Commit aff7bfed authored by D. Wythe's avatar D. Wythe Committed by David S. Miller
Browse files

net/smc: replace mutex rmbs_lock and sndbufs_lock with rw_semaphore 



It's clear that rmbs_lock and sndbufs_lock are aims to protect the
rmbs list or the sndbufs list.

During connection establieshment, smc_buf_get_slot() will always
be invoked, and it only performs read semantics in rmbs list and
sndbufs list.

Based on the above considerations, we replace mutex with rw_semaphore.
Only smc_buf_get_slot() use down_read() to allow smc_buf_get_slot()
run concurrently, other part use down_write() to keep exclusive
semantics.

Signed-off-by: default avatarD. Wythe <alibuda@linux.alibaba.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4da68744

net/smc/smc_core.c

+28 −27
Original line number Diff line number Diff line
@@ -854,8 +854,8 @@ static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini) 
	lgr->freeing = 0;

	lgr->vlan_id = ini->vlan_id;

	refcount_set(&lgr->refcnt, 1); /* set lgr refcnt to 1 */

	mutex_init(&lgr->sndbufs_lock);

	mutex_init(&lgr->rmbs_lock);

	init_rwsem(&lgr->sndbufs_lock);

	init_rwsem(&lgr->rmbs_lock);

	rwlock_init(&lgr->conns_lock);

	for (i = 0; i < SMC_RMBE_SIZES; i++) {

		INIT_LIST_HEAD(&lgr->sndbufs[i]);
@@ -1098,7 +1098,7 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr, 
static void smcr_buf_unuse(struct smc_buf_desc *buf_desc, bool is_rmb,

			   struct smc_link_group *lgr)

{

	struct mutex *lock;	/* lock buffer list */

	struct rw_semaphore *lock;	/* lock buffer list */

	int rc;



	if (is_rmb && buf_desc->is_conf_rkey && !list_empty(&lgr->list)) {
@@ -1118,9 +1118,9 @@ static void smcr_buf_unuse(struct smc_buf_desc *buf_desc, bool is_rmb, 
		/* buf registration failed, reuse not possible */

		lock = is_rmb ? &lgr->rmbs_lock :

				&lgr->sndbufs_lock;

		mutex_lock(lock);

		down_write(lock);

		list_del(&buf_desc->list);

		mutex_unlock(lock);

		up_write(lock);



		smc_buf_free(lgr, is_rmb, buf_desc);

	} else {
@@ -1224,15 +1224,16 @@ static void smcr_buf_unmap_lgr(struct smc_link *lnk) 
	int i;



	for (i = 0; i < SMC_RMBE_SIZES; i++) {

		mutex_lock(&lgr->rmbs_lock);

		down_write(&lgr->rmbs_lock);

		list_for_each_entry_safe(buf_desc, bf, &lgr->rmbs[i], list)

			smcr_buf_unmap_link(buf_desc, true, lnk);

		mutex_unlock(&lgr->rmbs_lock);

		mutex_lock(&lgr->sndbufs_lock);

		up_write(&lgr->rmbs_lock);



		down_write(&lgr->sndbufs_lock);

		list_for_each_entry_safe(buf_desc, bf, &lgr->sndbufs[i],

					 list)

			smcr_buf_unmap_link(buf_desc, false, lnk);

		mutex_unlock(&lgr->sndbufs_lock);

		up_write(&lgr->sndbufs_lock);

	}

}
@@ -1990,19 +1991,19 @@ int smc_uncompress_bufsize(u8 compressed) 
 * buffer size; if not available, return NULL

 */

static struct smc_buf_desc *smc_buf_get_slot(int compressed_bufsize,

					     struct mutex *lock,

					     struct rw_semaphore *lock,

					     struct list_head *buf_list)

{

	struct smc_buf_desc *buf_slot;



	mutex_lock(lock);

	down_read(lock);

	list_for_each_entry(buf_slot, buf_list, list) {

		if (cmpxchg(&buf_slot->used, 0, 1) == 0) {

			mutex_unlock(lock);

			up_read(lock);

			return buf_slot;

		}

	}

	mutex_unlock(lock);

	up_read(lock);

	return NULL;

}
@@ -2111,13 +2112,13 @@ int smcr_link_reg_buf(struct smc_link *link, struct smc_buf_desc *buf_desc) 
	return 0;

}



static int _smcr_buf_map_lgr(struct smc_link *lnk, struct mutex *lock,

static int _smcr_buf_map_lgr(struct smc_link *lnk, struct rw_semaphore *lock,

			     struct list_head *lst, bool is_rmb)

{

	struct smc_buf_desc *buf_desc, *bf;

	int rc = 0;



	mutex_lock(lock);

	down_write(lock);

	list_for_each_entry_safe(buf_desc, bf, lst, list) {

		if (!buf_desc->used)

			continue;
@@ -2126,7 +2127,7 @@ static int _smcr_buf_map_lgr(struct smc_link *lnk, struct mutex *lock, 
			goto out;

	}

out:

	mutex_unlock(lock);

	up_write(lock);

	return rc;

}
@@ -2159,37 +2160,37 @@ int smcr_buf_reg_lgr(struct smc_link *lnk) 
	int i, rc = 0;



	/* reg all RMBs for a new link */

	mutex_lock(&lgr->rmbs_lock);

	down_write(&lgr->rmbs_lock);

	for (i = 0; i < SMC_RMBE_SIZES; i++) {

		list_for_each_entry_safe(buf_desc, bf, &lgr->rmbs[i], list) {

			if (!buf_desc->used)

				continue;

			rc = smcr_link_reg_buf(lnk, buf_desc);

			if (rc) {

				mutex_unlock(&lgr->rmbs_lock);

				up_write(&lgr->rmbs_lock);

				return rc;

			}

		}

	}

	mutex_unlock(&lgr->rmbs_lock);

	up_write(&lgr->rmbs_lock);



	if (lgr->buf_type == SMCR_PHYS_CONT_BUFS)

		return rc;



	/* reg all vzalloced sndbufs for a new link */

	mutex_lock(&lgr->sndbufs_lock);

	down_write(&lgr->sndbufs_lock);

	for (i = 0; i < SMC_RMBE_SIZES; i++) {

		list_for_each_entry_safe(buf_desc, bf, &lgr->sndbufs[i], list) {

			if (!buf_desc->used || !buf_desc->is_vm)

				continue;

			rc = smcr_link_reg_buf(lnk, buf_desc);

			if (rc) {

				mutex_unlock(&lgr->sndbufs_lock);

				up_write(&lgr->sndbufs_lock);

				return rc;

			}

		}

	}

	mutex_unlock(&lgr->sndbufs_lock);

	up_write(&lgr->sndbufs_lock);

	return rc;

}
@@ -2309,8 +2310,8 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb) 
	struct smc_link_group *lgr = conn->lgr;

	struct list_head *buf_list;

	int bufsize, bufsize_short;

	struct rw_semaphore *lock;	/* lock buffer list */

	bool is_dgraded = false;

	struct mutex *lock;	/* lock buffer list */

	int sk_buf_size;



	if (is_rmb)
@@ -2358,9 +2359,9 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb) 
		SMC_STAT_RMB_ALLOC(smc, is_smcd, is_rmb);

		SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, bufsize);

		buf_desc->used = 1;

		mutex_lock(lock);

		down_write(lock);

		list_add(&buf_desc->list, buf_list);

		mutex_unlock(lock);

		up_write(lock);

		break; /* found */

	}
@@ -2434,9 +2435,9 @@ int smc_buf_create(struct smc_sock *smc, bool is_smcd) 
	/* create rmb */

	rc = __smc_buf_create(smc, is_smcd, true);

	if (rc) {

		mutex_lock(&smc->conn.lgr->sndbufs_lock);

		down_write(&smc->conn.lgr->sndbufs_lock);

		list_del(&smc->conn.sndbuf_desc->list);

		mutex_unlock(&smc->conn.lgr->sndbufs_lock);

		up_write(&smc->conn.lgr->sndbufs_lock);

		smc_buf_free(smc->conn.lgr, false, smc->conn.sndbuf_desc);

		smc->conn.sndbuf_desc = NULL;

	}

net/smc/smc_core.h

+2 −2
Original line number Diff line number Diff line
@@ -252,9 +252,9 @@ struct smc_link_group { 
	unsigned short		vlan_id;	/* vlan id of link group */



	struct list_head	sndbufs[SMC_RMBE_SIZES];/* tx buffers */

	struct mutex		sndbufs_lock;	/* protects tx buffers */

	struct rw_semaphore	sndbufs_lock;	/* protects tx buffers */

	struct list_head	rmbs[SMC_RMBE_SIZES];	/* rx buffers */

	struct mutex		rmbs_lock;	/* protects rx buffers */

	struct rw_semaphore	rmbs_lock;	/* protects rx buffers */



	u8			id[SMC_LGR_ID_SIZE];	/* unique lgr id */

	struct delayed_work	free_work;	/* delayed freeing of an lgr */

net/smc/smc_llc.c

+8 −8
Original line number Diff line number Diff line
@@ -608,7 +608,7 @@ static int smc_llc_fill_ext_v2(struct smc_llc_msg_add_link_v2_ext *ext, 


	prim_lnk_idx = link->link_idx;

	lnk_idx = link_new->link_idx;

	mutex_lock(&lgr->rmbs_lock);

	down_write(&lgr->rmbs_lock);

	ext->num_rkeys = lgr->conns_num;

	if (!ext->num_rkeys)

		goto out;
@@ -628,7 +628,7 @@ static int smc_llc_fill_ext_v2(struct smc_llc_msg_add_link_v2_ext *ext, 
	}

	len += i * sizeof(ext->rt[0]);

out:

	mutex_unlock(&lgr->rmbs_lock);

	up_write(&lgr->rmbs_lock);

	return len;

}
@@ -889,7 +889,7 @@ static int smc_llc_cli_rkey_exchange(struct smc_link *link, 
	int rc = 0;

	int i;



	mutex_lock(&lgr->rmbs_lock);

	down_write(&lgr->rmbs_lock);

	num_rkeys_send = lgr->conns_num;

	buf_pos = smc_llc_get_first_rmb(lgr, &buf_lst);

	do {
@@ -916,7 +916,7 @@ static int smc_llc_cli_rkey_exchange(struct smc_link *link, 
			break;

	} while (num_rkeys_send || num_rkeys_recv);



	mutex_unlock(&lgr->rmbs_lock);

	up_write(&lgr->rmbs_lock);

	return rc;

}
@@ -999,14 +999,14 @@ static void smc_llc_save_add_link_rkeys(struct smc_link *link, 
	ext = (struct smc_llc_msg_add_link_v2_ext *)((u8 *)lgr->wr_rx_buf_v2 +

						     SMC_WR_TX_SIZE);

	max = min_t(u8, ext->num_rkeys, SMC_LLC_RKEYS_PER_MSG_V2);

	mutex_lock(&lgr->rmbs_lock);

	down_write(&lgr->rmbs_lock);

	for (i = 0; i < max; i++) {

		smc_rtoken_set(lgr, link->link_idx, link_new->link_idx,

			       ext->rt[i].rmb_key,

			       ext->rt[i].rmb_vaddr_new,

			       ext->rt[i].rmb_key_new);

	}

	mutex_unlock(&lgr->rmbs_lock);

	up_write(&lgr->rmbs_lock);

}



static void smc_llc_save_add_link_info(struct smc_link *link,
@@ -1313,7 +1313,7 @@ static int smc_llc_srv_rkey_exchange(struct smc_link *link, 
	int rc = 0;

	int i;



	mutex_lock(&lgr->rmbs_lock);

	down_write(&lgr->rmbs_lock);

	num_rkeys_send = lgr->conns_num;

	buf_pos = smc_llc_get_first_rmb(lgr, &buf_lst);

	do {
@@ -1338,7 +1338,7 @@ static int smc_llc_srv_rkey_exchange(struct smc_link *link, 
		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);

	} while (num_rkeys_send || num_rkeys_recv);

out:

	mutex_unlock(&lgr->rmbs_lock);

	up_write(&lgr->rmbs_lock);

	return rc;

}