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Fixing race leading to lost external unblock requests

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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@6650 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Vladislav Bolkhovitin
2015-11-10 03:29:11 +00:00
parent 5b92182215
commit 72ca9f8055
4 changed files with 34 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
scst/src/scst_lib.c
View File

@@ -7055,7 +7055,7 @@ void scst_stpg_del_unblock_next(struct scst_cmd *cmd)
EXTRACHECKS_BUG_ON(!cmd->cmd_on_global_stpg_list);
TRACE_DBG("STPG cmd %p: unblocking next", cmd);
TRACE_DBG("STPG cmd %p done: unblocking next", cmd);
list_del(&cmd->global_stpg_list_entry);
cmd->cmd_on_global_stpg_list = 0;
@@ -14171,15 +14171,15 @@ static void scst_sync_ext_blocking_done(struct scst_device *dev,
return;
}
int scst_ext_block_dev(struct scst_device *dev, bool sync,
ext_blocker_done_fn_t done_fn, const uint8_t *priv, int priv_len)
int scst_ext_block_dev(struct scst_device *dev, ext_blocker_done_fn_t done_fn,
const uint8_t *priv, int priv_len, int flags)
{
int res;
struct scst_ext_blocker *b;
TRACE_ENTRY();
if (sync)
if (flags & SCST_EXT_BLOCK_SYNC)
priv_len = sizeof(void *);
b = kzalloc(sizeof(*b) + priv_len, GFP_KERNEL);
@@ -14190,8 +14190,8 @@ int scst_ext_block_dev(struct scst_device *dev, bool sync,
goto out;
}
TRACE_MGMT_DBG("New (%d) %s ext blocker %p for dev %s", dev->ext_blocks_cnt+1,
sync ? "sync" : "async", b, dev->virt_name);
TRACE_MGMT_DBG("New %d ext blocker %p for dev %s (flags %x)",
dev->ext_blocks_cnt+1, b, dev->virt_name, flags);
spin_lock_bh(&dev->dev_lock);
@@ -14207,10 +14207,15 @@ int scst_ext_block_dev(struct scst_device *dev, bool sync,
} else
scst_block_dev(dev);
if (flags & SCST_EXT_BLOCK_STPG) {
WARN_ON(dev->stpg_ext_blocked);
dev->stpg_ext_blocked = 1;
}
dev->ext_blocks_cnt++;
TRACE_DBG("ext_blocks_cnt %d", dev->ext_blocks_cnt);
if (sync && (dev->on_dev_cmd_count == 0)) {
if ((flags & SCST_EXT_BLOCK_SYNC) && (dev->on_dev_cmd_count == 0)) {
TRACE_DBG("No commands to wait for sync blocking (dev %s)",
dev->virt_name);
spin_unlock_bh(&dev->dev_lock);
@@ -14220,7 +14225,7 @@ int scst_ext_block_dev(struct scst_device *dev, bool sync,
list_add_tail(&b->ext_blockers_list_entry, &dev->ext_blockers_list);
dev->ext_blocking_pending = 1;
if (sync) {
if (flags & SCST_EXT_BLOCK_SYNC) {
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(w);
b->ext_blocker_done_fn = scst_sync_ext_blocking_done;
@@ -14254,7 +14259,7 @@ out:
return res;
out_free_success:
sBUG_ON(!sync);
sBUG_ON(!(flags & SCST_EXT_BLOCK_SYNC));
kfree(b);
goto out_success;
}
@@ -14271,8 +14276,14 @@ void scst_ext_unblock_dev(struct scst_device *dev, bool stpg)
}
if ((dev->ext_blocks_cnt == 1) && dev->stpg_ext_blocked && !stpg) {
TRACE_DBG("Can not unblock internal STPG ext block (dev %s)",
dev->virt_name);
/*
* User space is sending too many unblock calls during
* STPG processing
*/
TRACE_MGMT_DBG("Can not unblock internal STPG ext block "
"(dev %s, ext_blocks_cnt %d, stpg_ext_blocked %d, stpg %d)",
dev->virt_name, dev->ext_blocks_cnt,
dev->stpg_ext_blocked, stpg);
goto out_unlock;
}
@@ -14287,7 +14298,7 @@ void scst_ext_unblock_dev(struct scst_device *dev, bool stpg)
spin_unlock_bh(&dev->dev_lock);
TRACE_DBG("Ext unblock (dev %s): still pending...",
dev->virt_name);
rc = scst_ext_block_dev(dev, true, NULL, NULL, 0);
rc = scst_ext_block_dev(dev, NULL, NULL, 0, SCST_EXT_BLOCK_SYNC);
if (rc != 0) {
/* Oops, have to poll */
PRINT_WARNING("scst_ext_block_dev(dev %s) failed, "

6
scst/src/scst_priv.h
View File

@@ -718,8 +718,10 @@ bool __scst_check_blocked_dev(struct scst_cmd *cmd);
void __scst_check_unblock_dev(struct scst_cmd *cmd);
void scst_check_unblock_dev(struct scst_cmd *cmd);
int scst_ext_block_dev(struct scst_device *dev, bool sync,
ext_blocker_done_fn_t done_fn, const uint8_t *priv, int priv_len);
#define SCST_EXT_BLOCK_SYNC 1
#define SCST_EXT_BLOCK_STPG 2
int scst_ext_block_dev(struct scst_device *dev, ext_blocker_done_fn_t done_fn,
const uint8_t *priv, int priv_len, int flags);
void scst_ext_unblock_dev(struct scst_device *dev, bool stpg);
void __scst_ext_blocking_done(struct scst_device *dev);
void scst_ext_blocking_done(struct scst_device *dev);

6
scst/src/scst_sysfs.c
View File

@@ -3560,10 +3560,10 @@ static ssize_t scst_dev_block_store(struct kobject *kobj,
"data_len %d)", dev->virt_name, sync, data_start, data_len);
if (sync)
res = scst_ext_block_dev(dev, true, NULL, NULL, 0);
res = scst_ext_block_dev(dev, NULL, NULL, 0, SCST_EXT_BLOCK_SYNC);
else
res = scst_ext_block_dev(dev, false, scst_sysfs_ext_blocking_done,
data_start, data_len);
res = scst_ext_block_dev(dev, scst_sysfs_ext_blocking_done,
data_start, data_len, 0);
if (res != 0)
goto out;

14
scst/src/scst_tg.c
View File

@@ -1852,17 +1852,11 @@ int scst_tg_set_group_info(struct scst_cmd *cmd)
atomic_inc(&wait->stpg_wait_left);
spin_lock_bh(&dev->dev_lock);
WARN_ON(dgd->dev->stpg_ext_blocked);
dgd->dev->stpg_ext_blocked = 1;
spin_unlock_bh(&dev->dev_lock);
rc = scst_ext_block_dev(dgd->dev, false,
scst_stpg_ext_blocking_done, (uint8_t *)&wait,
sizeof(wait));
rc = scst_ext_block_dev(dgd->dev, scst_stpg_ext_blocking_done,
(uint8_t *)&wait, sizeof(wait), SCST_EXT_BLOCK_STPG);
if (rc != 0) {
TRACE_DBG("scst_ext_block_dev() returned %d, "
"stepping back (cmd %p)", rc, cmd);
TRACE_DBG("scst_ext_block_dev() failed "
"with %d, reverting (cmd %p)", rc, cmd);
wait->status = rc;
wait->dg = dg;
atomic_dec(&wait->stpg_wait_left);