mirrors/scst
1
0
Fork 0
mirror of https://github.com/SCST-project/scst.git synced 2026-05-23 13:41:27 +00:00
Code Issues Packages Projects Releases Wiki Activity

scst_lib: Move synchronize_rcu() calls out of loops to reduce overhead

Browse Source 
This patch refactors the code by accumulating the target devices into a
temporary list and moving the synchronize_rcu() call outside of the
loops. By doing so, we reduce the number of synchronize_rcu() calls to
one, improving the efficiency of the cleanup process.

Fixes: https://github.com/SCST-project/scst/issues/229
This commit is contained in:
Gleb Chesnokov
2024-11-18 18:28:33 +03:00
parent cc713322e7
commit f265dc450f
2 changed files with 56 additions and 47 deletions
Download Patch File Download Diff File Expand all files Collapse all files

102
scst/src/scst_lib.c
View File

@@ -4758,11 +4758,9 @@ int scst_acg_del_lun(struct scst_acg *acg, uint64_t lun,
synchronize_rcu();
mutex_lock(&scst_mutex);
list_for_each_entry_safe(tgt_dev, tt, &tgt_dev_list,
extra_tgt_dev_list_entry) {
list_for_each_entry_safe(tgt_dev, tt, &tgt_dev_list, extra_tgt_dev_list_entry)
scst_free_tgt_dev(tgt_dev);
}
scst_free_acg_dev(acg_dev);
out:
@@ -4808,10 +4806,9 @@ int scst_acg_repl_lun(struct scst_acg *acg, struct kobject *parent,
synchronize_rcu();
mutex_lock(&scst_mutex);
list_for_each_entry_safe(tgt_dev, tt, &tgt_dev_list,
extra_tgt_dev_list_entry) {
list_for_each_entry_safe(tgt_dev, tt, &tgt_dev_list, extra_tgt_dev_list_entry)
scst_free_tgt_dev(tgt_dev);
}
if (acg_dev)
scst_free_acg_dev(acg_dev);
@@ -4931,20 +4928,20 @@ static void scst_del_acg(struct scst_acg *acg)
static void scst_free_acg(struct scst_acg *acg)
{
struct scst_acg_dev *acg_dev, *acg_dev_tmp;
struct scst_acn *acn, *acnt;
struct scst_acn *acn, *acn_tmp;
struct scst_session *sess;
struct scst_tgt *tgt = acg->tgt;
struct scst_tgt_dev *tgt_dev, *tt;
LIST_HEAD(tgt_dev_list);
lockdep_assert_held(&scst_mutex);
/* For procfs acg->tgt could be NULL */
TRACE_DBG("Freeing acg %s/%s", tgt ? tgt->tgt_name : "(tgt=NULL)", acg->acg_name);
list_for_each_entry_safe(acg_dev, acg_dev_tmp, &acg->acg_dev_list,
acg_dev_list_entry) {
struct scst_tgt_dev *tgt_dev, *tt;
list_for_each_entry_safe(tgt_dev, tt,
&acg_dev->dev->dev_tgt_dev_list,
dev_tgt_dev_list_entry) {
list_for_each_entry_safe(acg_dev, acg_dev_tmp, &acg->acg_dev_list, acg_dev_list_entry) {
list_for_each_entry_safe(tgt_dev, tt, &acg_dev->dev->dev_tgt_dev_list,
dev_tgt_dev_list_entry) {
if (tgt_dev->acg_dev == acg_dev) {
sess = tgt_dev->sess;
@@ -4952,17 +4949,19 @@ static void scst_free_acg(struct scst_acg *acg)
scst_del_tgt_dev(tgt_dev);
mutex_unlock(&sess->tgt_dev_list_mutex);
synchronize_rcu();
scst_free_tgt_dev(tgt_dev);
list_add_tail(&tgt_dev->extra_tgt_dev_list_entry, &tgt_dev_list);
}
}
scst_free_acg_dev(acg_dev);
}
list_for_each_entry_safe(acn, acnt, &acg->acn_list, acn_list_entry) {
scst_free_acn(acn,
list_is_last(&acn->acn_list_entry, &acg->acn_list));
}
synchronize_rcu();
list_for_each_entry_safe(tgt_dev, tt, &tgt_dev_list, extra_tgt_dev_list_entry)
scst_free_tgt_dev(tgt_dev);
list_for_each_entry_safe(acn, acn_tmp, &acg->acn_list, acn_list_entry)
scst_free_acn(acn, list_is_last(&acn->acn_list_entry, &acg->acn_list));
kfree(acg->acg_name);
kfree(acg);
@@ -4982,7 +4981,10 @@ static void scst_release_acg_work(struct work_struct *work)
struct scst_acg *acg = release_work->acg;
kfree(release_work);
mutex_lock(&scst_mutex);
scst_free_acg(acg);
mutex_unlock(&scst_mutex);
}
static void scst_release_acg(struct kref *kref)
@@ -5701,6 +5703,37 @@ static void scst_free_tgt_dev(struct scst_tgt_dev *tgt_dev)
return;
}
/* scst_mutex supposed to be held */
static void scst_sess_free_tgt_devs(struct scst_session *sess)
{
int i;
struct scst_tgt_dev *tgt_dev, *tt;
LIST_HEAD(tgt_dev_list);
TRACE_ENTRY();
lockdep_assert_held(&scst_mutex);
mutex_lock(&sess->tgt_dev_list_mutex);
for (i = 0; i < SESS_TGT_DEV_LIST_HASH_SIZE; i++) {
struct list_head *head = &sess->sess_tgt_dev_list[i];
list_for_each_entry_safe(tgt_dev, tt, head, sess_tgt_dev_list_entry) {
scst_del_tgt_dev(tgt_dev);
list_add_tail(&tgt_dev->extra_tgt_dev_list_entry, &tgt_dev_list);
}
INIT_LIST_HEAD(head);
}
mutex_unlock(&sess->tgt_dev_list_mutex);
synchronize_rcu();
list_for_each_entry_safe(tgt_dev, tt, &tgt_dev_list, extra_tgt_dev_list_entry)
scst_free_tgt_dev(tgt_dev);
TRACE_EXIT();
}
/* scst_mutex supposed to be held */
int scst_sess_alloc_tgt_devs(struct scst_session *sess)
{
@@ -5710,6 +5743,8 @@ int scst_sess_alloc_tgt_devs(struct scst_session *sess)
TRACE_ENTRY();
lockdep_assert_held(&scst_mutex);
list_for_each_entry(acg_dev, &sess->acg->acg_dev_list,
acg_dev_list_entry) {
res = scst_alloc_add_tgt_dev(sess, acg_dev, &tgt_dev);
@@ -5728,31 +5763,6 @@ out_free:
goto out;
}
void scst_sess_free_tgt_devs(struct scst_session *sess)
{
int i;
struct scst_tgt_dev *tgt_dev, *t;
TRACE_ENTRY();
mutex_lock(&sess->tgt_dev_list_mutex);
for (i = 0; i < SESS_TGT_DEV_LIST_HASH_SIZE; i++) {
struct list_head *head = &sess->sess_tgt_dev_list[i];
list_for_each_entry_safe(tgt_dev, t, head,
sess_tgt_dev_list_entry) {
scst_del_tgt_dev(tgt_dev);
synchronize_rcu();
scst_free_tgt_dev(tgt_dev);
}
INIT_LIST_HEAD(head);
}
mutex_unlock(&sess->tgt_dev_list_mutex);
TRACE_EXIT();
return;
}
/* The activity supposed to be suspended and scst_mutex held */
int scst_acg_add_acn(struct scst_acg *acg, const char *name)
{

1
scst/src/scst_priv.h
View File

@@ -365,7 +365,6 @@ struct scst_acg *scst_find_acg(const struct scst_session *sess);
void scst_check_reassign_sessions(void);
int scst_sess_alloc_tgt_devs(struct scst_session *sess);
void scst_sess_free_tgt_devs(struct scst_session *sess);
struct scst_tgt_dev *scst_lookup_tgt_dev(struct scst_session *sess, u64 lun);
void scst_nexus_loss(struct scst_tgt_dev *tgt_dev, bool queue_UA);