scsi: qla2xxx: Remove in_interrupt() from qla82xx-specific code

scsi: qla2xxx: Remove in_interrupt() from qla82xx-specific code

qla82xx_idc_lock() spins on a certain hardware state until it's updated. At
the end of each spin, if in_interrupt() is true, it does 20 loops of
cpu_relax(). Otherwise, it yields the CPU.

While in_interrupt() is ill-defined and does not provide what the name
suggests, it is not needed here: qla82xx_idc_lock() is always called from
process context. Below is an analysis of its callers, in order of
appearance:

  - qla_nx.c: qla82xx_device_bootstrap(), only called by
    qla82xx_device_state_handler(), has multiple msleep()s.

  - qla_nx.c: qla82xx_need_qsnt_handler(), has one second msleep()

  - qla_nx.c: qla82xx_wait_for_state_change(), one second msleep()

  - qla_nx.c: qla82xx_need_reset_handler(), can sleep up to 10 seconds

  - qla_nx.c: qla82xx_device_state_handler(), has multiple msleep()s

  - qla_nx.c: qla82xx_abort_isp(), if it's a qla82xx controller, calls
    qla82xx_device_state_handler(), which sleeps. It's also bound to
    isp_operations ->abort_isp() hook, where all the callers are in process
    context.

  - qla_nx.c: qla82xx_beacon_on(), bound to isp_operations ->beacon_on()
    hook.  That hook is only called once, in a mutex locked context, from
    qla2x00_beacon_store().

  - qla_nx.c: qla82xx_beacon_off(), bound to isp_operations ->beacon_off()
    hook.  Like ->beacon_on(), it's only called once, in a mutex locked
    context, from qla2x00_beacon_store().

  - qla_nx.c: qla82xx_fw_dump(), calls qla2x00_wait_for_chip_reset(), which
    has msleep() in a loop. It is bound to isp_operations ->fw_dump()
    hook. That hook *is* called from atomic context at qla_isr.c by
    multiple interrupt handlers. Nonetheless, it's other controllers
    interrupt handlers, and not the qla82xx.

  - qla82xx_msix_default() and qla82xx_msix_rsp_q() call
    qla24xx_process_response_queue() which doesn't implement the firmware
    dumping.

  - qla_attr.c: qla2x00_sysfs_write_fw_dump(), and
    qla2x00_sysfs_write_reset(), process-context sysfs ->write() hooks.

  - qla_os.c: qla2x00_probe_one(). PCI ->probe(), process context.

  - qla_os.c: qla2x00_clear_drv_active(), called solely from
    qla2x00_remove_one(), which is PCI ->remove() hook, process context.

  - qla_os.c: qla2x00_do_dpc(), kthread function, process context.

Remove the in_interrupt() check. Change qla82xx_idc_lock() specification to
a purely process-context function. Mark it with "Context: task, might
sleep".

Change qla82xx_idc_lock() implementation to sleep 100ms, instead of a
schedule(), for each spin. This is more deterministic, and it matches the
other qla models idc_lock() functions.

Link: https://lore.kernel.org/r/20201126132952.2287996-5-bigeasy@linutronix.de
Cc: Nilesh Javali <njavali@marvell.com>
Cc: <GR-QLogic-Storage-Upstream@marvell.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>