From d5705c4ab5035be618a34c95505727acac2e70ec Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Fri, 6 Sep 2013 20:46:50 -0700 Subject: [PATCH] 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: Nicholas Bellinger --- drivers/target/iscsi/iscsi_target_tq.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target_tq.c b/drivers/target/iscsi/iscsi_target_tq.c index 81289520f96b..1a5bbec03f3e 100644 --- a/drivers/target/iscsi/iscsi_target_tq.c +++ b/drivers/target/iscsi/iscsi_target_tq.c @@ -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; } @@ -419,7 +424,8 @@ struct iscsi_conn *iscsi_rx_thread_pre_handler(struct iscsi_thread_set *ts) goto sleep; } - flush_signals(current); + if (ts->status != ISCSI_THREAD_SET_DIE) + flush_signals(current); if (ts->delay_inactive && (--ts->thread_count == 0)) { spin_unlock_bh(&ts->ts_state_lock); @@ -472,7 +478,8 @@ struct iscsi_conn *iscsi_tx_thread_pre_handler(struct iscsi_thread_set *ts) goto sleep; } - flush_signals(current); + if (ts->status != ISCSI_THREAD_SET_DIE) + flush_signals(current); if (ts->delay_inactive && (--ts->thread_count == 0)) { spin_unlock_bh(&ts->ts_state_lock); -- GitLab