DEFINE_PER_CPU(call_single_data_t, backtrace_csd) = CSD_INIT(handle_backtrace, NULL);
> static struct cpumask backtrace_csd_busy;
Besides the crazy long line: does assigning to a DEFINE_PER_CPU
really work and initialize all the members?
> @@ -178,9 +178,7 @@ static void zpci_handle_fallback_irq(voi
> if (atomic_inc_return(&cpu_data->scheduled) > 1)
> continue;
>
> - cpu_data->csd.func = zpci_handle_remote_irq;
> - cpu_data->csd.info = &cpu_data->scheduled;
> - cpu_data->csd.flags = 0;
> + cpu_data->csd = CSD_INIT(zpci_handle_remote_irq, &cpu_data->scheduled);
This looks weird. I'd much rather see an initialization ala INIT_WORK:
INIT_CSD(&cpu_data->csd, zpci_handle_remote_irq,
&cpu_data->scheduled);
Also for many smp_call_function_* users it would be trivial and actually
lead to nicer code if the data argument went away and we'd just use
container_of to get to the containing structure. For the remaining
ones we can trivially general a container strucuture that has the
extra data pointer.
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -629,9 +629,7 @@ void blk_mq_force_complete_rq(struct req
> shared = cpus_share_cache(cpu, ctx->cpu);
>
> if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
> - rq->csd.func = __blk_mq_complete_request_remote;
> - rq->csd.info = rq;
> - rq->csd.flags = 0;
> + rq->csd = CSD_INIT(__blk_mq_complete_request_remote, rq);
> smp_call_function_single_async(ctx->cpu, &rq->csd);
> } else {
> q->mq_ops->complete(rq);
> --- a/block/blk-softirq.c
> +++ b/block/blk-softirq.c
> @@ -57,13 +57,8 @@ static void trigger_softirq(void *data)
> static int raise_blk_irq(int cpu, struct request *rq)
> {
> if (cpu_online(cpu)) {
> - call_single_data_t *data = &rq->csd;
> -
> - data->func = trigger_softirq;
> - data->info = rq;
> - data->flags = 0;
> -
> - smp_call_function_single_async(cpu, data);
> + rq->csd = CSD_INIT(trigger_softirq, rq);
> + smp_call_function_single_async(cpu, &rq->csd);
> return 0;
> }
FYI, I rewrote much of the blk code in this series:
https://lore.kernel.org/linux-block/20200611064452.12353-1-hch@lst.de/T/#t
that you also were Cced on.
> struct __call_single_data {
> - union {
> - struct __call_single_node node;
> - struct {
> - struct llist_node llist;
> - unsigned int flags;
> - };
> - };
> + struct __call_single_node node;
> smp_call_func_t func;
> void *info;
> };
Can we rename this to struct call_single_data without the __prefix
and switch all the users you touch anyway away from the typedef?
next prev parent reply other threads:[~2020-06-17 8:23 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 12:56 [PATCH 0/6] sched: TTWU, IPI, and assorted stuff Peter Zijlstra
2020-06-15 12:56 ` [PATCH 1/6] sched: Fix ttwu_queue_cond() Peter Zijlstra
2020-06-15 13:34 ` Peter Zijlstra
2020-06-15 16:45 ` Paul E. McKenney
2020-06-15 22:58 ` Paul E. McKenney
2020-06-22 9:11 ` Mel Gorman
2020-06-22 9:41 ` Peter Zijlstra
2020-06-15 12:56 ` [PATCH 2/6] sched: Verify some SMP assumptions Peter Zijlstra
2020-06-15 12:56 ` [PATCH 3/6] sched: s/WF_ON_RQ/WQ_ON_CPU/ Peter Zijlstra
2020-06-22 9:13 ` Mel Gorman
2020-06-15 12:56 ` [PATCH 4/6] smp, irq_work: Continue smp_call_function*() and irq_work*() integration Peter Zijlstra
2020-06-15 12:56 ` [PATCH 5/6] irq_work: Cleanup Peter Zijlstra
2020-06-16 15:16 ` Petr Mladek
2020-06-15 12:57 ` [PATCH 6/6] smp: Cleanup smp_call_function*() Peter Zijlstra
2020-06-15 14:34 ` Jens Axboe
2020-06-15 16:04 ` Daniel Thompson
2020-06-17 8:23 ` Christoph Hellwig [this message]
2020-06-17 9:00 ` Peter Zijlstra
2020-06-17 11:04 ` Peter Zijlstra
2020-06-18 6:51 ` Christoph Hellwig
2020-06-18 16:25 ` Peter Zijlstra
2020-06-15 16:23 ` [PATCH 0/6] sched: TTWU, IPI, and assorted stuff Paul E. McKenney
2020-06-15 16:40 ` Peter Zijlstra
2020-06-15 17:21 ` Paul E. McKenney
2020-06-15 19:11 ` Peter Zijlstra
2020-06-15 19:55 ` Paul E. McKenney
2020-06-16 16:31 ` Paul E. McKenney
2020-06-16 17:04 ` Peter Zijlstra
2020-06-16 17:17 ` Peter Zijlstra
2020-06-16 17:53 ` Paul E. McKenney
2020-06-19 13:44 ` Peter Zijlstra
2020-06-19 17:20 ` Paul E. McKenney
2020-06-19 17:48 ` Paul E. McKenney
2020-06-19 18:11 ` Peter Zijlstra
2020-06-19 18:46 ` Paul E. McKenney
2020-06-20 18:46 ` Paul E. McKenney
2020-06-16 17:51 ` Paul E. McKenney
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