[PATCH 04/14] scsi: qla2xxx: qla82xx: Remove in_interrupt().

Sebastian Andrzej Siewior
2020-11-26T13:30:36Z

From: "Ahmed S. Darwish" <a.darwish@linutronix.de>

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.

- 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.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Nilesh Javali <njavali@marvell.com>
Cc: <GR-QLogic-Storage-Upstream@marvell.com>
---
drivers/scsi/qla2xxx/qla_def.h | 5 +++++
drivers/scsi/qla2xxx/qla_nx.c | 25 +++++++++++--------------
2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
index ed9b10f8537d6..fe3c0e2f1ce88 100644
--- a/drivers/scsi/qla2xxx/qla_def.h
+++ b/drivers/scsi/qla2xxx/qla_def.h
@@ -3296,8 +3296,10 @@ struct isp_operations {
void (*fw_dump)(struct scsi_qla_host *vha);
void (*mpi_fw_dump)(struct scsi_qla_host *, int);

+ /* Context: task, might sleep */
int (*beacon_on) (struct scsi_qla_host *);
int (*beacon_off) (struct scsi_qla_host *);
+
void (*beacon_blink) (struct scsi_qla_host *);

void *(*read_optrom)(struct scsi_qla_host *, void *,
@@ -3308,7 +3310,10 @@ struct isp_operations {
int (*get_flash_version) (struct scsi_qla_host *, void *);
int (*start_scsi) (srb_t *);
int (*start_scsi_mq) (srb_t *);
+
+ /* Context: task, might sleep */
int (*abort_isp) (struct scsi_qla_host *);
+
int (*iospace_config)(struct qla_hw_data *);
int (*initialize_adapter)(struct scsi_qla_host *);
};
diff --git a/drivers/scsi/qla2xxx/qla_nx.c b/drivers/scsi/qla2xxx/qla_nx.c
index b3ba0de5d4fb8..b2017f1c35044 100644
--- a/drivers/scsi/qla2xxx/qla_nx.c
+++ b/drivers/scsi/qla2xxx/qla_nx.c
@@ -489,29 +489,26 @@ qla82xx_rd_32(struct qla_hw_data *ha, ulong off_in)
return data;
}

-#define IDC_LOCK_TIMEOUT 100000000
+/*
+ * Context: task, might sleep
+ */
int qla82xx_idc_lock(struct qla_hw_data *ha)
{
- int i;
- int done = 0, timeout = 0;
+ const int delay_ms = 100, timeout_ms = 2000;
+ int done, total = 0;

- while (!done) {
+ might_sleep();
+
+ while (true) {
/* acquire semaphore5 from PCI HW block */
done = qla82xx_rd_32(ha, QLA82XX_PCIE_REG(PCIE_SEM5_LOCK));
if (done == 1)
break;
- if (timeout >= IDC_LOCK_TIMEOUT)
+ if (WARN_ON_ONCE(total >= timeout_ms))
return -1;

- timeout++;
-
- /* Yield CPU */
- if (!in_interrupt())
- schedule();
- else {
- for (i = 0; i < 20; i++)
- cpu_relax();
- }
+ total += delay_ms;
+ msleep(delay_ms);
}

return 0;
--
2.29.2