Re: [PATCH 25/36] time/tick-broadcast: Remove RCU_NONIDLE usage
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- To: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
- Subject: Re: [PATCH 25/36] time/tick-broadcast: Remove RCU_NONIDLE usage
- From: Mark Rutland <mark.rutland@xxxxxxx>
- Date: Tue, 14 Jun 2022 17:28:02 +0100
- Cc: rth@xxxxxxxxxxxxxxx, ink@xxxxxxxxxxxxxxxxxxxx, mattst88@xxxxxxxxx, vgupta@xxxxxxxxxx, linux@xxxxxxxxxxxxxxx, ulli.kroll@xxxxxxxxxxxxxx, linus.walleij@xxxxxxxxxx, shawnguo@xxxxxxxxxx, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>, kernel@xxxxxxxxxxxxxx, festevam@xxxxxxxxx, linux-imx@xxxxxxx, tony@xxxxxxxxxxx, khilman@xxxxxxxxxx, catalin.marinas@xxxxxxx, will@xxxxxxxxxx, guoren@xxxxxxxxxx, bcain@xxxxxxxxxxx, chenhuacai@xxxxxxxxxx, kernel@xxxxxxxxxx, geert@xxxxxxxxxxxxxx, sammy@xxxxxxxxx, monstr@xxxxxxxxx, tsbogend@xxxxxxxxxxxxxxxx, dinguyen@xxxxxxxxxx, jonas@xxxxxxxxxxxx, stefan.kristiansson@xxxxxxxxxxxxx, shorne@xxxxxxxxx, James.Bottomley@xxxxxxxxxxxxxxxxxxxxx, deller@xxxxxx, mpe@xxxxxxxxxxxxxx, benh@xxxxxxxxxxxxxxxxxxx, paulus@xxxxxxxxx, paul.walmsley@xxxxxxxxxx, palmer@xxxxxxxxxxx, aou@xxxxxxxxxxxxxxxxx, hca@xxxxxxxxxxxxx, gor@xxxxxxxxxxxxx, agordeev@xxxxxxxxxxxxx, borntraeger@xxxxxxxxxxxxx, svens@xxxxxxxxxxxxx, ysato@xxxxxxxxxxxxx, dalias@xxxxxxxx, davem@xxxxxxxxxxxxx, richard@xxxxxx, anton.ivanov@xxxxxxxxxxxxxxxxxx, johannes@xxxxxxxxxxxxxxxx, tglx@xxxxxxxxxxxxx, mingo@xxxxxxxxxx, bp@xxxxxxxxx, dave.hansen@xxxxxxxxxxxxxxx, x86@xxxxxxxxxx, hpa@xxxxxxxxx, acme@xxxxxxxxxx, alexander.shishkin@xxxxxxxxxxxxxxx, jolsa@xxxxxxxxxx, namhyung@xxxxxxxxxx, jgross@xxxxxxxx, srivatsa@xxxxxxxxxxxxx, amakhalov@xxxxxxxxxx, pv-drivers@xxxxxxxxxx, boris.ostrovsky@xxxxxxxxxx, chris@xxxxxxxxxx, jcmvbkbc@xxxxxxxxx, rafael@xxxxxxxxxx, lenb@xxxxxxxxxx, pavel@xxxxxx, gregkh@xxxxxxxxxxxxxxxxxxx, mturquette@xxxxxxxxxxxx, sboyd@xxxxxxxxxx, daniel.lezcano@xxxxxxxxxx, lpieralisi@xxxxxxxxxx, sudeep.holla@xxxxxxx, agross@xxxxxxxxxx, bjorn.andersson@xxxxxxxxxx, anup@xxxxxxxxxxxxxx, thierry.reding@xxxxxxxxx, jonathanh@xxxxxxxxxx, jacob.jun.pan@xxxxxxxxxxxxxxx, Arnd Bergmann <arnd@xxxxxxxx>, yury.norov@xxxxxxxxx, andriy.shevchenko@xxxxxxxxxxxxxxx, linux@xxxxxxxxxxxxxxxxxx, rostedt@xxxxxxxxxxx, pmladek@xxxxxxxx, senozhatsky@xxxxxxxxxxxx, john.ogness@xxxxxxxxxxxxx, paulmck@xxxxxxxxxx, frederic@xxxxxxxxxx, quic_neeraju@xxxxxxxxxxx, josh@xxxxxxxxxxxxxxxx, mathieu.desnoyers@xxxxxxxxxxxx, jiangshanlai@xxxxxxxxx, joel@xxxxxxxxxxxxxxxxx, juri.lelli@xxxxxxxxxx, vincent.guittot@xxxxxxxxxx, dietmar.eggemann@xxxxxxx, bsegall@xxxxxxxxxx, mgorman@xxxxxxx, bristot@xxxxxxxxxx, vschneid@xxxxxxxxxx, jpoimboe@xxxxxxxxxx, linux-alpha@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-snps-arc@xxxxxxxxxxxxxxxxxxx, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-omap@xxxxxxxxxxxxxxx, linux-csky@xxxxxxxxxxxxxxx, linux-hexagon@xxxxxxxxxxxxxxx, linux-ia64@xxxxxxxxxxxxxxx, linux-m68k@xxxxxxxxxxxxxxx, linux-mips@xxxxxxxxxxxxxxx, openrisc@xxxxxxxxxxxxxxxxxxxx, linux-parisc@xxxxxxxxxxxxxxx, linuxppc-dev@xxxxxxxxxxxxxxxx, linux-riscv@xxxxxxxxxxxxxxxxxxx, linux-s390@xxxxxxxxxxxxxxx, linux-sh@xxxxxxxxxxxxxxx, sparclinux@xxxxxxxxxxxxxxx, linux-um@xxxxxxxxxxxxxxxxxxx, linux-perf-users@xxxxxxxxxxxxxxx, virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, linux-xtensa@xxxxxxxxxxxxxxxx, linux-acpi@xxxxxxxxxxxxxxx, linux-pm@xxxxxxxxxxxxxxx, linux-clk@xxxxxxxxxxxxxxx, linux-arm-msm@xxxxxxxxxxxxxxx, linux-tegra@xxxxxxxxxxxxxxx, linux-arch@xxxxxxxxxxxxxxx, rcu@xxxxxxxxxxxxxxx
- In-reply-to: <20220608144517.507286638@infradead.org>
- References: <20220608142723.103523089@infradead.org> <20220608144517.507286638@infradead.org>
On Wed, Jun 08, 2022 at 04:27:48PM +0200, Peter Zijlstra wrote:
> No callers left that have already disabled RCU.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Mark.
> ---
> kernel/time/tick-broadcast-hrtimer.c | 29 ++++++++++++-----------------
> 1 file changed, 12 insertions(+), 17 deletions(-)
>
> --- a/kernel/time/tick-broadcast-hrtimer.c
> +++ b/kernel/time/tick-broadcast-hrtimer.c
> @@ -56,25 +56,20 @@ static int bc_set_next(ktime_t expires,
> * hrtimer callback function is currently running, then
> * hrtimer_start() cannot move it and the timer stays on the CPU on
> * which it is assigned at the moment.
> + */
> + hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD);
> + /*
> + * The core tick broadcast mode expects bc->bound_on to be set
> + * correctly to prevent a CPU which has the broadcast hrtimer
> + * armed from going deep idle.
> *
> - * As this can be called from idle code, the hrtimer_start()
> - * invocation has to be wrapped with RCU_NONIDLE() as
> - * hrtimer_start() can call into tracing.
> + * As tick_broadcast_lock is held, nothing can change the cpu
> + * base which was just established in hrtimer_start() above. So
> + * the below access is safe even without holding the hrtimer
> + * base lock.
> */
> - RCU_NONIDLE( {
> - hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD);
> - /*
> - * The core tick broadcast mode expects bc->bound_on to be set
> - * correctly to prevent a CPU which has the broadcast hrtimer
> - * armed from going deep idle.
> - *
> - * As tick_broadcast_lock is held, nothing can change the cpu
> - * base which was just established in hrtimer_start() above. So
> - * the below access is safe even without holding the hrtimer
> - * base lock.
> - */
> - bc->bound_on = bctimer.base->cpu_base->cpu;
> - } );
> + bc->bound_on = bctimer.base->cpu_base->cpu;
> +
> return 0;
> }
>
>
>
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