From: Junxiao Bi <junxiao.bi@oracle.com>
To: linux-scsi@vger.kernel.org, target-devel@vger.kernel.org
Cc: martin.petersen@oracle.com, mchristi@redhat.com,
bvanassche@acm.org, junxiao.bi@oracle.com
Subject: [PATCH] scsi: target: fix deadlock by recursive locking
Date: Mon, 18 Sep 2023 15:58:48 -0700 [thread overview]
Message-ID: <20230918225848.66463-1-junxiao.bi@oracle.com> (raw)
The following call trace shown a deadlock issue due to recursive locking
of mutex "device_mutex" , first lock acquire in target_for_each_device()
and second in target_free_device().
PID: 148266 TASK: ffff8be21ffb5d00 CPU: 10 COMMAND: "iscsi_ttx"
#0 [ffffa2bfc9ec3b18] __schedule at ffffffffa8060e7f
#1 [ffffa2bfc9ec3ba0] schedule at ffffffffa8061224
#2 [ffffa2bfc9ec3bb8] schedule_preempt_disabled at ffffffffa80615ee
#3 [ffffa2bfc9ec3bc8] __mutex_lock at ffffffffa8062fd7
#4 [ffffa2bfc9ec3c40] __mutex_lock_slowpath at ffffffffa80631d3
#5 [ffffa2bfc9ec3c50] mutex_lock at ffffffffa806320c
#6 [ffffa2bfc9ec3c68] target_free_device at ffffffffc0935998 [target_core_mod]
#7 [ffffa2bfc9ec3c90] target_core_dev_release at ffffffffc092f975 [target_core_mod]
#8 [ffffa2bfc9ec3ca0] config_item_put at ffffffffa79d250f
#9 [ffffa2bfc9ec3cd0] config_item_put at ffffffffa79d2583
#10 [ffffa2bfc9ec3ce0] target_devices_idr_iter at ffffffffc0933f3a [target_core_mod]
#11 [ffffa2bfc9ec3d00] idr_for_each at ffffffffa803f6fc
#12 [ffffa2bfc9ec3d60] target_for_each_device at ffffffffc0935670 [target_core_mod]
#13 [ffffa2bfc9ec3d98] transport_deregister_session at ffffffffc0946408 [target_core_mod]
#14 [ffffa2bfc9ec3dc8] iscsit_close_session at ffffffffc09a44a6 [iscsi_target_mod]
#15 [ffffa2bfc9ec3df0] iscsit_close_connection at ffffffffc09a4a88 [iscsi_target_mod]
#16 [ffffa2bfc9ec3df8] finish_task_switch at ffffffffa76e5d07
#17 [ffffa2bfc9ec3e78] iscsit_take_action_for_connection_exit at ffffffffc0991c23 [iscsi_target_mod]
#18 [ffffa2bfc9ec3ea0] iscsi_target_tx_thread at ffffffffc09a403b [iscsi_target_mod]
#19 [ffffa2bfc9ec3f08] kthread at ffffffffa76d8080
#20 [ffffa2bfc9ec3f50] ret_from_fork at ffffffffa8200364
Fixes: 36d4cb460bcb ("scsi: target: Avoid that EXTENDED COPY commands trigger lock inversion")
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
---
drivers/target/target_core_device.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index b7ac60f4a219..b6523d4b9259 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -843,7 +843,6 @@ sector_t target_to_linux_sector(struct se_device *dev, sector_t lb)
EXPORT_SYMBOL(target_to_linux_sector);
struct devices_idr_iter {
- struct config_item *prev_item;
int (*fn)(struct se_device *dev, void *data);
void *data;
};
@@ -853,11 +852,9 @@ static int target_devices_idr_iter(int id, void *p, void *data)
{
struct devices_idr_iter *iter = data;
struct se_device *dev = p;
+ struct config_item *item;
int ret;
- config_item_put(iter->prev_item);
- iter->prev_item = NULL;
-
/*
* We add the device early to the idr, so it can be used
* by backend modules during configuration. We do not want
@@ -867,12 +864,13 @@ static int target_devices_idr_iter(int id, void *p, void *data)
if (!target_dev_configured(dev))
return 0;
- iter->prev_item = config_item_get_unless_zero(&dev->dev_group.cg_item);
- if (!iter->prev_item)
+ item = config_item_get_unless_zero(&dev->dev_group.cg_item);
+ if (!item)
return 0;
mutex_unlock(&device_mutex);
ret = iter->fn(dev, iter->data);
+ config_item_put(item);
mutex_lock(&device_mutex);
return ret;
@@ -895,7 +893,6 @@ int target_for_each_device(int (*fn)(struct se_device *dev, void *data),
mutex_lock(&device_mutex);
ret = idr_for_each(&devices_idr, target_devices_idr_iter, &iter);
mutex_unlock(&device_mutex);
- config_item_put(iter.prev_item);
return ret;
}
--
2.39.2 (Apple Git-143)
next reply other threads:[~2023-09-18 22:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-18 22:58 Junxiao Bi [this message]
2023-09-23 20:49 ` [PATCH] scsi: target: fix deadlock by recursive locking michael.christie
2023-09-27 19:34 ` Martin K. Petersen
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