From 390935acac21f3ea1a130bdca8eb9397cb293643 Mon Sep 17 00:00:00 2001 From: Peter Oberparleiter Date: Mon, 7 Dec 2009 12:51:18 +0100 Subject: [PATCH] [S390] cio: introduce subchannel todos Ensure that current and future users of sch->work do not overwrite each other by introducing a single mechanism for delayed subchannel work. Signed-off-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- drivers/s390/cio/cio.h | 8 ++++++- drivers/s390/cio/css.c | 48 +++++++++++++++++++++++++++++++++++++++ drivers/s390/cio/css.h | 3 +++ drivers/s390/cio/device.c | 23 ++++--------------- 4 files changed, 63 insertions(+), 19 deletions(-) diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h index 2e43558c704b..bf7f80f5a330 100644 --- a/drivers/s390/cio/cio.h +++ b/drivers/s390/cio/cio.h @@ -68,6 +68,11 @@ struct schib { __u8 mda[4]; /* model dependent area */ } __attribute__ ((packed,aligned(4))); +enum sch_todo { + SCH_TODO_NOTHING, + SCH_TODO_UNREG, +}; + /* subchannel data structure used by I/O subroutines */ struct subchannel { struct subchannel_id schid; @@ -95,7 +100,8 @@ struct subchannel { struct device dev; /* entry in device tree */ struct css_driver *driver; void *private; /* private per subchannel type data */ - struct work_struct work; + enum sch_todo todo; + struct work_struct todo_work; struct schib_config config; } __attribute__ ((aligned(8))); diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index b4df5a56cfe2..92ff88ac1107 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -133,6 +133,8 @@ out: return rc; } +static void css_sch_todo(struct work_struct *work); + static struct subchannel * css_alloc_subchannel(struct subchannel_id schid) { @@ -147,6 +149,7 @@ css_alloc_subchannel(struct subchannel_id schid) kfree(sch); return ERR_PTR(ret); } + INIT_WORK(&sch->todo_work, css_sch_todo); return sch; } @@ -190,6 +193,51 @@ void css_sch_device_unregister(struct subchannel *sch) } EXPORT_SYMBOL_GPL(css_sch_device_unregister); +static void css_sch_todo(struct work_struct *work) +{ + struct subchannel *sch; + enum sch_todo todo; + + sch = container_of(work, struct subchannel, todo_work); + /* Find out todo. */ + spin_lock_irq(sch->lock); + todo = sch->todo; + CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid, + sch->schid.sch_no, todo); + sch->todo = SCH_TODO_NOTHING; + spin_unlock_irq(sch->lock); + /* Perform todo. */ + if (todo == SCH_TODO_UNREG) + css_sch_device_unregister(sch); + /* Release workqueue ref. */ + put_device(&sch->dev); +} + +/** + * css_sched_sch_todo - schedule a subchannel operation + * @sch: subchannel + * @todo: todo + * + * Schedule the operation identified by @todo to be performed on the slow path + * workqueue. Do nothing if another operation with higher priority is already + * scheduled. Needs to be called with subchannel lock held. + */ +void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo) +{ + CIO_MSG_EVENT(4, "sch_todo: sched sch=0.%x.%04x todo=%d\n", + sch->schid.ssid, sch->schid.sch_no, todo); + if (sch->todo >= todo) + return; + /* Get workqueue ref. */ + if (!get_device(&sch->dev)) + return; + sch->todo = todo; + if (!queue_work(slow_path_wq, &sch->todo_work)) { + /* Already queued, release workqueue ref. */ + put_device(&sch->dev); + } +} + static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw) { int i; diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h index 68d6b0bf151c..fe84b92cde60 100644 --- a/drivers/s390/cio/css.h +++ b/drivers/s390/cio/css.h @@ -11,6 +11,8 @@ #include #include +#include "cio.h" + /* * path grouping stuff */ @@ -151,4 +153,5 @@ int css_sch_is_valid(struct schib *); extern struct workqueue_struct *slow_path_wq; void css_wait_for_slow_path(void); +void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo); #endif diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c index 6097763f1035..0dcfc0ee3d81 100644 --- a/drivers/s390/cio/device.c +++ b/drivers/s390/cio/device.c @@ -1051,23 +1051,6 @@ static void io_subchannel_init_fields(struct subchannel *sch) io_subchannel_init_config(sch); } -static void io_subchannel_do_unreg(struct work_struct *work) -{ - struct subchannel *sch; - - sch = container_of(work, struct subchannel, work); - css_sch_device_unregister(sch); - put_device(&sch->dev); -} - -/* Schedule unregister if we have no cdev. */ -static void io_subchannel_schedule_removal(struct subchannel *sch) -{ - get_device(&sch->dev); - INIT_WORK(&sch->work, io_subchannel_do_unreg); - queue_work(slow_path_wq, &sch->work); -} - /* * Note: We always return 0 so that we bind to the device even on error. * This is needed so that our remove function is called on unregister. @@ -1124,7 +1107,9 @@ static int io_subchannel_probe(struct subchannel *sch) return 0; out_schedule: - io_subchannel_schedule_removal(sch); + spin_lock_irq(sch->lock); + css_sched_sch_todo(sch, SCH_TODO_UNREG); + spin_unlock_irq(sch->lock); return 0; } @@ -1469,6 +1454,8 @@ static int io_subchannel_sch_event(struct subchannel *sch, int process) spin_lock_irqsave(sch->lock, flags); if (!device_is_registered(&sch->dev)) goto out_unlock; + if (work_pending(&sch->todo_work)) + goto out_unlock; action = sch_get_action(sch); CIO_MSG_EVENT(2, "event: sch 0.%x.%04x, process=%d, action=%d\n", sch->schid.ssid, sch->schid.sch_no, process,