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target: fix list walking in transport_free_dev_tasks 

list_for_each_entry_safe only protects against deletions from the list,
but not against any concurrent modifications.  Given that we drop
t_state_lock inside the loop it is not safe in transport_free_dev_tasks.

Instead of use a local dispose_list that we move all tasks that are
to be deleted to.  This is safe because we never do list_emptry checks
on t_list to check if a command is on the list anywhere.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Christoph Hellwig 2011-10-17 13:56:45 -04:00 committed by Nicholas Bellinger
parent b7b8bef7f8
commit 0c2cfe5fe7
1 changed files with 8 additions and 5 deletions
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13
drivers/target/target_core_transport.c
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@ -3585,23 +3585,26 @@ static void transport_free_dev_tasks(struct se_cmd *cmd)
{
struct se_task *task, *task_tmp;
unsigned long flags;
LIST_HEAD(dispose_list);
spin_lock_irqsave(&cmd->t_state_lock, flags);
list_for_each_entry_safe(task, task_tmp,
&cmd->t_task_list, t_list) {
if (task->task_flags & TF_ACTIVE)
continue;
if (!(task->task_flags & TF_ACTIVE))
list_move_tail(&task->t_list, &dispose_list);
}
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
while (!list_empty(&dispose_list)) {
task = list_first_entry(&dispose_list, struct se_task, t_list);
kfree(task->task_sg_bidi);
kfree(task->task_sg);
list_del(&task->t_list);
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
cmd->se_dev->transport->free_task(task);
spin_lock_irqsave(&cmd->t_state_lock, flags);
}
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
}
static inline void transport_free_sgl(struct scatterlist *sgl, int nents)