[PATCH 08/14] scsi: qla4xxx: qla4_82xx_rom_lock(): Remove in_interrupt().

Sebastian Andrzej Siewior
2020-11-26T13:30:38Z

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

qla4_82xx_rom_lock() spins on a certain hardware state until it is
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: qla4_82xx_rom_lock() is always called
from process context. Below is an analysis of its callers:

- ql4_nx.c: qla4_82xx_rom_fast_read(), all process context callers:
=> ql4_nx.c: qla4_82xx_pinit_from_rom(), GFP_KERNEL allocation
=> ql4_nx.c: qla4_82xx_load_from_flash(), msleep() in a loop

- ql4_nx.c: qla4_82xx_pinit_from_rom(), earlier discussed

- ql4_nx.c: qla4_82xx_rom_lock_recovery(), bound to "isp_operations"
->rom_lock_recovery() hook, which has one process context caller,
qla4_8xxx_device_bootstrap(), with callers:
=> ql4_83xx.c: qla4_83xx_need_reset_handler(), process, msleep()
=> ql4_nx.c: qla4_8xxx_device_state_handler(), multiple msleep()s

- ql4_nx.c: qla4_82xx_read_flash_data(), has cond_resched()

Remove the in_interrupt() check. Mark, qla4_82xx_rom_lock(), and the
->rom_lock_recovery() hook, with "Context: task, can sleep".

Change qla4_82xx_rom_lock() implementation to sleep 20ms, instead of a
schedule(), for each spin. This is more deterministic, and it matches
the other implementations bound to ->rom_lock_recovery().

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: Manish Rangankar <mrangankar@marvell.com>
Cc: <GR-QLogic-Storage-Upstream@marvell.com>
---
drivers/scsi/qla4xxx/ql4_def.h | 2 +-
drivers/scsi/qla4xxx/ql4_nx.c | 16 ++++++----------
2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/qla4xxx/ql4_def.h b/drivers/scsi/qla4xxx/ql4_def.h
index 9210547483886..031569c496e57 100644
--- a/drivers/scsi/qla4xxx/ql4_def.h
+++ b/drivers/scsi/qla4xxx/ql4_def.h
@@ -437,7 +437,7 @@ struct isp_operations {
int (*wr_reg_indirect) (struct scsi_qla_host *, uint32_t, uint32_t);
int (*idc_lock) (struct scsi_qla_host *); /* Context: task, can sleep */
void (*idc_unlock) (struct scsi_qla_host *);
- void (*rom_lock_recovery) (struct scsi_qla_host *);
+ void (*rom_lock_recovery) (struct scsi_qla_host *); /* Context: task, can sleep */
void (*queue_mailbox_command) (struct scsi_qla_host *, uint32_t *, int);
void (*process_mailbox_interrupt) (struct scsi_qla_host *, int);
};
diff --git a/drivers/scsi/qla4xxx/ql4_nx.c b/drivers/scsi/qla4xxx/ql4_nx.c
index 4362d0ebe0e15..fd30fbd0d33cb 100644
--- a/drivers/scsi/qla4xxx/ql4_nx.c
+++ b/drivers/scsi/qla4xxx/ql4_nx.c
@@ -871,15 +871,18 @@ qla4_82xx_decode_crb_addr(unsigned long addr)
static long rom_max_timeout = 100;
static long qla4_82xx_rom_lock_timeout = 100;

+/*
+ * Context: task, can_sleep
+ */
static int
qla4_82xx_rom_lock(struct scsi_qla_host *ha)
{
- int i;
int done = 0, timeout = 0;

+ might_sleep();
+
while (!done) {
/* acquire semaphore2 from PCI HW block */
-
done = qla4_82xx_rd_32(ha, QLA82XX_PCIE_REG(PCIE_SEM2_LOCK));
if (done == 1)
break;
@@ -887,14 +890,7 @@ qla4_82xx_rom_lock(struct scsi_qla_host *ha)
return -1;

timeout++;
-
- /* Yield CPU */
- if (!in_interrupt())
- schedule();
- else {
- for (i = 0; i < 20; i++)
- cpu_relax(); /*This a nop instr on i386*/
- }
+ msleep(20);
}
qla4_82xx_wr_32(ha, QLA82XX_ROM_LOCK_ID, ROM_LOCK_DRIVER);
return 0;
--
2.29.2