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author | Nicholas Bellinger <nab@linux-iscsi.org> | 2017-08-04 23:59:31 -0700 |
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committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2017-08-06 14:41:41 -0700 |
commit | 978d13d60c34818a41fc35962602bdfa5c03f214 (patch) | |
tree | c93d2586f98f345336957007ceda4dcd28605212 /drivers/target/iscsi | |
parent | 6bcbb3174caa5f1ccc894f8ae077631659d5a629 (diff) | |
download | op-kernel-dev-978d13d60c34818a41fc35962602bdfa5c03f214.zip op-kernel-dev-978d13d60c34818a41fc35962602bdfa5c03f214.tar.gz |
iscsi-target: Fix iscsi_np reset hung task during parallel delete
This patch fixes a bug associated with iscsit_reset_np_thread()
that can occur during parallel configfs rmdir of a single iscsi_np
used across multiple iscsi-target instances, that would result in
hung task(s) similar to below where configfs rmdir process context
was blocked indefinately waiting for iscsi_np->np_restart_comp
to finish:
[ 6726.112076] INFO: task dcp_proxy_node_:15550 blocked for more than 120 seconds.
[ 6726.119440] Tainted: G W O 4.1.26-3321 #2
[ 6726.125045] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 6726.132927] dcp_proxy_node_ D ffff8803f202bc88 0 15550 1 0x00000000
[ 6726.140058] ffff8803f202bc88 ffff88085c64d960 ffff88083b3b1ad0 ffff88087fffeb08
[ 6726.147593] ffff8803f202c000 7fffffffffffffff ffff88083f459c28 ffff88083b3b1ad0
[ 6726.155132] ffff88035373c100 ffff8803f202bca8 ffffffff8168ced2 ffff8803f202bcb8
[ 6726.162667] Call Trace:
[ 6726.165150] [<ffffffff8168ced2>] schedule+0x32/0x80
[ 6726.170156] [<ffffffff8168f5b4>] schedule_timeout+0x214/0x290
[ 6726.176030] [<ffffffff810caef2>] ? __send_signal+0x52/0x4a0
[ 6726.181728] [<ffffffff8168d7d6>] wait_for_completion+0x96/0x100
[ 6726.187774] [<ffffffff810e7c80>] ? wake_up_state+0x10/0x10
[ 6726.193395] [<ffffffffa035d6e2>] iscsit_reset_np_thread+0x62/0xe0 [iscsi_target_mod]
[ 6726.201278] [<ffffffffa0355d86>] iscsit_tpg_disable_portal_group+0x96/0x190 [iscsi_target_mod]
[ 6726.210033] [<ffffffffa0363f7f>] lio_target_tpg_store_enable+0x4f/0xc0 [iscsi_target_mod]
[ 6726.218351] [<ffffffff81260c5a>] configfs_write_file+0xaa/0x110
[ 6726.224392] [<ffffffff811ea364>] vfs_write+0xa4/0x1b0
[ 6726.229576] [<ffffffff811eb111>] SyS_write+0x41/0xb0
[ 6726.234659] [<ffffffff8169042e>] system_call_fastpath+0x12/0x71
It would happen because each iscsit_reset_np_thread() sets state
to ISCSI_NP_THREAD_RESET, sends SIGINT, and then blocks waiting
for completion on iscsi_np->np_restart_comp.
However, if iscsi_np was active processing a login request and
more than a single iscsit_reset_np_thread() caller to the same
iscsi_np was blocked on iscsi_np->np_restart_comp, iscsi_np
kthread process context in __iscsi_target_login_thread() would
flush pending signals and only perform a single completion of
np->np_restart_comp before going back to sleep within transport
specific iscsit_transport->iscsi_accept_np code.
To address this bug, add a iscsi_np->np_reset_count and update
__iscsi_target_login_thread() to keep completing np->np_restart_comp
until ->np_reset_count has reached zero.
Reported-by: Gary Guo <ghg@datera.io>
Tested-by: Gary Guo <ghg@datera.io>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target/iscsi')
-rw-r--r-- | drivers/target/iscsi/iscsi_target.c | 1 | ||||
-rw-r--r-- | drivers/target/iscsi/iscsi_target_login.c | 7 |
2 files changed, 6 insertions, 2 deletions
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 12803de..5001261 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -418,6 +418,7 @@ int iscsit_reset_np_thread( return 0; } np->np_thread_state = ISCSI_NP_THREAD_RESET; + atomic_inc(&np->np_reset_count); if (np->np_thread) { spin_unlock_bh(&np->np_thread_lock); diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c index e9bdc8b..dc13afb 100644 --- a/drivers/target/iscsi/iscsi_target_login.c +++ b/drivers/target/iscsi/iscsi_target_login.c @@ -1243,9 +1243,11 @@ static int __iscsi_target_login_thread(struct iscsi_np *np) flush_signals(current); spin_lock_bh(&np->np_thread_lock); - if (np->np_thread_state == ISCSI_NP_THREAD_RESET) { + if (atomic_dec_if_positive(&np->np_reset_count) >= 0) { np->np_thread_state = ISCSI_NP_THREAD_ACTIVE; + spin_unlock_bh(&np->np_thread_lock); complete(&np->np_restart_comp); + return 1; } else if (np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN) { spin_unlock_bh(&np->np_thread_lock); goto exit; @@ -1278,7 +1280,8 @@ static int __iscsi_target_login_thread(struct iscsi_np *np) goto exit; } else if (rc < 0) { spin_lock_bh(&np->np_thread_lock); - if (np->np_thread_state == ISCSI_NP_THREAD_RESET) { + if (atomic_dec_if_positive(&np->np_reset_count) >= 0) { + np->np_thread_state = ISCSI_NP_THREAD_ACTIVE; spin_unlock_bh(&np->np_thread_lock); complete(&np->np_restart_comp); iscsit_put_transport(conn->conn_transport); |