From 3627668c2e2c9459cff874ad34b82d251038da48 Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Thu, 26 Nov 2020 14:29:45 +0100 Subject: 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 Cc: Manish Rangankar Cc: Reviewed-by: Daniel Wagner Signed-off-by: Ahmed S. Darwish Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Martin K. Petersen --- drivers/scsi/qla4xxx/ql4_nx.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) (limited to 'drivers/scsi/qla4xxx/ql4_nx.c') diff --git a/drivers/scsi/qla4xxx/ql4_nx.c b/drivers/scsi/qla4xxx/ql4_nx.c index da903a545b2c..4362d0ebe0e1 100644 --- a/drivers/scsi/qla4xxx/ql4_nx.c +++ b/drivers/scsi/qla4xxx/ql4_nx.c @@ -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; } -- cgit v1.2.3