Commit 8be3e5b0 authored by Selvin Xavier's avatar Selvin Xavier Committed by Jason Gunthorpe
Browse files

RDMA/bnxt_re: Avoid CPU lockups due fifo occupancy check loop 

Driver waits indefinitely for the fifo occupancy to go below a threshold
as soon as the pacing interrupt is received. This can cause soft lockup on
one of the processors, if the rate of DB is very high.

Add a loop count for FPGA and exit the __wait_for_fifo_occupancy_below_th
if the loop is taking more time. Pacing will be continuing until the
occupancy is below the threshold. This is ensured by the checks in
bnxt_re_pacing_timer_exp and further scheduling the work for pacing based
on the fifo occupancy.

Fixes: 2ad4e630 ("RDMA/bnxt_re: Implement doorbell pacing algorithm")
Link: https://patch.msgid.link/r/1728373302-19530-7-git-send-email-selvin.xavier@broadcom.com


Reviewed-by: default avatarKalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: default avatarChandramohan Akula <chandramohan.akula@broadcom.com>
Signed-off-by: default avatarSelvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 0ba9294d

drivers/infiniband/hw/bnxt_re/main.c

+9 −0
Original line number Diff line number Diff line
@@ -534,6 +534,7 @@ static bool is_dbr_fifo_full(struct bnxt_re_dev *rdev) 
static void __wait_for_fifo_occupancy_below_th(struct bnxt_re_dev *rdev)

{

	struct bnxt_qplib_db_pacing_data *pacing_data = rdev->qplib_res.pacing_data;

	u32 retry_fifo_check = 1000;

	u32 fifo_occup;



	/* loop shouldn't run infintely as the occupancy usually goes
@@ -547,6 +548,14 @@ static void __wait_for_fifo_occupancy_below_th(struct bnxt_re_dev *rdev) 


		if (fifo_occup < pacing_data->pacing_th)

			break;

		if (!retry_fifo_check--) {

			dev_info_once(rdev_to_dev(rdev),

				      "%s: fifo_occup = 0x%xfifo_max_depth = 0x%x pacing_th = 0x%x\n",

				      __func__, fifo_occup, pacing_data->fifo_max_depth,

					pacing_data->pacing_th);

			break;

		}



	}

}