[PATCH 5.15 675/731] scsi: lpfc: Fix hard lockup when reading the rx_monitor from debugfs

Greg Kroah-Hartman
2022-12-28T15:58:23Z

From: Justin Tee <justin.tee@broadcom.com>

[ Upstream commit c44e50f4a0ec00c2298f31f91bc2c3e9bbd81c7e ]

During I/O and simultaneous cat of /sys/kernel/debug/lpfc/fnX/rx_monitor, a
hard lockup similar to the call trace below may occur.

The spin_lock_bh in lpfc_rx_monitor_report is not protecting from timer
interrupts as expected, so change the strength of the spin lock to _irq.

Kernel panic - not syncing: Hard LOCKUP
CPU: 3 PID: 110402 Comm: cat Kdump: loaded

exception RIP: native_queued_spin_lock_slowpath+91

[IRQ stack]
native_queued_spin_lock_slowpath at ffffffffb814e30b
_raw_spin_lock at ffffffffb89a667a
lpfc_rx_monitor_record at ffffffffc0a73a36 [lpfc]
lpfc_cmf_timer at ffffffffc0abbc67 [lpfc]
__hrtimer_run_queues at ffffffffb8184250
hrtimer_interrupt at ffffffffb8184ab0
smp_apic_timer_interrupt at ffffffffb8a026ba
apic_timer_interrupt at ffffffffb8a01c4f
[End of IRQ stack]

apic_timer_interrupt at ffffffffb8a01c4f
lpfc_rx_monitor_report at ffffffffc0a73c80 [lpfc]
lpfc_rx_monitor_read at ffffffffc0addde1 [lpfc]
full_proxy_read at ffffffffb83e7fc3
vfs_read at ffffffffb833fe71
ksys_read at ffffffffb83402af
do_syscall_64 at ffffffffb800430b
entry_SYSCALL_64_after_hwframe at ffffffffb8a000ad

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20221017164323.14536-2-justintee8345@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/lpfc/lpfc_sli.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index d6e761adf1f1..df3b190fccd1 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -7992,10 +7992,10 @@ u32 lpfc_rx_monitor_report(struct lpfc_hba *phba,
"IO_cnt", "Info", "BWutil(ms)");
}

- /* Needs to be _bh because record is called from timer interrupt
+ /* Needs to be _irq because record is called from timer interrupt
* context
*/
- spin_lock_bh(ring_lock);
+ spin_lock_irq(ring_lock);
while (*head_idx != *tail_idx) {
entry = &ring[*head_idx];

@@ -8039,7 +8039,7 @@ u32 lpfc_rx_monitor_report(struct lpfc_hba *phba,
if (cnt >= max_read_entries)
break;
}
- spin_unlock_bh(ring_lock);
+ spin_unlock_irq(ring_lock);

return cnt;
}
--
2.35.1