300ec7415c
Since fc_remote_port_delete() must be called with interrupts enabled, do
not disable interrupts when calling that function. Remove the lockin calls
from around the put_sess() call. This is safe because the function that is
called when the final reference is dropped, qlt_unreg_sess(), grabs the
proper locks. This patch avoids that lockdep reports the following:
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
kworker/2:1/62 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
0000000009e679b3 (&(&k->k_lock)->rlock){+.+.}, at: klist_next+0x43/0x1d0
and this task is already holding:
00000000a033b71c (&(&ha->tgt.sess_lock)->rlock){-...}, at: qla24xx_delete_sess_fn+0x55/0xf0 [qla2xxx_scst]
which would create a new lock dependency:
(&(&ha->tgt.sess_lock)->rlock){-...} -> (&(&k->k_lock)->rlock){+.+.}
but this new dependency connects a HARDIRQ-irq-safe lock:
(&(&ha->tgt.sess_lock)->rlock){-...}
... which became HARDIRQ-irq-safe at:
lock_acquire+0xe3/0x200
_raw_spin_lock_irqsave+0x3d/0x60
qla24xx_report_id_acquisition+0xa69/0xe30 [qla2xxx_scst]
qla24xx_process_response_queue+0x69e/0x1270 [qla2xxx_scst]
qla24xx_msix_rsp_q+0x79/0xf0 [qla2xxx_scst]
__handle_irq_event_percpu+0x79/0x3c0
handle_irq_event_percpu+0x70/0xf0
handle_irq_event+0x5a/0x8b
handle_edge_irq+0x12c/0x310
handle_irq+0x192/0x20a
do_IRQ+0x73/0x160
ret_from_intr+0x0/0x1d
default_idle+0x23/0x1f0
arch_cpu_idle+0x15/0x20
default_idle_call+0x35/0x40
do_idle+0x2bb/0x2e0
cpu_startup_entry+0x1d/0x20
start_secondary+0x2a8/0x320
secondary_startup_64+0xa4/0xb0
to a HARDIRQ-irq-unsafe lock:
(&(&k->k_lock)->rlock){+.+.}
... which became HARDIRQ-irq-unsafe at:
...
lock_acquire+0xe3/0x200
_raw_spin_lock+0x32/0x50
klist_add_tail+0x33/0xb0
device_add+0x7e1/0xb50
device_create_groups_vargs+0x11c/0x150
device_create_with_groups+0x89/0xb0
vtconsole_class_init+0xb2/0x124
do_one_initcall+0xc5/0x3ce
kernel_init_freeable+0x295/0x32e
kernel_init+0x11/0x11b
ret_from_fork+0x3a/0x50
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&(&k->k_lock)->rlock);
local_irq_disable();
lock(&(&ha->tgt.sess_lock)->rlock);
lock(&(&k->k_lock)->rlock);
<Interrupt>
lock(&(&ha->tgt.sess_lock)->rlock);
*** DEADLOCK ***
3 locks held by kworker/2:1/62:
#0: 00000000a4319c16 ((wq_completion)"qla2xxx_wq"){+.+.}, at: process_one_work+0x437/0xa80
#1: 00000000ffa34c42 ((work_completion)(&sess->del_work)){+.+.}, at: process_one_work+0x437/0xa80
#2: 00000000a033b71c (&(&ha->tgt.sess_lock)->rlock){-...}, at: qla24xx_delete_sess_fn+0x55/0xf0 [qla2xxx_scst]
the dependencies between HARDIRQ-irq-safe lock and the holding lock:
-> (&(&ha->tgt.sess_lock)->rlock){-...} ops: 8 {
IN-HARDIRQ-W at:
lock_acquire+0xe3/0x200
_raw_spin_lock_irqsave+0x3d/0x60
qla24xx_report_id_acquisition+0xa69/0xe30 [qla2xxx_scst]
qla24xx_process_response_queue+0x69e/0x1270 [qla2xxx_scst]
qla24xx_msix_rsp_q+0x79/0xf0 [qla2xxx_scst]
__handle_irq_event_percpu+0x79/0x3c0
handle_irq_event_percpu+0x70/0xf0
handle_irq_event+0x5a/0x8b
handle_edge_irq+0x12c/0x310
handle_irq+0x192/0x20a
do_IRQ+0x73/0x160
ret_from_intr+0x0/0x1d
default_idle+0x23/0x1f0
arch_cpu_idle+0x15/0x20
default_idle_call+0x35/0x40
do_idle+0x2bb/0x2e0
cpu_startup_entry+0x1d/0x20
start_secondary+0x2a8/0x320
secondary_startup_64+0xa4/0xb0
INITIAL USE at:
lock_acquire+0xe3/0x200
_raw_spin_lock_irqsave+0x3d/0x60
qla24xx_report_id_acquisition+0xa69/0xe30 [qla2xxx_scst]
qla24xx_process_response_queue+0x69e/0x1270 [qla2xxx_scst]
qla24xx_msix_rsp_q+0x79/0xf0 [qla2xxx_scst]
__handle_irq_event_percpu+0x79/0x3c0
handle_irq_event_percpu+0x70/0xf0
handle_irq_event+0x5a/0x8b
handle_edge_irq+0x12c/0x310
handle_irq+0x192/0x20a
do_IRQ+0x73/0x160
ret_from_intr+0x0/0x1d
default_idle+0x23/0x1f0
arch_cpu_idle+0x15/0x20
default_idle_call+0x35/0x40
do_idle+0x2bb/0x2e0
cpu_startup_entry+0x1d/0x20
start_secondary+0x2a8/0x320
secondary_startup_64+0xa4/0xb0
}
... key at: [<ffffffffa0c0d080>] __key.85462+0x0/0xfffffffffff7df80 [qla2xxx_scst]
... acquired at:
lock_acquire+0xe3/0x200
_raw_spin_lock_irqsave+0x3d/0x60
klist_next+0x43/0x1d0
device_for_each_child+0x96/0x110
scsi_target_block+0x3c/0x40 [scsi_mod]
fc_remote_port_delete+0xe7/0x1c0 [scsi_transport_fc]
qla2x00_mark_device_lost+0xa0b/0xa30 [qla2xxx_scst]
qlt_unreg_sess+0x1c6/0x380 [qla2xxx_scst]
qla24xx_delete_sess_fn+0xe6/0xf0 [qla2xxx_scst]
process_one_work+0x511/0xa80
worker_thread+0x67/0x5b0
kthread+0x1d2/0x1f0
ret_from_fork+0x3a/0x50
the dependencies between the lock to be acquired
and HARDIRQ-irq-unsafe lock:
-> (&(&k->k_lock)->rlock){+.+.} ops: 13831 {
HARDIRQ-ON-W at:
lock_acquire+0xe3/0x200
_raw_spin_lock+0x32/0x50
klist_add_tail+0x33/0xb0
device_add+0x7e1/0xb50
device_create_groups_vargs+0x11c/0x150
device_create_with_groups+0x89/0xb0
vtconsole_class_init+0xb2/0x124
do_one_initcall+0xc5/0x3ce
kernel_init_freeable+0x295/0x32e
kernel_init+0x11/0x11b
ret_from_fork+0x3a/0x50
SOFTIRQ-ON-W at:
lock_acquire+0xe3/0x200
_raw_spin_lock+0x32/0x50
klist_add_tail+0x33/0xb0
device_add+0x7e1/0xb50
device_create_groups_vargs+0x11c/0x150
device_create_with_groups+0x89/0xb0
vtconsole_class_init+0xb2/0x124
do_one_initcall+0xc5/0x3ce
kernel_init_freeable+0x295/0x32e
kernel_init+0x11/0x11b
ret_from_fork+0x3a/0x50
INITIAL USE at:
lock_acquire+0xe3/0x200
_raw_spin_lock+0x32/0x50
klist_add_tail+0x33/0xb0
device_add+0x7e1/0xb50
device_create_groups_vargs+0x11c/0x150
device_create_with_groups+0x89/0xb0
vtconsole_class_init+0xb2/0x124
do_one_initcall+0xc5/0x3ce
kernel_init_freeable+0x295/0x32e
kernel_init+0x11/0x11b
ret_from_fork+0x3a/0x50
}
... key at: [<ffffffff83ed8780>] __key.15491+0x0/0x40
... acquired at:
lock_acquire+0xe3/0x200
_raw_spin_lock_irqsave+0x3d/0x60
klist_next+0x43/0x1d0
device_for_each_child+0x96/0x110
scsi_target_block+0x3c/0x40 [scsi_mod]
fc_remote_port_delete+0xe7/0x1c0 [scsi_transport_fc]
qla2x00_mark_device_lost+0xa0b/0xa30 [qla2xxx_scst]
qlt_unreg_sess+0x1c6/0x380 [qla2xxx_scst]
qla24xx_delete_sess_fn+0xe6/0xf0 [qla2xxx_scst]
process_one_work+0x511/0xa80
worker_thread+0x67/0x5b0
kthread+0x1d2/0x1f0
ret_from_fork+0x3a/0x50
stack backtrace:
CPU: 2 PID: 62 Comm: kworker/2:1 Tainted: G O 5.0.7-dbg+ #8
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
Workqueue: qla2xxx_wq qla24xx_delete_sess_fn [qla2xxx_scst]
Call Trace:
dump_stack+0x86/0xca
check_usage.cold.52+0x473/0x563
__lock_acquire+0x11c0/0x23e0
lock_acquire+0xe3/0x200
_raw_spin_lock_irqsave+0x3d/0x60
klist_next+0x43/0x1d0
device_for_each_child+0x96/0x110
scsi_target_block+0x3c/0x40 [scsi_mod]
fc_remote_port_delete+0xe7/0x1c0 [scsi_transport_fc]
qla2x00_mark_device_lost+0xa0b/0xa30 [qla2xxx_scst]
qlt_unreg_sess+0x1c6/0x380 [qla2xxx_scst]
qla24xx_delete_sess_fn+0xe6/0xf0 [qla2xxx_scst]
process_one_work+0x511/0xa80
worker_thread+0x67/0x5b0
kthread+0x1d2/0x1f0
ret_from_fork+0x3a/0x50
Cc: Himanshu Madhani <hmadhani@marvell.com>
Cc: Giridhar Malavali <gmalavali@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.