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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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
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In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.