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Message-ID: <ACE814E2-5986-44AE-920C-1EA241D2E12D@vmware.com>
Date: Thu, 18 Feb 2021 09:36:09 +0000
From: Nadav Amit <namit@...are.com>
To: Christoph Hellwig <hch@...radead.org>
CC: Thomas Gleixner <tglx@...utronix.de>,
LKML <linux-kernel@...r.kernel.org>,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Rik van Riel <riel@...riel.com>,
Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH v5 1/8] smp: Run functions concurrently in
smp_call_function_many_cond()
> On Feb 18, 2021, at 12:09 AM, Christoph Hellwig <hch@...radead.org> wrote:
>
> On Tue, Feb 09, 2021 at 02:16:46PM -0800, Nadav Amit wrote:
>> +/*
>> + * Flags to be used as scf_flags argument of smp_call_function_many_cond().
>> + */
>> +#define SCF_WAIT (1U << 0) /* Wait until function execution completed */
>> +#define SCF_RUN_LOCAL (1U << 1) /* Run also locally if local cpu is set in cpumask */
>
> Can you move the comments on top of the defines to avoid the crazy
> long lines?
>
>> + if (cpu_online(this_cpu) && !oops_in_progress && !early_boot_irqs_disabled)
>
> Another pointlessly overly long line, with various more following.
>
>> EXPORT_SYMBOL(on_each_cpu_cond_mask);
>
> This isn't used by any modular code, so maybe throw in a patch to drop
> the export?
I prefer to export on_each_cpu_cond_mask() and instead turn the users
(on_each_cpu(), on_each_cpu_mask() and on_each_cpu_cond()) into inline
functions in smp.h. Otherwise, the call-chain becomes longer for no reason.
Let me know if you object.
So I will add something like:
-- >8 --
Author: Nadav Amit <namit@...are.com>
Date: Tue Feb 16 11:04:30 2021 -0800
smp: inline on_each_cpu_cond() and on_each_cpu_cond_mask()
Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Nadav Amit <namit@...are.com>
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 70c6f6284dcf..84a0b4828f66 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,30 +50,52 @@ extern unsigned int total_cpus;
int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
int wait);
+void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
+ void *info, bool wait, const struct cpumask *mask);
+
+int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+
/*
* Call a function on all processors
*/
-void on_each_cpu(smp_call_func_t func, void *info, int wait);
+static inline void on_each_cpu(smp_call_func_t func, void *info, int wait)
+{
+ on_each_cpu_cond_mask(NULL, func, info, wait, cpu_online_mask);
+}
-/*
- * Call a function on processors specified by mask, which might include
- * the local one.
+/**
+ * on_each_cpu_mask(): Run a function on processors specified by
+ * cpumask, which may include the local processor.
+ * @mask: The set of cpus to run on (only runs on online subset).
+ * @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.
+ *
+ * If @wait is true, then returns once @func has returned.
+ *
+ * You must not call this function with disabled interrupts or from a
+ * hardware interrupt handler or from a bottom half handler. The
+ * exception is that it may be used during early boot while
+ * early_boot_irqs_disabled is set.
*/
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
- void *info, bool wait);
+static inline void on_each_cpu_mask(const struct cpumask *mask,
+ smp_call_func_t func, void *info, bool wait)
+{
+ on_each_cpu_cond_mask(NULL, func, info, wait, mask);
+}
/*
* Call a function on each processor for which the supplied function
* cond_func returns a positive value. This may include the local
- * processor.
+ * processor. May be used during early boot while early_boot_irqs_disabled is
+ * set. Use local_irq_save/restore() instead of local_irq_disable/enable().
*/
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
- void *info, bool wait);
-
-void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
- void *info, bool wait, const struct cpumask *mask);
-
-int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+static inline void on_each_cpu_cond(smp_cond_func_t cond_func,
+ smp_call_func_t func, void *info, bool wait)
+{
+ on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
+}
#ifdef CONFIG_SMP
diff --git a/kernel/smp.c b/kernel/smp.c
index 629f1f7b80db..a75f3d1dd1b7 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -843,55 +843,6 @@ void __init smp_init(void)
smp_cpus_done(setup_max_cpus);
}
-/*
- * Call a function on all processors. May be used during early boot while
- * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
- * of local_irq_disable/enable().
- */
-void on_each_cpu(smp_call_func_t func, void *info, int wait)
-{
- unsigned long flags;
-
- preempt_disable();
- smp_call_function(func, info, wait);
- local_irq_save(flags);
- func(info);
- local_irq_restore(flags);
- preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu);
-
-/**
- * on_each_cpu_mask(): Run a function on processors specified by
- * cpumask, which may include the local processor.
- * @mask: The set of cpus to run on (only runs on online subset).
- * @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.
- *
- * If @wait is true, then returns once @func has returned.
- *
- * You must not call this function with disabled interrupts or from a
- * hardware interrupt handler or from a bottom half handler. The
- * exception is that it may be used during early boot while
- * early_boot_irqs_disabled is set.
- */
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
- void *info, bool wait)
-{
- unsigned int scf_flags;
-
- scf_flags = SCF_RUN_LOCAL;
- if (wait)
- scf_flags |= SCF_WAIT;
-
- preempt_disable();
- smp_call_function_many_cond(mask, func, info, scf_flags, NULL);
- preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu_mask);
-
/*
* on_each_cpu_cond(): Call a function on each processor for which
* the supplied function cond_func returns true, optionally waiting
@@ -928,13 +879,6 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
}
EXPORT_SYMBOL(on_each_cpu_cond_mask);
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
- void *info, bool wait)
-{
- on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
-}
-EXPORT_SYMBOL(on_each_cpu_cond);
-
static void do_nothing(void *unused)
{
}
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