| From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 31/45] torture: Notice if an all-zero cpumask is passed inside a critical section | Date | Mon, 28 Apr 2014 17:25:19 -0700 |
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From: Iulia Manda <iulia.manda21@gmail.com>
In torture_shuffle_tasks function, the check if an all-zero mask can be passed to set_cpus_allowed_ptr() is redundant after clearing the shuffle_idle_cpu bit. If the mask had more than one bit set, after clearing a bit it has at least one bit set. If the mask had only one bit set, a check is made at the beginning, where the function returns, as there is no need to shuffle only one cpu.
Also, this code is executed inside a critical section, delimited by get_online_cpus(), and put_online_cpus(), preventing CPUs from leaving between the check of num_online_cpus and the calls to set_cpus_allowed_ptr() function.
Signed-off-by: Iulia Manda <iulia.manda21@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- kernel/torture.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/kernel/torture.c b/kernel/torture.c index bd768effba9a..c1d57e83e8fe 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -335,13 +335,8 @@ static void torture_shuffle_tasks(void) shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask); if (shuffle_idle_cpu >= nr_cpu_ids) shuffle_idle_cpu = -1; - if (shuffle_idle_cpu != -1) { + else cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask); - if (cpumask_empty(shuffle_tmp_mask)) { - put_online_cpus(); - return; - } - } mutex_lock(&shuffle_task_mutex); list_for_each_entry(stp, &shuffle_task_list, st_l) -- 1.8.1.5
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