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authorNicholas Bellinger <nab@linux-iscsi.org>2016-05-25 12:25:04 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-08-20 18:09:26 +0200
commit60ba156dda2c11ff7a44d78ec64abd21b9813115 (patch)
tree153237069818a29c034c0890b3c158cea424357f
parent6492c1c5b95658bc070d5d231bc32568b84b49bb (diff)
downloadlwn-60ba156dda2c11ff7a44d78ec64abd21b9813115.tar.gz
lwn-60ba156dda2c11ff7a44d78ec64abd21b9813115.zip
target: Fix missing complete during ABORT_TASK + CMD_T_FABRIC_STOP
commit 5e2c956b8aa24d4f33ff7afef92d409eed164746 upstream. During transport_generic_free_cmd() with a concurrent TMR ABORT_TASK and shutdown CMD_T_FABRIC_STOP bit set, the caller will be blocked on se_cmd->cmd_wait_stop completion until the final kref_put() -> target_release_cmd_kref() has been invoked to call complete(). However, when ABORT_TASK is completed with FUNCTION_COMPLETE in core_tmr_abort_task(), the aborted se_cmd will have already been removed from se_sess->sess_cmd_list via list_del_init(). This results in target_release_cmd_kref() hitting the legacy list_empty() == true check, invoking ->release_cmd() but skipping complete() to wakeup se_cmd->cmd_wait_stop blocked earlier in transport_generic_free_cmd() code. To address this bug, it's safe to go ahead and drop the original list_empty() check so that fabric_stop invokes the complete() as expected, since list_del_init() can safely be used on a empty list. Cc: Mike Christie <mchristi@redhat.com> Cc: Quinn Tran <quinn.tran@qlogic.com> Cc: Himanshu Madhani <himanshu.madhani@qlogic.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Tested-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/target/target_core_transport.c6
1 files changed, 0 insertions, 6 deletions
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 7f4cdc82234b..93fb7c0dfa3c 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2541,12 +2541,6 @@ static void target_release_cmd_kref(struct kref *kref)
bool fabric_stop;
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
- if (list_empty(&se_cmd->se_cmd_list)) {
- spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
- target_free_cmd_mem(se_cmd);
- se_cmd->se_tfo->release_cmd(se_cmd);
- return;
- }
spin_lock(&se_cmd->t_state_lock);
fabric_stop = (se_cmd->transport_state & CMD_T_FABRIC_STOP);