openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

scsi: qla4xxx: Remove in_interrupt() from qla4_82xx_idc_lock() 

qla4_82xx_idc_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_idc_lock() is always called from
process context. Below is an analysis of its callers:

  - ql4_nx.c: qla4_82xx_need_reset_handler(), 1-second msleep() in a
    loop.

  - ql4_nx.c: qla4_82xx_isp_reset(), calls
    qla4_8xxx_device_state_handler(), which has multiple msleep()s.

Beside direct calls, qla4_82xx_idc_lock() is also bound to isp_operations
->idc_lock() hook. Other functions which are bound to the same hook,
e.g. qla4_83xx_drv_lock(), also have an msleep(). For completeness, below
is an analysis of all callers of that hook:

  - ql4_83xx.c: qla4_83xx_need_reset_handler(), has an msleep()

  - ql4_83xx.c: qla4_83xx_isp_reset(), calls
    qla4_8xxx_device_state_handler(), which has multiple msleep()s.

  - ql4_83xx.c: qla4_83xx_disable_pause(), all process context callers:
    => ql4_mbx.c: qla4xxx_mailbox_command(), msleep(), mutex_lock()
    => ql4_os.c: qla4xxx_recover_adapter(), schedule_timeout() in loop
    => ql4_os.c: qla4xxx_do_dpc(), workqueue context

  - ql4_attr.c: qla4_8xxx_sysfs_write_fw_dump(), sysfs bin_attribute
    ->write() hook, process context

  - ql4_mbx.c: qla4xxx_mailbox_command(), earlier discussed

  - ql4_nx.c: qla4_8xxx_device_bootstrap(), callers:
    => ql4_83xx.c: qla4_83xx_need_reset_handler(), process, msleep()
    => ql4_nx.c: qla4_8xxx_device_state_handler(), earlier discussed

  - ql4_nx.c: qla4_8xxx_need_qsnt_handler(), callers:
    => ql4_nx.c: qla4_8xxx_device_state_handler(), multiple msleep()s
    => ql4_os.c: qla4xxx_do_dpc(), workqueue context

  - ql4_nx.c: qla4_8xxx_update_idc_reg(), callers:
    => ql4_nx.c: qla4_8xxx_device_state_handler(), earlier discussed
    => ql4_os.c: qla4_8xxx_error_recovery(), only called by
    qla4xxx_pci_slot_reset(), which is bound to PCI ->slot_reset()
    process-context hook

  - ql4_nx.c: qla4_8xxx_device_state_handler(), earlier discussed

  - ql4_os.c: qla4xxx_recover_adapter(), earlier discussed

  - ql4_os.c: qla4xxx_do_dpc(), earlier discussed

Remove the in_interrupt() check. Mark, qla4_82xx_idc_lock(), and the
->idc_lock() hook itself, with "Context: task, can sleep".

Change qla4_82xx_idc_lock() implementation to sleep 100ms, instead of a
schedule(), for each spin. This is more deterministic, and it matches other
PCI HW locking functions in the driver.

Link: https://lore.kernel.org/r/20201126132952.2287996-8-bigeasy@linutronix.de
Cc: Nilesh Javali <njavali@marvell.com>
Cc: Manish Rangankar <mrangankar@marvell.com>
Cc: <GR-QLogic-Storage-Upstream@marvell.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>
This commit is contained in:
Ahmed S. Darwish 2020-11-26 14:29:45 +01:00 committed by Martin K. Petersen
parent 4f6a57c23b
commit 3627668c2e
2 changed files with 6 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/scsi/qla4xxx/ql4_def.h
View File

@ -435,7 +435,7 @@ struct isp_operations {
void (*wr_reg_direct) (struct scsi_qla_host *, ulong, uint32_t);
int (*rd_reg_indirect) (struct scsi_qla_host *, uint32_t, uint32_t *);
int (*wr_reg_indirect) (struct scsi_qla_host *, uint32_t, uint32_t);
int (*idc_lock) (struct scsi_qla_host *);
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 (*queue_mailbox_command) (struct scsi_qla_host *, uint32_t *, int);

14
drivers/scsi/qla4xxx/ql4_nx.c
View File

@ -512,12 +512,15 @@ int qla4_82xx_md_wr_32(struct scsi_qla_host *ha, uint32_t off, uint32_t data)
*
* General purpose lock used to synchronize access to
* CRB_DEV_STATE, CRB_DEV_REF_COUNT, etc.
*
* Context: task, can sleep
**/
int qla4_82xx_idc_lock(struct scsi_qla_host *ha)
{
int i;
int done = 0, timeout = 0;
might_sleep();
while (!done) {
/* acquire semaphore5 from PCI HW block */
done = qla4_82xx_rd_32(ha, QLA82XX_PCIE_REG(PCIE_SEM5_LOCK));
@ -527,14 +530,7 @@ int qla4_82xx_idc_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(100);
}
return 0;
}