Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Mon, 14 Nov 2016 00:14:20 +0000 | Subject | [PATCH 3.16 093/346] target: Fix missing complete during ABORT_TASK + CMD_T_FABRIC_STOP |
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3.16.39-rc1 review patch. If anyone has any objections, please let me know.
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From: Nicholas Bellinger <nab@linux-iscsi.org>
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> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/target/target_core_transport.c | 6 ------ 1 file changed, 6 deletions(-)
--- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -2455,12 +2455,6 @@ static void target_release_cmd_kref(stru struct se_session *se_sess = se_cmd->se_sess; bool fabric_stop; - if (list_empty(&se_cmd->se_cmd_list)) { - spin_unlock(&se_sess->sess_cmd_lock); - 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);
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