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authorJörn Engel <joern@logfs.org>2013-05-30 16:36:51 -0400
committerNicholas Bellinger <nab@linux-iscsi.org>2013-06-14 00:55:49 -0700
commit574780fd5e6ec52bd43e0bdb777a19e4c4c6aa9c (patch)
tree35fcb7d07dd7595c56c3cf3fa0d16c02456a599b /drivers/target
parent317ddd256b9c24b0d78fa8018f80f1e495481a10 (diff)
downloadlinux-linaro-stable-574780fd5e6ec52bd43e0bdb777a19e4c4c6aa9c.tar.gz
target/iscsi: don't corrupt bh_count in iscsit_stop_time2retain_timer()
Here is a fun one. Bug seems to have been introduced by commit 140854cb, almost two years ago. I have no idea why we only started seeing it now, but we did. Rough callgraph: core_tpg_set_initiator_node_queue_depth() `-> spin_lock_irqsave(&tpg->session_lock, flags); `-> lio_tpg_shutdown_session() `-> iscsit_stop_time2retain_timer() `-> spin_unlock_bh(&se_tpg->session_lock); `-> spin_lock_bh(&se_tpg->session_lock); `-> spin_unlock_irqrestore(&tpg->session_lock, flags); core_tpg_set_initiator_node_queue_depth() used to call spin_lock_bh(), but 140854cb changed that to spin_lock_irqsave(). However, lio_tpg_shutdown_session() still claims to be called with spin_lock_bh() held, as does iscsit_stop_time2retain_timer(): * Called with spin_lock_bh(&struct se_portal_group->session_lock) held Stale documentation is mostly annoying, but in this case the dropping the lock with the _bh variant is plain wrong. It is also wrong to drop locks two functions below the lock-holder, but I will ignore that bit for now. After some more locking and unlocking we eventually hit this backtrace: ------------[ cut here ]------------ WARNING: at kernel/softirq.c:159 local_bh_enable_ip+0xe8/0x100() Pid: 24645, comm: lio_helper.py Tainted: G O 3.6.11+ Call Trace: [<ffffffff8103e5ff>] warn_slowpath_common+0x7f/0xc0 [<ffffffffa040ae37>] ? iscsit_inc_conn_usage_count+0x37/0x50 [iscsi_target_mod] [<ffffffff8103e65a>] warn_slowpath_null+0x1a/0x20 [<ffffffff810472f8>] local_bh_enable_ip+0xe8/0x100 [<ffffffff815b8365>] _raw_spin_unlock_bh+0x15/0x20 [<ffffffffa040ae37>] iscsit_inc_conn_usage_count+0x37/0x50 [iscsi_target_mod] [<ffffffffa041149a>] iscsit_stop_session+0xfa/0x1c0 [iscsi_target_mod] [<ffffffffa0417fab>] lio_tpg_shutdown_session+0x7b/0x90 [iscsi_target_mod] [<ffffffffa033ede4>] core_tpg_set_initiator_node_queue_depth+0xe4/0x290 [target_core_mod] [<ffffffffa0409032>] iscsit_tpg_set_initiator_node_queue_depth+0x12/0x20 [iscsi_target_mod] [<ffffffffa0415c29>] lio_target_nacl_store_cmdsn_depth+0xa9/0x180 [iscsi_target_mod] [<ffffffffa0331b49>] target_fabric_nacl_base_attr_store+0x39/0x40 [target_core_mod] [<ffffffff811b857d>] configfs_write_file+0xbd/0x120 [<ffffffff81148f36>] vfs_write+0xc6/0x180 [<ffffffff81149251>] sys_write+0x51/0x90 [<ffffffff815c0969>] system_call_fastpath+0x16/0x1b ---[ end trace 3747632b9b164652 ]--- As a pure band-aid, this patch drops the _bh. Signed-off-by: Joern Engel <joern@logfs.org> Cc: stable <stable@vger.kernel.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target')
-rw-r--r--drivers/target/iscsi/iscsi_target_erl0.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/target/iscsi/iscsi_target_erl0.c b/drivers/target/iscsi/iscsi_target_erl0.c
index 8e6298cc8839..dcb199da06b9 100644
--- a/drivers/target/iscsi/iscsi_target_erl0.c
+++ b/drivers/target/iscsi/iscsi_target_erl0.c
@@ -842,11 +842,11 @@ int iscsit_stop_time2retain_timer(struct iscsi_session *sess)
return 0;
sess->time2retain_timer_flags |= ISCSI_TF_STOP;
- spin_unlock_bh(&se_tpg->session_lock);
+ spin_unlock(&se_tpg->session_lock);
del_timer_sync(&sess->time2retain_timer);
- spin_lock_bh(&se_tpg->session_lock);
+ spin_lock(&se_tpg->session_lock);
sess->time2retain_timer_flags &= ~ISCSI_TF_RUNNING;
pr_debug("Stopped Time2Retain Timer for SID: %u\n",
sess->sid);