Commit 2c7da8e6 authored by Gerd Rausch's avatar Gerd Rausch Committed by David S. Miller
Browse files

net/rds: Give fr_state a chance to transition to FRMR_IS_FREE 



In the context of FRMR (ib_frmr.c):

Memory regions make it onto the "clean_list" via "rds_ib_flush_mr_pool",
after the memory region has been posted for invalidation via
"rds_ib_post_inv".

At that point in time, "fr_state" may still be in state "FRMR_IS_INUSE",
since the only place where "fr_state" transitions to "FRMR_IS_FREE"
is in "rds_ib_mr_cqe_handler", which is triggered by a tasklet.

So in case we notice that "fr_state != FRMR_IS_FREE" (see below),
we wait for "fr_inv_done" to trigger with a maximum of 10msec.
Then we check again, and only put the memory region onto the drop_list
(via "rds_ib_free_frmr") in case the situation remains unchanged.

This avoids the problem of memory-regions bouncing between "clean_list"
and "drop_list" before they even have a chance to be properly invalidated.

Signed-off-by: default avatarGerd Rausch <gerd.rausch@oracle.com>
Acked-by: default avatarSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f11fe1da

net/rds/ib_frmr.c

+26 −1
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ static struct rds_ib_mr *rds_ib_alloc_frmr(struct rds_ib_device *rds_ibdev, 
		pool->max_items_soft = pool->max_items;



	frmr->fr_state = FRMR_IS_FREE;

	init_waitqueue_head(&frmr->fr_inv_done);

	return ibmr;



out_no_cigar:
@@ -285,6 +286,7 @@ void rds_ib_mr_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc) 
	if (frmr->fr_inv) {

		frmr->fr_state = FRMR_IS_FREE;

		frmr->fr_inv = false;

		wake_up(&frmr->fr_inv_done);

	}



	atomic_inc(&ic->i_fastreg_wrs);
@@ -345,8 +347,31 @@ struct rds_ib_mr *rds_ib_reg_frmr(struct rds_ib_device *rds_ibdev, 
	}



	do {

		if (ibmr)

		if (ibmr) {

			/* Memory regions make it onto the "clean_list" via

			 * "rds_ib_flush_mr_pool", after the memory region has

			 * been posted for invalidation via "rds_ib_post_inv".

			 *

			 * At that point in time, "fr_state" may still be

			 * in state "FRMR_IS_INUSE", since the only place where

			 * "fr_state" transitions to "FRMR_IS_FREE" is in

			 * is in "rds_ib_mr_cqe_handler", which is

			 * triggered by a tasklet.

			 *

			 * So we wait for "fr_inv_done" to trigger

			 * and only put memory regions onto the drop_list

			 * that failed (i.e. not marked "FRMR_IS_FREE").

			 *

			 * This avoids the problem of memory-regions bouncing

			 * between "clean_list" and "drop_list" before they

			 * even have a chance to be properly invalidated.

			 */

			frmr = &ibmr->u.frmr;

			wait_event(frmr->fr_inv_done, frmr->fr_state != FRMR_IS_INUSE);

			if (frmr->fr_state == FRMR_IS_FREE)

				break;

			rds_ib_free_frmr(ibmr, true);

		}

		ibmr = rds_ib_alloc_frmr(rds_ibdev, nents);

		if (IS_ERR(ibmr))

			return ibmr;

net/rds/ib_mr.h

+1 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ struct rds_ib_frmr { 
	struct ib_mr		*mr;

	enum rds_ib_fr_state	fr_state;

	bool			fr_inv;

	wait_queue_head_t	fr_inv_done;

	struct ib_send_wr	fr_wr;

	unsigned int		dma_npages;

	unsigned int		sg_byte_len;

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