Commit d5705c4a authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

iscsi-target: Fix race with thread_pre_handler flush_signals + ISCSI_THREAD_SET_DIE 



This patch addresses an long standing race in iscsi_[rx,tx]_thread_pre_handler()
use of flush_signals(), and between iscsi_deallocate_extra_thread_sets() setting
ISCSI_THREAD_SET_DIE before calling kthread_stop().

It addresses the issue by both holding ts_state_lock before calling send_sig()
in iscsi_deallocate_extra_thread_sets(), as well as only calling flush_signals()
when ts->status != ISCSI_THREAD_SET_DIE within iscsi_[rx,tx]_thread_pre_handler()
code.

v2 changes:
  - Add explicit complete(&ts->[rx,tx]_start_comp); before kthread_stop() in
    iscsi_deallocate_extra_thread_sets()
  - Drop left-over send_sig() calls in iscsi_deallocate_extra_thread_sets()
  - Add kthread_should_stop() check in iscsi_signal_thread_pre_handler()

Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 0105c257

drivers/target/iscsi/iscsi_target_tq.c

+13 −6
Original line number Diff line number Diff line
@@ -189,16 +189,20 @@ static void iscsi_deallocate_extra_thread_sets(void) 


		spin_lock_bh(&ts->ts_state_lock);

		ts->status = ISCSI_THREAD_SET_DIE;

		spin_unlock_bh(&ts->ts_state_lock);



		if (ts->rx_thread) {

			send_sig(SIGINT, ts->rx_thread, 1);

			complete(&ts->rx_start_comp);

			spin_unlock_bh(&ts->ts_state_lock);

			kthread_stop(ts->rx_thread);

			spin_lock_bh(&ts->ts_state_lock);

		}

		if (ts->tx_thread) {

			send_sig(SIGINT, ts->tx_thread, 1);

			complete(&ts->tx_start_comp);

			spin_unlock_bh(&ts->ts_state_lock);

			kthread_stop(ts->tx_thread);

			spin_lock_bh(&ts->ts_state_lock);

		}

		spin_unlock_bh(&ts->ts_state_lock);

		/*

		 * Release this thread_id in the thread_set_bitmap

		 */
@@ -400,7 +404,8 @@ static void iscsi_check_to_add_additional_sets(void) 
static int iscsi_signal_thread_pre_handler(struct iscsi_thread_set *ts)

{

	spin_lock_bh(&ts->ts_state_lock);

	if ((ts->status == ISCSI_THREAD_SET_DIE) || signal_pending(current)) {

	if (ts->status == ISCSI_THREAD_SET_DIE || kthread_should_stop() ||

	    signal_pending(current)) {

		spin_unlock_bh(&ts->ts_state_lock);

		return -1;

	}
@@ -419,6 +424,7 @@ struct iscsi_conn *iscsi_rx_thread_pre_handler(struct iscsi_thread_set *ts) 
		goto sleep;

	}



	if (ts->status != ISCSI_THREAD_SET_DIE)

		flush_signals(current);



	if (ts->delay_inactive && (--ts->thread_count == 0)) {
@@ -472,6 +478,7 @@ struct iscsi_conn *iscsi_tx_thread_pre_handler(struct iscsi_thread_set *ts) 
		goto sleep;

	}



	if (ts->status != ISCSI_THREAD_SET_DIE)

		flush_signals(current);



	if (ts->delay_inactive && (--ts->thread_count == 0)) {

CRA Git | Maintained and supported by SUSTech CRA and CCSE