diff mbox series

[net-next,v5,07/10] net/smc: llc_conf_mutex refactor, replace it with rw_semaphore

Message ID 1669218890-115854-8-git-send-email-alibuda@linux.alibaba.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series optimize the parallelism of SMC-R connections | expand

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Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/cc_maintainers warning 2 maintainers not CCed: pabeni@redhat.com edumazet@google.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 188 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

D. Wythe Nov. 23, 2022, 3:54 p.m. UTC 
From: "D. Wythe" <alibuda@linux.alibaba.com>

llc_conf_mutex was used to protect links and link related configurations
in the same link group, for example, add or delete links. However,
in most cases, the protected critical area has only read semantics and
with no write semantics at all, such as obtaining a usable link or an
available rmb_desc.

This patch do simply code refactoring, replace mutex with rw_semaphore,
replace mutex_lock with down_write and replace mutex_unlock with
up_write.

Theoretically, this replacement is equivalent, but after this patch,
we can distinguish lock granularity according to different semantics
of critical areas.

Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
 net/smc/af_smc.c   | 12 ++++++------
 net/smc/smc_core.c | 20 ++++++++++----------
 net/smc/smc_core.h |  2 +-
 net/smc/smc_llc.c  | 18 +++++++++---------
 4 files changed, 26 insertions(+), 26 deletions(-)
diff mbox series

Patch

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 7587760..338ae3f 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -495,7 +495,7 @@  static int smcr_lgr_reg_sndbufs(struct smc_link *link,
 		return -EINVAL;
 
 	/* protect against parallel smcr_link_reg_buf() */
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
 		if (!smc_link_active(&lgr->lnk[i]))
 			continue;
@@ -503,7 +503,7 @@  static int smcr_lgr_reg_sndbufs(struct smc_link *link,
 		if (rc)
 			break;
 	}
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 	return rc;
 }
 
@@ -520,7 +520,7 @@  static int smcr_lgr_reg_rmbs(struct smc_link *link,
 	/* protect against parallel smc_llc_cli_rkey_exchange() and
 	 * parallel smcr_link_reg_buf()
 	 */
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
 		if (!smc_link_active(&lgr->lnk[i]))
 			continue;
@@ -537,7 +537,7 @@  static int smcr_lgr_reg_rmbs(struct smc_link *link,
 	}
 	rmb_desc->is_conf_rkey = true;
 out:
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 	smc_llc_flow_stop(lgr, &lgr->llc_flow_lcl);
 	return rc;
 }
@@ -1818,10 +1818,10 @@  static int smcr_serv_conf_first_link(struct smc_sock *smc)
 	smc_llc_link_active(link);
 	smcr_lgr_set_type(link->lgr, SMC_LGR_SINGLE);
 
-	mutex_lock(&link->lgr->llc_conf_mutex);
+	down_write(&link->lgr->llc_conf_mutex);
 	/* initial contact - try to establish second link */
 	smc_llc_srv_add_link(link, NULL);
-	mutex_unlock(&link->lgr->llc_conf_mutex);
+	up_write(&link->lgr->llc_conf_mutex);
 	return 0;
 }
 
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 612ded2..10a90bf 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1388,10 +1388,10 @@  static void smcr_buf_unuse(struct smc_buf_desc *buf_desc, bool is_rmb,
 		rc = smc_llc_flow_initiate(lgr, SMC_LLC_FLOW_RKEY);
 		if (!rc) {
 			/* protect against smc_llc_cli_rkey_exchange() */
-			mutex_lock(&lgr->llc_conf_mutex);
+			down_write(&lgr->llc_conf_mutex);
 			smc_llc_do_delete_rkey(lgr, buf_desc);
 			buf_desc->is_conf_rkey = false;
-			mutex_unlock(&lgr->llc_conf_mutex);
+			up_write(&lgr->llc_conf_mutex);
 			smc_llc_flow_stop(lgr, &lgr->llc_flow_lcl);
 		}
 	}
@@ -1661,12 +1661,12 @@  static void smc_lgr_free(struct smc_link_group *lgr)
 	int i;
 
 	if (!lgr->is_smcd) {
-		mutex_lock(&lgr->llc_conf_mutex);
+		down_write(&lgr->llc_conf_mutex);
 		for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
 			if (lgr->lnk[i].state != SMC_LNK_UNUSED)
 				smcr_link_clear(&lgr->lnk[i], false);
 		}
-		mutex_unlock(&lgr->llc_conf_mutex);
+		up_write(&lgr->llc_conf_mutex);
 		smc_llc_lgr_clear(lgr);
 	}
 
@@ -1980,12 +1980,12 @@  static void smcr_link_down(struct smc_link *lnk)
 	} else {
 		if (lgr->llc_flow_lcl.type != SMC_LLC_FLOW_NONE) {
 			/* another llc task is ongoing */
-			mutex_unlock(&lgr->llc_conf_mutex);
+			up_write(&lgr->llc_conf_mutex);
 			wait_event_timeout(lgr->llc_flow_waiter,
 				(list_empty(&lgr->list) ||
 				 lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
 				SMC_LLC_WAIT_TIME);
-			mutex_lock(&lgr->llc_conf_mutex);
+			down_write(&lgr->llc_conf_mutex);
 		}
 		if (!list_empty(&lgr->list)) {
 			smc_llc_send_delete_link(to_lnk, del_link_id,
@@ -2045,9 +2045,9 @@  static void smc_link_down_work(struct work_struct *work)
 	if (list_empty(&lgr->list))
 		return;
 	wake_up_all(&lgr->llc_msg_waiter);
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	smcr_link_down(link);
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 }
 
 static int smc_vlan_by_tcpsk_walk(struct net_device *lower_dev,
@@ -2645,7 +2645,7 @@  static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
 	int i, rc = 0, cnt = 0;
 
 	/* protect against parallel link reconfiguration */
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
 		struct smc_link *lnk = &lgr->lnk[i];
 
@@ -2658,7 +2658,7 @@  static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
 		cnt++;
 	}
 out:
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 	if (!rc && !cnt)
 		rc = -EINVAL;
 	return rc;
diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
index ec32524..3bbf159 100644
--- a/net/smc/smc_core.h
+++ b/net/smc/smc_core.h
@@ -307,7 +307,7 @@  struct smc_link_group {
 						/* queue for llc events */
 			spinlock_t		llc_event_q_lock;
 						/* protects llc_event_q */
-			struct mutex		llc_conf_mutex;
+			struct rw_semaphore	llc_conf_mutex;
 						/* protects lgr reconfig. */
 			struct work_struct	llc_add_link_work;
 			struct work_struct	llc_del_link_work;
diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
index 569d1a2..4426642 100644
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -1238,12 +1238,12 @@  static void smc_llc_process_cli_add_link(struct smc_link_group *lgr)
 
 	qentry = smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl);
 
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	if (smc_llc_is_local_add_link(&qentry->msg))
 		smc_llc_cli_add_link_invite(qentry->link, qentry);
 	else
 		smc_llc_cli_add_link(qentry->link, qentry);
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 }
 
 static int smc_llc_active_link_count(struct smc_link_group *lgr)
@@ -1545,13 +1545,13 @@  static void smc_llc_process_srv_add_link(struct smc_link_group *lgr)
 
 	qentry = smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl);
 
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	rc = smc_llc_srv_add_link(link, qentry);
 	if (!rc && lgr->type == SMC_LGR_SYMMETRIC) {
 		/* delete any asymmetric link */
 		smc_llc_delete_asym_link(lgr);
 	}
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 	kfree(qentry);
 }
 
@@ -1618,7 +1618,7 @@  static void smc_llc_process_cli_delete_link(struct smc_link_group *lgr)
 		smc_lgr_terminate_sched(lgr);
 		goto out;
 	}
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	/* delete single link */
 	for (lnk_idx = 0; lnk_idx < SMC_LINKS_PER_LGR_MAX; lnk_idx++) {
 		if (lgr->lnk[lnk_idx].link_id != del_llc->link_num)
@@ -1652,7 +1652,7 @@  static void smc_llc_process_cli_delete_link(struct smc_link_group *lgr)
 		smc_lgr_terminate_sched(lgr);
 	}
 out_unlock:
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 out:
 	kfree(qentry);
 }
@@ -1688,7 +1688,7 @@  static void smc_llc_process_srv_delete_link(struct smc_link_group *lgr)
 	int active_links;
 	int i;
 
-	mutex_lock(&lgr->llc_conf_mutex);
+	down_write(&lgr->llc_conf_mutex);
 	qentry = smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl);
 	lnk = qentry->link;
 	del_llc = &qentry->msg.delete_link;
@@ -1744,7 +1744,7 @@  static void smc_llc_process_srv_delete_link(struct smc_link_group *lgr)
 		smc_llc_add_link_local(lnk);
 	}
 out:
-	mutex_unlock(&lgr->llc_conf_mutex);
+	up_write(&lgr->llc_conf_mutex);
 	kfree(qentry);
 }
 
@@ -2158,7 +2158,7 @@  void smc_llc_lgr_init(struct smc_link_group *lgr, struct smc_sock *smc)
 	spin_lock_init(&lgr->llc_flow_lock);
 	init_waitqueue_head(&lgr->llc_flow_waiter);
 	init_waitqueue_head(&lgr->llc_msg_waiter);
-	mutex_init(&lgr->llc_conf_mutex);
+	init_rwsem(&lgr->llc_conf_mutex);
 	lgr->llc_testlink_time = READ_ONCE(net->smc.sysctl_smcr_testlink_time);
 }