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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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10
arch/mips/kernel/mips-mt-fpaff.c
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@ -58,13 +58,13 @@ asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
return -EFAULT;
lock_cpu_hotplug();
get_online_cpus();
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
if (!p) {
read_unlock(&tasklist_lock);
unlock_cpu_hotplug();
put_online_cpus();
return -ESRCH;
}
@ -106,7 +106,7 @@ asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
out_unlock:
put_task_struct(p);
unlock_cpu_hotplug();
put_online_cpus();
return retval;
}
@ -125,7 +125,7 @@ asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
if (len < real_len)
return -EINVAL;
lock_cpu_hotplug();
get_online_cpus();
read_lock(&tasklist_lock);
retval = -ESRCH;
@ -140,7 +140,7 @@ asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
out_unlock:
read_unlock(&tasklist_lock);
unlock_cpu_hotplug();
put_online_cpus();
if (retval)
return retval;
if (copy_to_user(user_mask_ptr, &mask, real_len))