[PATCH] i386: Dont use IPI broadcast when using cpu hotplug.
This patch introduces a startup parameter no_broadcast. When we enable
CONFIG_HOTPLUG_CPU, we dont want to use broadcast shortcut as it has ill
effects on a offline cpu. If we issue broadcast, the IPI is also delivered
to offline cpus, or partially up cpu causing stale IPI's to be handled,
which is a problem and can cause undesirable effects.
Introduces a new startup cmdline option no_ipi_broadcast, that can be
switched at cmdline if necessary.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Acked-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-i386/mach-default/mach_ipi.h b/include/asm-i386/mach-default/mach_ipi.h
index 6f2b17a..cc756a6 100644
--- a/include/asm-i386/mach-default/mach_ipi.h
+++ b/include/asm-i386/mach-default/mach_ipi.h
@@ -4,11 +4,34 @@
void send_IPI_mask_bitmask(cpumask_t mask, int vector);
void __send_IPI_shortcut(unsigned int shortcut, int vector);
+extern int no_broadcast;
+
static inline void send_IPI_mask(cpumask_t mask, int vector)
{
send_IPI_mask_bitmask(mask, vector);
}
+static inline void __local_send_IPI_allbutself(int vector)
+{
+ if (no_broadcast) {
+ cpumask_t mask = cpu_online_map;
+ int this_cpu = get_cpu();
+
+ cpu_clear(this_cpu, mask);
+ send_IPI_mask(mask, vector);
+ put_cpu();
+ } else
+ __send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
+}
+
+static inline void __local_send_IPI_all(int vector)
+{
+ if (no_broadcast)
+ send_IPI_mask(cpu_online_map, vector);
+ else
+ __send_IPI_shortcut(APIC_DEST_ALLINC, vector);
+}
+
static inline void send_IPI_allbutself(int vector)
{
/*
@@ -18,13 +41,13 @@
if (!(num_online_cpus() > 1))
return;
- __send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
+ __local_send_IPI_allbutself(vector);
return;
}
static inline void send_IPI_all(int vector)
{
- __send_IPI_shortcut(APIC_DEST_ALLINC, vector);
+ __local_send_IPI_all(vector);
}
#endif /* __ASM_MACH_IPI_H */