4.4-stable review patch. If anyone has any objections, please let me know.
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From: James Smart jsmart2021@gmail.com
[ Upstream commit 0ef01a2d95fd62bb4f536e7ce4d5e8e74b97a244 ]
When running an mds diagnostic that passes frames with the switch, soft lockups are detected. The driver is in a CQE processing loop and has sufficient amount of traffic that it never exits the ring processing routine, thus the "lockup".
Cap the number of elements in the work processing routine to 64 elements. This ensures that the cpu will be given up and the handler reschedule to process additional items.
Signed-off-by: Dick Kennedy dick.kennedy@broadcom.com Signed-off-by: James Smart james.smart@broadcom.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/scsi/lpfc/lpfc_sli.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/drivers/scsi/lpfc/lpfc_sli.c +++ b/drivers/scsi/lpfc/lpfc_sli.c @@ -3485,6 +3485,7 @@ lpfc_sli_handle_slow_ring_event_s4(struc struct hbq_dmabuf *dmabuf; struct lpfc_cq_event *cq_event; unsigned long iflag; + int count = 0;
spin_lock_irqsave(&phba->hbalock, iflag); phba->hba_flag &= ~HBA_SP_QUEUE_EVT; @@ -3506,16 +3507,22 @@ lpfc_sli_handle_slow_ring_event_s4(struc if (irspiocbq) lpfc_sli_sp_handle_rspiocb(phba, pring, irspiocbq); + count++; break; case CQE_CODE_RECEIVE: case CQE_CODE_RECEIVE_V1: dmabuf = container_of(cq_event, struct hbq_dmabuf, cq_event); lpfc_sli4_handle_received_buffer(phba, dmabuf); + count++; break; default: break; } + + /* Limit the number of events to 64 to avoid soft lockups */ + if (count == 64) + break; } }