Messages in this thread | | | Date | Sat, 22 Nov 2008 11:01:01 +0800 | From | Lai Jiangshan <> | Subject | Re: [PATCH] cpuset: rcu_read_lock() to protect task_cs() even we don't dereference to task_cs()'s return value |
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Paul Menage wrote: > On Fri, Nov 21, 2008 at 11:05 AM, Paul Menage <menage@google.com> wrote: >> Wouldn't this be fixed by your patch that adds an rcu_read_lock() to >> task_subsys_state() ? >> > > Sorry, your other patch actually adds the rcu_read_lock() to > task_cgroup(). But adding an rcu_read_lock() to task_subsys_state() > would also help here.
Adding an rcu_read_lock() to task_subsys_state() also help here. But task_subsys_state() is used in fast path.
If we add an implicit rcu_read_lock() in task_subsys_state(), we still need rcu_read_lock()/task_lock() for using it, so it's redundant rcu_read_lock(), and slower the fast path a little.
Lai.
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