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[PATCH] x86_64/i386: Remove preempt disable calls in lowlevel IPI
I noticed that some lowlevel send_IPI_mask helpers had a hotplug/preempt race whereupon the cpu_online_map was read before disabling preemption; ... cpumask_t mask = cpu_online_map; int cpu = get_cpu(); cpu_clear(cpu, mask); ... But then i realised that there is no need for these lowlevel functions to be going through all this trouble when all the callers are already made hotplug/preempt safe. Signed-off-by: Zwane Mwaikambo <zwane@arm.linux.org.uk> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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73ca5358aa
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3 changed files with 6 additions and 13 deletions
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@ -72,14 +72,11 @@ static void cluster_send_IPI_mask(cpumask_t mask, int vector)
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static void cluster_send_IPI_allbutself(int vector)
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{
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cpumask_t mask = cpu_online_map;
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int me = get_cpu(); /* Ensure we are not preempted when we clear */
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cpu_clear(me, mask);
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cpu_clear(smp_processor_id(), mask);
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if (!cpus_empty(mask))
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cluster_send_IPI_mask(mask, vector);
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put_cpu();
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}
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static void cluster_send_IPI_all(int vector)
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@ -83,12 +83,11 @@ static void flat_send_IPI_allbutself(int vector)
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__send_IPI_shortcut(APIC_DEST_ALLBUT, vector,APIC_DEST_LOGICAL);
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#else
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cpumask_t allbutme = cpu_online_map;
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int me = get_cpu(); /* Ensure we are not preempted when we clear */
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cpu_clear(me, allbutme);
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cpu_clear(smp_processor_id(), allbutme);
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if (!cpus_empty(allbutme))
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flat_send_IPI_mask(allbutme, vector);
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put_cpu();
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#endif
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}
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@ -149,10 +148,9 @@ static void physflat_send_IPI_mask(cpumask_t cpumask, int vector)
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static void physflat_send_IPI_allbutself(int vector)
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{
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cpumask_t allbutme = cpu_online_map;
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int me = get_cpu();
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cpu_clear(me, allbutme);
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cpu_clear(smp_processor_id(), allbutme);
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physflat_send_IPI_mask(allbutme, vector);
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put_cpu();
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}
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static void physflat_send_IPI_all(int vector)
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@ -15,11 +15,9 @@ static inline void __local_send_IPI_allbutself(int vector)
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{
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if (no_broadcast) {
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cpumask_t mask = cpu_online_map;
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int this_cpu = get_cpu();
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cpu_clear(this_cpu, mask);
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cpu_clear(smp_processor_id(), mask);
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send_IPI_mask(mask, vector);
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put_cpu();
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} else
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__send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
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}
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