Re: [PATCH v2 7/7] sparc/smp: Remove on-stack cpumask var

From: Dawei Li
Date: Mon Apr 22 2024 - 02:20:45 EST

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In reply to: Sam Ravnborg: "Re: [PATCH v2 7/7] sparc/smp: Remove on-stack cpumask var"
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Hi Sam,

Thanks for review.

On Sat, Apr 20, 2024 at 01:42:07PM +0200, Sam Ravnborg wrote:
> Hi Dawei
>
> On Sat, Apr 20, 2024 at 01:15:47PM +0800, Dawei Li wrote:
> > In general it's preferable to avoid placing cpumasks on the stack, as
> > for large values of NR_CPUS these can consume significant amounts of
> > stack space and make stack overflows more likely.
> >
> > - Change prototype of sparc32_ipi_ops::cross_call() so that it takes
> > const cpumask * arg and all its callers accordingly.
> >
> > - As for all cross_call() implementations, divide cpumask_test_cpu() call
> > into several sub calls to avoid on-stack cpumask var.
> >
> > Signed-off-by: Dawei Li <dawei.li@xxxxxxxxxxxx>
>
> The code changes looks ok from a quick look.
> But we have a bunch of patches pending touching or removing the same
> files. On top of this, the right approach would be to take a
> look at code from a higher level.
>
> In other words - I advise to drop this, and maybe re-visit in a few
> months after the pending patches has hit -next.
>
> Sorry for asking you to look as this.

It's OK :), I will drop this commit until your patch series are applied.

Thanks,

Dawei

>
> Sam
>
> > ---
> > arch/sparc/include/asm/smp_32.h | 12 ++++++------
> > arch/sparc/kernel/kernel.h | 11 +++++++++++
> > arch/sparc/kernel/leon_smp.c | 11 ++++-------
> > arch/sparc/kernel/sun4d_smp.c | 10 ++++------
> > arch/sparc/kernel/sun4m_smp.c | 10 ++++------
> > 5 files changed, 29 insertions(+), 25 deletions(-)
> >
> > diff --git a/arch/sparc/include/asm/smp_32.h b/arch/sparc/include/asm/smp_32.h
> > index 2cf7971d7f6c..9b6a166f6a57 100644
> > --- a/arch/sparc/include/asm/smp_32.h
> > +++ b/arch/sparc/include/asm/smp_32.h
> > @@ -54,7 +54,7 @@ void smp_bogo(struct seq_file *);
> > void smp_info(struct seq_file *);
> >
> > struct sparc32_ipi_ops {
> > - void (*cross_call)(void *func, cpumask_t mask, unsigned long arg1,
> > + void (*cross_call)(void *func, const cpumask_t *mask, unsigned long arg1,
> > unsigned long arg2, unsigned long arg3,
> > unsigned long arg4);
> > void (*resched)(int cpu);
> > @@ -65,29 +65,29 @@ extern const struct sparc32_ipi_ops *sparc32_ipi_ops;
> >
> > static inline void xc0(void *func)
> > {
> > - sparc32_ipi_ops->cross_call(func, *cpu_online_mask, 0, 0, 0, 0);
> > + sparc32_ipi_ops->cross_call(func, cpu_online_mask, 0, 0, 0, 0);
> > }
> >
> > static inline void xc1(void *func, unsigned long arg1)
> > {
> > - sparc32_ipi_ops->cross_call(func, *cpu_online_mask, arg1, 0, 0, 0);
> > + sparc32_ipi_ops->cross_call(func, cpu_online_mask, arg1, 0, 0, 0);
> > }
> > static inline void xc2(void *func, unsigned long arg1, unsigned long arg2)
> > {
> > - sparc32_ipi_ops->cross_call(func, *cpu_online_mask, arg1, arg2, 0, 0);
> > + sparc32_ipi_ops->cross_call(func, cpu_online_mask, arg1, arg2, 0, 0);
> > }
> >
> > static inline void xc3(void *func, unsigned long arg1, unsigned long arg2,
> > unsigned long arg3)
> > {
> > - sparc32_ipi_ops->cross_call(func, *cpu_online_mask,
> > + sparc32_ipi_ops->cross_call(func, cpu_online_mask,
> > arg1, arg2, arg3, 0);
> > }
> >
> > static inline void xc4(void *func, unsigned long arg1, unsigned long arg2,
> > unsigned long arg3, unsigned long arg4)
> > {
> > - sparc32_ipi_ops->cross_call(func, *cpu_online_mask,
> > + sparc32_ipi_ops->cross_call(func, cpu_online_mask,
> > arg1, arg2, arg3, arg4);
> > }
> >
> > diff --git a/arch/sparc/kernel/kernel.h b/arch/sparc/kernel/kernel.h
> > index a8fb7c0bf053..36747e8f7e36 100644
> > --- a/arch/sparc/kernel/kernel.h
> > +++ b/arch/sparc/kernel/kernel.h
> > @@ -4,6 +4,7 @@
> >
> > #include <linux/interrupt.h>
> > #include <linux/ftrace.h>
> > +#include <linux/smp.h>
> >
> > #include <asm/traps.h>
> > #include <asm/head.h>
> > @@ -75,6 +76,16 @@ int sparc32_classify_syscall(unsigned int syscall);
> > #endif
> >
> > #ifdef CONFIG_SPARC32
> > +
> > +#ifdef CONFIG_SMP
> > +static inline bool cpu_for_ipi(const cpumask_t *mask, unsigned int cpu)
> > +{
> > + return cpumask_test_cpu(cpu, mask) &&
> > + cpumask_test_cpu(cpu, cpu_online_mask) &&
> > + cpu != smp_processor_id();
> > +}
> > +#endif /* CONFIG_SMP */
> > +
> > /* setup_32.c */
> > struct linux_romvec;
> > void sparc32_start_kernel(struct linux_romvec *rp);
> > diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
> > index 1ee393abc463..291884c8d82a 100644
> > --- a/arch/sparc/kernel/leon_smp.c
> > +++ b/arch/sparc/kernel/leon_smp.c
> > @@ -372,7 +372,7 @@ static struct smp_funcall {
> > static DEFINE_SPINLOCK(cross_call_lock);
> >
> > /* Cross calls must be serialized, at least currently. */
> > -static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> > +static void leon_cross_call(void *func, const cpumask_t *mask, unsigned long arg1,
> > unsigned long arg2, unsigned long arg3,
> > unsigned long arg4)
> > {
> > @@ -403,14 +403,11 @@ static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> > {
> > register int i;
> >
> > - cpumask_clear_cpu(smp_processor_id(), &mask);
> > - cpumask_and(&mask, cpu_online_mask, &mask);
> > for (i = 0; i <= high; i++) {
> > - if (cpumask_test_cpu(i, &mask)) {
> > + if (cpu_for_ipi(mask, i)) {
> > ccall_info.processors_in[i] = 0;
> > ccall_info.processors_out[i] = 0;
> > leon_send_ipi(i, LEON3_IRQ_CROSS_CALL);
> > -
> > }
> > }
> > }
> > @@ -420,7 +417,7 @@ static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> >
> > i = 0;
> > do {
> > - if (!cpumask_test_cpu(i, &mask))
> > + if (!cpu_for_ipi(mask, i))
> > continue;
> >
> > while (!ccall_info.processors_in[i])
> > @@ -429,7 +426,7 @@ static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> >
> > i = 0;
> > do {
> > - if (!cpumask_test_cpu(i, &mask))
> > + if (!cpu_for_ipi(mask, i))
> > continue;
> >
> > while (!ccall_info.processors_out[i])
> > diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
> > index 9a62a5cf3337..7dc57ca05728 100644
> > --- a/arch/sparc/kernel/sun4d_smp.c
> > +++ b/arch/sparc/kernel/sun4d_smp.c
> > @@ -281,7 +281,7 @@ static struct smp_funcall {
> > static DEFINE_SPINLOCK(cross_call_lock);
> >
> > /* Cross calls must be serialized, at least currently. */
> > -static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> > +static void sun4d_cross_call(void *func, const cpumask_t *mask, unsigned long arg1,
> > unsigned long arg2, unsigned long arg3,
> > unsigned long arg4)
> > {
> > @@ -315,10 +315,8 @@ static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> > {
> > register int i;
> >
> > - cpumask_clear_cpu(smp_processor_id(), &mask);
> > - cpumask_and(&mask, cpu_online_mask, &mask);
> > for (i = 0; i <= high; i++) {
> > - if (cpumask_test_cpu(i, &mask)) {
> > + if (cpu_for_ipi(mask, i)) {
> > ccall_info.processors_in[i] = 0;
> > ccall_info.processors_out[i] = 0;
> > sun4d_send_ipi(i, IRQ_CROSS_CALL);
> > @@ -331,7 +329,7 @@ static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> >
> > i = 0;
> > do {
> > - if (!cpumask_test_cpu(i, &mask))
> > + if (!cpu_for_ipi(mask, i))
> > continue;
> > while (!ccall_info.processors_in[i])
> > barrier();
> > @@ -339,7 +337,7 @@ static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> >
> > i = 0;
> > do {
> > - if (!cpumask_test_cpu(i, &mask))
> > + if (!cpu_for_ipi(mask, i))
> > continue;
> > while (!ccall_info.processors_out[i])
> > barrier();
> > diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
> > index 056df034e79e..3f43f64e3489 100644
> > --- a/arch/sparc/kernel/sun4m_smp.c
> > +++ b/arch/sparc/kernel/sun4m_smp.c
> > @@ -170,7 +170,7 @@ static struct smp_funcall {
> > static DEFINE_SPINLOCK(cross_call_lock);
> >
> > /* Cross calls must be serialized, at least currently. */
> > -static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> > +static void sun4m_cross_call(void *func, const cpumask_t *mask, unsigned long arg1,
> > unsigned long arg2, unsigned long arg3,
> > unsigned long arg4)
> > {
> > @@ -191,10 +191,8 @@ static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> > {
> > register int i;
> >
> > - cpumask_clear_cpu(smp_processor_id(), &mask);
> > - cpumask_and(&mask, cpu_online_mask, &mask);
> > for (i = 0; i < ncpus; i++) {
> > - if (cpumask_test_cpu(i, &mask)) {
> > + if (cpu_for_ipi(mask, i)) {
> > ccall_info.processors_in[i] = 0;
> > ccall_info.processors_out[i] = 0;
> > sun4m_send_ipi(i, IRQ_CROSS_CALL);
> > @@ -210,7 +208,7 @@ static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> >
> > i = 0;
> > do {
> > - if (!cpumask_test_cpu(i, &mask))
> > + if (!cpu_for_ipi(mask, i))
> > continue;
> > while (!ccall_info.processors_in[i])
> > barrier();
> > @@ -218,7 +216,7 @@ static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
> >
> > i = 0;
> > do {
> > - if (!cpumask_test_cpu(i, &mask))
> > + if (!cpu_for_ipi(mask, i))
> > continue;
> > while (!ccall_info.processors_out[i])
> > barrier();
> > --
> > 2.27.0
>

Next message: Edward Liaw: "[PATCH 6.6.y] selftests/timers/posix_timers: Reimplement check_timer_distribution()"
Previous message: Peng Fan: "RE: [PATCH v2 00/12] arm64: dts: imx93: various update"
In reply to: Sam Ravnborg: "Re: [PATCH v2 7/7] sparc/smp: Remove on-stack cpumask var"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]