On Thu, Nov 26, 2020 at 02:29:45PM +0100, Sebastian Andrzej Siewior wrote: > From: "Ahmed S. Darwish" <a.darwish@xxxxxxxxxxxxx> > > 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(), multipe 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. > > Signed-off-by: Ahmed S. Darwish <a.darwish@xxxxxxxxxxxxx> > Cc: Nilesh Javali <njavali@xxxxxxxxxxx> > Cc: Manish Rangankar <mrangankar@xxxxxxxxxxx> > Cc: <GR-QLogic-Storage-Upstream@xxxxxxxxxxx> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Reviewed-by: Daniel Wagner <dwagner@xxxxxxx>
