[PATCH 03/14] scsi: qla4xxx: qla4_82xx_crb_win_lock(): Remove in_interrupt().

Sebastian Andrzej Siewior
2020-11-26T13:30:34Z

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

qla4_82xx_crb_win_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.

The in_interrupt() macro is ill-defined as it does not provide what the
name suggests, and it does not catch the intended use-case here.

qla4_82xx_crb_win_lock() is always invoked with scsi_qla_host::hw_lock
acquired, with disabled interrupts. If the caller is in process context,
as in qla4_82xx_need_reset_handler(), then in_interrupt() will return
false even though it is not allowed to call schedule().

Remove the in_interrupt() check.

Change qla4_82xx_crb_win_lock() specification to a purely atomic
function. Mark it as static, remove its forward declaration, and move it
above its callers. To avoid hammering the PCI bus while spinning, use a
10 micro-second delay instead of cpu_relax().

Fixes: f4f5df23bf72 ("[SCSI] qla4xxx: Added support for ISP82XX")
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_glbl.h | 1 -
drivers/scsi/qla4xxx/ql4_nx.c | 63 +++++++++++++++------------------
2 files changed, 29 insertions(+), 35 deletions(-)

diff --git a/drivers/scsi/qla4xxx/ql4_glbl.h b/drivers/scsi/qla4xxx/ql4_glbl.h
index b8f02210aeb03..ea60057b2e20a 100644
--- a/drivers/scsi/qla4xxx/ql4_glbl.h
+++ b/drivers/scsi/qla4xxx/ql4_glbl.h
@@ -114,7 +114,6 @@ irqreturn_t qla4_82xx_intr_handler(int irq, void *dev_id);
void qla4_82xx_queue_iocb(struct scsi_qla_host *ha);
void qla4_82xx_complete_iocb(struct scsi_qla_host *ha);

-int qla4_82xx_crb_win_lock(struct scsi_qla_host *);
void qla4_82xx_crb_win_unlock(struct scsi_qla_host *);
int qla4_82xx_pci_get_crb_addr_2M(struct scsi_qla_host *, ulong *);
void qla4_82xx_wr_32(struct scsi_qla_host *, ulong, u32);
diff --git a/drivers/scsi/qla4xxx/ql4_nx.c b/drivers/scsi/qla4xxx/ql4_nx.c
index f1767b21076f7..da903a545b2c0 100644
--- a/drivers/scsi/qla4xxx/ql4_nx.c
+++ b/drivers/scsi/qla4xxx/ql4_nx.c
@@ -375,6 +375,35 @@ qla4_82xx_pci_set_crbwindow_2M(struct scsi_qla_host *ha, ulong *off)
*off = (*off & MASK(16)) + CRB_INDIRECT_2M + ha->nx_pcibase;
}

+#define CRB_WIN_LOCK_TIMEOUT 100000000
+
+/*
+ * Context: atomic
+ */
+static int qla4_82xx_crb_win_lock(struct scsi_qla_host *ha)
+{
+ int done = 0, timeout = 0;
+
+ while (!done) {
+ /* acquire semaphore3 from PCI HW block */
+ done = qla4_82xx_rd_32(ha, QLA82XX_PCIE_REG(PCIE_SEM7_LOCK));
+ if (done == 1)
+ break;
+ if (timeout >= CRB_WIN_LOCK_TIMEOUT)
+ return -1;
+
+ timeout++;
+ udelay(10);
+ }
+ qla4_82xx_wr_32(ha, QLA82XX_CRB_WIN_LOCK_ID, ha->func_num);
+ return 0;
+}
+
+void qla4_82xx_crb_win_unlock(struct scsi_qla_host *ha)
+{
+ qla4_82xx_rd_32(ha, QLA82XX_PCIE_REG(PCIE_SEM7_UNLOCK));
+}
+
void
qla4_82xx_wr_32(struct scsi_qla_host *ha, ulong off, u32 data)
{
@@ -475,40 +504,6 @@ int qla4_82xx_md_wr_32(struct scsi_qla_host *ha, uint32_t off, uint32_t data)
return rval;
}

-#define CRB_WIN_LOCK_TIMEOUT 100000000
-
-int qla4_82xx_crb_win_lock(struct scsi_qla_host *ha)
-{
- int i;
- int done = 0, timeout = 0;
-
- while (!done) {
- /* acquire semaphore3 from PCI HW block */
- done = qla4_82xx_rd_32(ha, QLA82XX_PCIE_REG(PCIE_SEM7_LOCK));
- if (done == 1)
- break;
- if (timeout >= CRB_WIN_LOCK_TIMEOUT)
- return -1;
-
- timeout++;
-
- /* Yield CPU */
- if (!in_interrupt())
- schedule();
- else {
- for (i = 0; i < 20; i++)
- cpu_relax(); /*This a nop instr on i386*/
- }
- }
- qla4_82xx_wr_32(ha, QLA82XX_CRB_WIN_LOCK_ID, ha->func_num);
- return 0;
-}
-
-void qla4_82xx_crb_win_unlock(struct scsi_qla_host *ha)
-{
- qla4_82xx_rd_32(ha, QLA82XX_PCIE_REG(PCIE_SEM7_UNLOCK));
-}
-
#define IDC_LOCK_TIMEOUT 100000000

/**
--
2.29.2