Hi,
When I use fio test kernel in the following steps:
1.The sas controller mixes SAS/SATA disks
2.Use fio test all disks
3.Simultaneous enable/disable/link_reset/hard_reset PHY
it will hung in ata_port_wait_eh
Call trace:
__switch_to+0xb4/0x1b8
__schedule+0x1e8/0x718
schedule+0x38/0x90
ata_port_wait_eh+0x70/0xf8
sas_ata_wait_eh+0x24/0x30 [libsas]
transport_sas_phy_reset.isra.3+0x128/0x160 [libsas]
phy_reset_work+0x20/0x30 [libsas]
process_one_work+0x1e4/0x460
worker_thread+0x40/0x450
kthread+0x12c/0x130
ret_from_fork+0x10/0x18
I think the reason is as follows(neither function wakes up the SCSI error
handler):
A thread：
scsi_schedule_eh
spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
shost->host_eh_scheduled++;
scsi_eh_wakeup(shost); --->visit host_busy && host_failed
}
spin_unlock_irqrestore(shost->host_lock, flags);
B thread：
scsi_dec_host_busy
rcu_read_lock();
atomic_dec(&shost->host_busy); --->host_busy and shost_state not in
spinlock, maybe we need to put these in spinlock?
if (unlikely(scsi_host_in_recovery(shost))) {
spin_lock_irqsave(shost->host_lock, flags);
if (shost->host_failed || shost->host_eh_scheduled)
scsi_eh_wakeup(shost);
spin_unlock_irqrestore(shost->host_lock, flags);
}
rcu_read_unlock();
PS: commit 3bd6f43f5(use rcu_read_lock) fix the hung issue if
scsi_eh_scmd_add() is called concurrently with
scsi_host_queue_ready() while shost->host_blocked > 0
Thanks,
zhengbin
