Messages in this thread Patch in this message | | | Date | Sun, 27 Nov 2005 02:05:58 -0800 (PST) | From | Zwane Mwaikambo <> | Subject | [PATCH] i386/x86_64: Remove preempt disable calls in lowlevel IPI calls |
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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>
arch/x86_64/kernel/genapic_cluster.c | 5 +---- arch/x86_64/kernel/genapic_flat.c | 10 ++++------ include/asm-i386/mach-default/mach_ipi.h | 4 +--- 3 files changed, 6 insertions(+), 13 deletions(-)
diff -r 2c0d5afbfb94 arch/x86_64/kernel/genapic_cluster.c --- a/arch/x86_64/kernel/genapic_cluster.c Fri Nov 25 17:42:19 2005 +++ b/arch/x86_64/kernel/genapic_cluster.c Sun Nov 27 00:10:53 2005 @@ -72,14 +72,11 @@ static void cluster_send_IPI_allbutself(int vector) { cpumask_t mask = cpu_online_map; - int me = get_cpu(); /* Ensure we are not preempted when we clear */ - cpu_clear(me, mask); + cpu_clear(smp_processor_id(), mask); if (!cpus_empty(mask)) cluster_send_IPI_mask(mask, vector); - - put_cpu(); } static void cluster_send_IPI_all(int vector) diff -r 2c0d5afbfb94 arch/x86_64/kernel/genapic_flat.c --- a/arch/x86_64/kernel/genapic_flat.c Fri Nov 25 17:42:19 2005 +++ b/arch/x86_64/kernel/genapic_flat.c Sun Nov 27 00:10:53 2005 @@ -83,12 +83,11 @@ __send_IPI_shortcut(APIC_DEST_ALLBUT, vector,APIC_DEST_LOGICAL); #else cpumask_t allbutme = cpu_online_map; - int me = get_cpu(); /* Ensure we are not preempted when we clear */ - cpu_clear(me, allbutme); + + cpu_clear(smp_processor_id(), allbutme); if (!cpus_empty(allbutme)) flat_send_IPI_mask(allbutme, vector); - put_cpu(); #endif } @@ -149,10 +148,9 @@ static void physflat_send_IPI_allbutself(int vector) { cpumask_t allbutme = cpu_online_map; - int me = get_cpu(); - cpu_clear(me, allbutme); + + cpu_clear(smp_processor_id(), allbutme); physflat_send_IPI_mask(allbutme, vector); - put_cpu(); } static void physflat_send_IPI_all(int vector) diff -r 2c0d5afbfb94 include/asm-i386/mach-default/mach_ipi.h --- a/include/asm-i386/mach-default/mach_ipi.h Fri Nov 25 17:42:19 2005 +++ b/include/asm-i386/mach-default/mach_ipi.h Sun Nov 27 00:10:53 2005 @@ -15,11 +15,9 @@ { if (no_broadcast) { cpumask_t mask = cpu_online_map; - int this_cpu = get_cpu(); - cpu_clear(this_cpu, mask); + cpu_clear(smp_processor_id(), mask); send_IPI_mask(mask, vector); - put_cpu(); } else __send_IPI_shortcut(APIC_DEST_ALLBUT, vector); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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