There is a long call chain that &fip->ctlr_lock is acquired by isr
fnic_isr_msix_wq_copy() under hard IRQ context. Thus other process context
code acquiring the lock should disable IRQ, otherwise deadlock could happen
if the IRQ preempts the execution while the lock is held in process context
on the same CPU.

[ISR]
fnic_isr_msix_wq_copy()
 -> fnic_wq_copy_cmpl_handler()
 -> fnic_fcpio_cmpl_handler()
 -> fnic_fcpio_flogi_reg_cmpl_handler()
 -> fnic_flush_tx()
 -> fnic_send_frame()
 -> fcoe_ctlr_els_send()
 -> spin_lock_bh(&fip->ctlr_lock)

[Process Context]
1. fcoe_ctlr_timer_work()
 -> fcoe_ctlr_flogi_send()
 -> spin_lock_bh(&fip->ctlr_lock)

2. fcoe_ctlr_recv_work()
 -> fcoe_ctlr_recv_handler()
 -> fcoe_ctlr_recv_els()
 -> fcoe_ctlr_announce()
 -> spin_lock_bh(&fip->ctlr_lock)

3. fcoe_ctlr_recv_work()
 -> fcoe_ctlr_recv_handler()
 -> fcoe_ctlr_recv_els()
 -> fcoe_ctlr_flogi_retry()
 -> spin_lock_bh(&fip->ctlr_lock)

4. -> fcoe_xmit()
 -> fcoe_ctlr_els_send()
 -> spin_lock_bh(&fip->ctlr_lock)

spin_lock_bh() is not enough since fnic_isr_msix_wq_copy() is a
hardirq.

These flaws were found by an experimental static analysis tool I am
developing for irq-related deadlock.

The patch fix the potential deadlocks by spin_lock_irqsave() to disable
hard irq.

Fixes: 794d98e7 ("[SCSI] libfcoe: retry rejected FLOGI to another FCF if possible")
Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
Link: https://lore.kernel.org/r/20230817074708.7509-1-dg573847474@gmail.comReviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>