ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()
After we acquire the sma->sem_perm lock in exit_sem(), we are protected against a racing IPC_RMID operation. Also at that point, we are the last user of sem_undo_list. Therefore it isn't required that we acquire or use ulp->lock. Signed-off-by: Herton R. Krzesinski <herton@redhat.com> Acked-by: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Rafael Aquini <aquini@redhat.com> CC: Aristeu Rozanski <aris@redhat.com> Cc: David Jeffery <djeffery@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 changed files with 4 additions and 2 deletions
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@ -2123,9 +2123,11 @@ void exit_sem(struct task_struct *tsk)
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ipc_assert_locked_object(&sma->sem_perm);
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ipc_assert_locked_object(&sma->sem_perm);
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list_del(&un->list_id);
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list_del(&un->list_id);
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spin_lock(&ulp->lock);
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/* we are the last process using this ulp, acquiring ulp->lock
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* isn't required. Besides that, we are also protected against
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* IPC_RMID as we hold sma->sem_perm lock now
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*/
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list_del_rcu(&un->list_proc);
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list_del_rcu(&un->list_proc);
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spin_unlock(&ulp->lock);
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/* perform adjustments registered in un */
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/* perform adjustments registered in un */
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for (i = 0; i < sma->sem_nsems; i++) {
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for (i = 0; i < sma->sem_nsems; i++) {
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