Commit b3a7e98e authored by Gilad Ben-Yossef's avatar Gilad Ben-Yossef Committed by Linus Torvalds
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smp: add func to IPI cpus based on parameter func

Add the on_each_cpu_cond() function that wraps on_each_cpu_mask() and
calculates the cpumask of cpus to IPI by calling a function supplied as a
parameter in order to determine whether to IPI each specific cpu.

The function works around allocation failure of cpumask variable in
CONFIG_CPUMASK_OFFSTACK=y by itereating over cpus sending an IPI a time
via smp_call_function_single().

The function is useful since it allows to seperate the specific code that
decided in each case whether to IPI a specific cpu for a specific request
from the common boilerplate code of handling creating the mask, handling
failures etc.

[ s/gfpflags/gfp_flags/]
[ avoid double-evaluation of `info' (per Michal), parenthesise evaluation of `cond_func']
[ s/CPU/CPUs, use all 80 cols in comment]
Signed-off-by: default avatarGilad Ben-Yossef <>
Cc: Chris Metcalf <>
Cc: Christoph Lameter <>
Acked-by: default avatarPeter Zijlstra <>
Cc: Frederic Weisbecker <>
Cc: Russell King <>
Cc: Pekka Enberg <>
Cc: Matt Mackall <>
Cc: Sasha Levin <>
Cc: Rik van Riel <>
Cc: Andi Kleen <>
Cc: Alexander Viro <>
Cc: Avi Kivity <>
Acked-by: default avatarMichal Nazarewicz <>
Cc: Kosaki Motohiro <>
Cc: Milton Miller <>
Reviewed-by: default avatar"Srivatsa S. Bhat" <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 3fc498f1
......@@ -108,6 +108,15 @@ int on_each_cpu(smp_call_func_t func, void *info, int wait);
void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
void *info, bool wait);
* Call a function on each processor for which the supplied function
* cond_func returns a positive value. This may include the local
* processor.
void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
smp_call_func_t func, void *info, bool wait,
gfp_t gfp_flags);
* Mark the boot cpu "online" so that it can call console drivers in
* printk() and can access its per-cpu storage.
......@@ -153,6 +162,21 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info)
local_irq_enable(); \
} \
} while (0)
* Preemption is disabled here to make sure the cond_func is called under the
* same condtions in UP and SMP.
#define on_each_cpu_cond(cond_func, func, info, wait, gfp_flags)\
do { \
void *__info = (info); \
preempt_disable(); \
if ((cond_func)(0, __info)) { \
local_irq_disable(); \
(func)(__info); \
local_irq_enable(); \
} \
preempt_enable(); \
} while (0)
static inline void smp_send_reschedule(int cpu) { }
#define num_booting_cpus() 1
......@@ -730,3 +730,64 @@ void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
* on_each_cpu_cond(): Call a function on each processor for which
* the supplied function cond_func returns true, optionally waiting
* for all the required CPUs to finish. This may include the local
* processor.
* @cond_func: A callback function that is passed a cpu id and
* the the info parameter. The function is called
* with preemption disabled. The function should
* return a blooean value indicating whether to IPI
* the specified CPU.
* @func: The function to run on all applicable CPUs.
* This must be fast and non-blocking.
* @info: An arbitrary pointer to pass to both functions.
* @wait: If true, wait (atomically) until function has
* completed on other CPUs.
* @gfp_flags: GFP flags to use when allocating the cpumask
* used internally by the function.
* The function might sleep if the GFP flags indicates a non
* atomic allocation is allowed.
* Preemption is disabled to protect against CPUs going offline but not online.
* CPUs going online during the call will not be seen or sent an IPI.
* You must not call this function with disabled interrupts or
* from a hardware interrupt handler or from a bottom half handler.
void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
smp_call_func_t func, void *info, bool wait,
gfp_t gfp_flags)
cpumask_var_t cpus;
int cpu, ret;
might_sleep_if(gfp_flags & __GFP_WAIT);
if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
if (cond_func(cpu, info))
cpumask_set_cpu(cpu, cpus);
on_each_cpu_mask(cpus, func, info, wait);
} else {
* No free cpumask, bother. No matter, we'll
* just have to IPI them one by one.
if (cond_func(cpu, info)) {
ret = smp_call_function_single(cpu, func,
info, wait);
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