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Date: Tue, 27 Mar 2007 15:43:57 -0700
From: Randy Dunlap <rdunlap@...otime.net>
To: Jeremy Fitzhardinge <jeremy@...p.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Virtualization Mailing List <virtualization@...ts.osdl.org>,
Jan Beulich <jbeulich@...ell.com>,
Stephane Eranian <eranian@....hp.com>, Andi Kleen <ak@...e.de>,
Ingo Molnar <mingo@...e.hu>,
"Randy.Dunlap" <rdunlap@...otime.net>
Subject: Re: [PATCH] Simplify smp_call_function*() by using common
implementation
On Tue, 27 Mar 2007 15:13:29 -0700 Jeremy Fitzhardinge wrote:
> smp_call_function and smp_call_function_single are almost complete
> duplicates of the same logic. This patch combines them by
> implementing them in terms of the more general
> smp_call_function_mask().
>
> [ Jan, Andi: This only changes arch/i386; can x86_64 be changed in the
> same way? ]
>
> [ Rebased onto Jan's x86_64-mm-consolidate-smp_send_stop patch ]
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy@...source.com>
> Cc: Jan Beulich <jbeulich@...ell.com>
> Cc: Stephane Eranian <eranian@....hp.com>
> Cc: Andrew Morton <akpm@...l.org>
> Cc: Andi Kleen <ak@...e.de>
> Cc: "Randy.Dunlap" <rdunlap@...otime.net>
> Cc: Ingo Molnar <mingo@...e.hu>
>
> ---
> arch/i386/kernel/smp.c | 177 +++++++++++++++++++++++-------------------------
> 1 file changed, 86 insertions(+), 91 deletions(-)
>
> ===================================================================
> --- a/arch/i386/kernel/smp.c
> +++ b/arch/i386/kernel/smp.c
> @@ -544,6 +559,34 @@ static void __smp_call_function(void (*f
> if (wait)
> while (atomic_read(&data.finished) != cpus)
> cpu_relax();
> +
> + return 0;
> +}
> +
> +/**
> + * smp_call_function_mask(): Run a function on a set of other CPUs.
> + * @mask: The set of cpus to run on. Must not include the current cpu.
> + * @func: The function to run. This must be fast and non-blocking.
> + * @info: An arbitrary pointer to pass to the function.
> + * @wait: If true, wait (atomically) until function has completed on other CPUs.
> + *
> + * Returns 0 on success, else a negative status code. Does not return until
> + * remote CPUs are nearly ready to execute <<func>> or are or have finished.
func() or <what>??
and what does "nearly ready" mean?
> + *
> + * You must not call this function with disabled interrupts or from a
> + * hardware interrupt handler or from a bottom half handler.
> + */
> +int smp_call_function_mask(cpumask_t mask,
> + void (*func)(void *), void *info,
> + int wait)
> +{
> + int ret;
> +
> + spin_lock(&call_lock);
> + ret = __smp_call_function_mask(mask, func, info, wait);
> + spin_unlock(&call_lock);
> +
> + return ret;
> }
>
> /**
> @@ -559,20 +602,43 @@ static void __smp_call_function(void (*f
> * You must not call this function with disabled interrupts or from a
> * hardware interrupt handler or from a bottom half handler.
> */
> -int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
> - int wait)
> -{
> - /* Can deadlock when called with interrupts disabled */
> - WARN_ON(irqs_disabled());
> -
> - /* Holding any lock stops cpus from going down. */
> - spin_lock(&call_lock);
> - __smp_call_function(func, info, nonatomic, wait);
> - spin_unlock(&call_lock);
> -
> - return 0;
> +int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
> + int wait)
> +{
> + return smp_call_function_mask(cpu_online_map, func, info, wait);
> }
> EXPORT_SYMBOL(smp_call_function);
> +
> +/*
/**
> + * smp_call_function_single - Run a function on another CPU
> + * @func: The function to run. This must be fast and non-blocking.
> + * @info: An arbitrary pointer to pass to the function.
> + * @nonatomic: Currently unused.
> + * @wait: If true, wait until function has completed on other CPUs.
> + *
> + * Retrurns 0 on success, else a negative status code.
Returns
> + *
> + * Does not return until the remote CPU is nearly ready to execute <func>
Same comments: what is "nearly ready"? and s/<func>/func()/
> + * or is or has executed.
Huh? or what??
> + */
> +int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
> + int nonatomic, int wait)
> +{
> + /* prevent preemption and reschedule on another processor */
> + int ret;
> + int me = get_cpu();
> + if (cpu == me) {
> + WARN_ON(1);
> + put_cpu();
> + return -EBUSY;
> + }
> +
> + ret = smp_call_function_mask(cpumask_of_cpu(cpu), func, info, wait);
> +
> + put_cpu();
> + return ret;
> +}
> +EXPORT_SYMBOL(smp_call_function_single);
>
> static void stop_this_cpu (void * dummy)
> {
> @@ -641,77 +707,6 @@ fastcall void smp_call_function_interrup
> }
> }
>
> -/*
> - * this function sends a 'generic call function' IPI to one other CPU
> - * in the system.
> - *
> - * cpu is a standard Linux logical CPU number.
> - */
> -static void
> -__smp_call_function_single(int cpu, void (*func) (void *info), void *info,
> - int nonatomic, int wait)
> -{
> - struct call_data_struct data;
> - int cpus = 1;
> -
> - data.func = func;
> - data.info = info;
> - atomic_set(&data.started, 0);
> - data.wait = wait;
> - if (wait)
> - atomic_set(&data.finished, 0);
> -
> - call_data = &data;
> - wmb();
> - /* Send a message to all other CPUs and wait for them to respond */
> - send_IPI_mask(cpumask_of_cpu(cpu), CALL_FUNCTION_VECTOR);
> -
> - /* Wait for response */
> - while (atomic_read(&data.started) != cpus)
> - cpu_relax();
> -
> - if (!wait)
> - return;
> -
> - while (atomic_read(&data.finished) != cpus)
> - cpu_relax();
> -}
> -
> -/*
> - * smp_call_function_single - Run a function on another CPU
> - * @func: The function to run. This must be fast and non-blocking.
> - * @info: An arbitrary pointer to pass to the function.
> - * @nonatomic: Currently unused.
> - * @wait: If true, wait until function has completed on other CPUs.
> - *
> - * Retrurns 0 on success, else a negative status code.
> - *
> - * Does not return until the remote CPU is nearly ready to execute <func>
> - * or is or has executed.
> - */
> -
> -int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
> - int nonatomic, int wait)
> -{
> - /* prevent preemption and reschedule on another processor */
> - int me = get_cpu();
> - if (cpu == me) {
> - WARN_ON(1);
> - put_cpu();
> - return -EBUSY;
> - }
> -
> - /* Can deadlock when called with interrupts disabled */
> - WARN_ON(irqs_disabled());
> -
> - spin_lock_bh(&call_lock);
> - __smp_call_function_single(cpu, func, info, nonatomic, wait);
> - spin_unlock_bh(&call_lock);
> - put_cpu();
> - return 0;
> -}
> -EXPORT_SYMBOL(smp_call_function_single);
> -
> static int convert_apicid_to_cpu(int apic_id)
> {
> int i;
---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***
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