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cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()

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Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Gautham R Shenoy
2008-01-25 21:08:02 +01:00
committed by Ingo Molnar
parent d221938c04
commit 86ef5c9a8e
15 changed files with 62 additions and 61 deletions
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4
kernel/sched.c
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@@ -7152,7 +7152,7 @@ static int load_balance_monitor(void *unused)
int i, cpu, balanced = 1;
/* Prevent cpus going down or coming up */
lock_cpu_hotplug();
get_online_cpus();
/* lockout changes to doms_cur[] array */
lock_doms_cur();
/*
@@ -7186,7 +7186,7 @@ static int load_balance_monitor(void *unused)
rcu_read_unlock();
unlock_doms_cur();
unlock_cpu_hotplug();
put_online_cpus();
if (!balanced)
timeout = sysctl_sched_min_bal_int_shares;