From 3c31b52f96f7b559d950b16113c0f68c72a1985e Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 10 Apr 2014 15:30:35 -0700 Subject: scsi: async sd resume async_schedule() sd resume work to allow disks and other devices to resume in parallel. This moves the entirety of scsi_device resume to an async context to ensure that scsi_device_resume() remains ordered with respect to the completion of the start/stop command. For the duration of the resume, new command submissions (that do not originate from the scsi-core) will be deferred (BLKPREP_DEFER). It adds a new ASYNC_DOMAIN_EXCLUSIVE(scsi_sd_pm_domain) as a container of these operations. Like scsi_sd_probe_domain it is flushed at sd_remove() time to ensure async ops do not continue past the end-of-life of the sdev. The implementation explicitly refrains from reusing scsi_sd_probe_domain directly for this purpose as it is flushed at the end of dpm_resume(), potentially defeating some of the benefit. Given sdevs are quiesced it is permissible for these resume operations to bleed past the async_synchronize_full() calls made by the driver core. We defer the resolution of which pm callback to call until scsi_dev_type_{suspend|resume} time and guarantee that the callback parameter is never NULL. With this in place the type of resume operation is encoded in the async function identifier. There is a concern that async resume could trigger PSU overload. In the enterprise, storage enclosures enforce staggered spin-up regardless of what the kernel does making async scanning safe by default. Outside of that context a user can disable asynchronous scanning via a kernel command line or CONFIG_SCSI_SCAN_ASYNC. Honor that setting when deciding whether to do resume asynchronously. Inspired by Todd's analysis and initial proposal [2]: https://01.org/suspendresume/blogs/tebrandt/2013/hard-disk-resume-optimization-simpler-approach Cc: Len Brown Cc: Phillip Susi [alan: bug fix and clean up suggestion] Acked-by: Alan Stern Suggested-by: Todd Brandt [djbw: kick all resume work to the async queue] Signed-off-by: Dan Williams --- drivers/scsi/scsi_pm.c | 128 ++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 99 insertions(+), 29 deletions(-) (limited to 'drivers/scsi/scsi_pm.c') diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c index 001e9ceda4c3..7454498c4091 100644 --- a/drivers/scsi/scsi_pm.c +++ b/drivers/scsi/scsi_pm.c @@ -18,35 +18,77 @@ #ifdef CONFIG_PM_SLEEP -static int scsi_dev_type_suspend(struct device *dev, int (*cb)(struct device *)) +static int do_scsi_suspend(struct device *dev, const struct dev_pm_ops *pm) { + return pm && pm->suspend ? pm->suspend(dev) : 0; +} + +static int do_scsi_freeze(struct device *dev, const struct dev_pm_ops *pm) +{ + return pm && pm->freeze ? pm->freeze(dev) : 0; +} + +static int do_scsi_poweroff(struct device *dev, const struct dev_pm_ops *pm) +{ + return pm && pm->poweroff ? pm->poweroff(dev) : 0; +} + +static int do_scsi_resume(struct device *dev, const struct dev_pm_ops *pm) +{ + return pm && pm->resume ? pm->resume(dev) : 0; +} + +static int do_scsi_thaw(struct device *dev, const struct dev_pm_ops *pm) +{ + return pm && pm->thaw ? pm->thaw(dev) : 0; +} + +static int do_scsi_restore(struct device *dev, const struct dev_pm_ops *pm) +{ + return pm && pm->restore ? pm->restore(dev) : 0; +} + +static int scsi_dev_type_suspend(struct device *dev, + int (*cb)(struct device *, const struct dev_pm_ops *)) +{ + const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; int err; + /* flush pending in-flight resume operations, suspend is synchronous */ + async_synchronize_full_domain(&scsi_sd_pm_domain); + err = scsi_device_quiesce(to_scsi_device(dev)); if (err == 0) { - if (cb) { - err = cb(dev); - if (err) - scsi_device_resume(to_scsi_device(dev)); - } + err = cb(dev, pm); + if (err) + scsi_device_resume(to_scsi_device(dev)); } dev_dbg(dev, "scsi suspend: %d\n", err); return err; } -static int scsi_dev_type_resume(struct device *dev, int (*cb)(struct device *)) +static int scsi_dev_type_resume(struct device *dev, + int (*cb)(struct device *, const struct dev_pm_ops *)) { + const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; int err = 0; - if (cb) - err = cb(dev); + err = cb(dev, pm); scsi_device_resume(to_scsi_device(dev)); dev_dbg(dev, "scsi resume: %d\n", err); + + if (err == 0) { + pm_runtime_disable(dev); + pm_runtime_set_active(dev); + pm_runtime_enable(dev); + } + return err; } static int -scsi_bus_suspend_common(struct device *dev, int (*cb)(struct device *)) +scsi_bus_suspend_common(struct device *dev, + int (*cb)(struct device *, const struct dev_pm_ops *)) { int err = 0; @@ -66,20 +108,54 @@ scsi_bus_suspend_common(struct device *dev, int (*cb)(struct device *)) return err; } -static int -scsi_bus_resume_common(struct device *dev, int (*cb)(struct device *)) +static void async_sdev_resume(void *dev, async_cookie_t cookie) { - int err = 0; + scsi_dev_type_resume(dev, do_scsi_resume); +} - if (scsi_is_sdev_device(dev)) - err = scsi_dev_type_resume(dev, cb); +static void async_sdev_thaw(void *dev, async_cookie_t cookie) +{ + scsi_dev_type_resume(dev, do_scsi_thaw); +} - if (err == 0) { +static void async_sdev_restore(void *dev, async_cookie_t cookie) +{ + scsi_dev_type_resume(dev, do_scsi_restore); +} + +static int scsi_bus_resume_common(struct device *dev, + int (*cb)(struct device *, const struct dev_pm_ops *)) +{ + async_func_t fn; + + if (!scsi_is_sdev_device(dev)) + fn = NULL; + else if (cb == do_scsi_resume) + fn = async_sdev_resume; + else if (cb == do_scsi_thaw) + fn = async_sdev_thaw; + else if (cb == do_scsi_restore) + fn = async_sdev_restore; + else + fn = NULL; + + if (fn) { + async_schedule_domain(fn, dev, &scsi_sd_pm_domain); + + /* + * If a user has disabled async probing a likely reason + * is due to a storage enclosure that does not inject + * staggered spin-ups. For safety, make resume + * synchronous as well in that case. + */ + if (strncmp(scsi_scan_type, "async", 5) != 0) + async_synchronize_full_domain(&scsi_sd_pm_domain); + } else { pm_runtime_disable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); } - return err; + return 0; } static int scsi_bus_prepare(struct device *dev) @@ -97,38 +173,32 @@ static int scsi_bus_prepare(struct device *dev) static int scsi_bus_suspend(struct device *dev) { - const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; - return scsi_bus_suspend_common(dev, pm ? pm->suspend : NULL); + return scsi_bus_suspend_common(dev, do_scsi_suspend); } static int scsi_bus_resume(struct device *dev) { - const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; - return scsi_bus_resume_common(dev, pm ? pm->resume : NULL); + return scsi_bus_resume_common(dev, do_scsi_resume); } static int scsi_bus_freeze(struct device *dev) { - const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; - return scsi_bus_suspend_common(dev, pm ? pm->freeze : NULL); + return scsi_bus_suspend_common(dev, do_scsi_freeze); } static int scsi_bus_thaw(struct device *dev) { - const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; - return scsi_bus_resume_common(dev, pm ? pm->thaw : NULL); + return scsi_bus_resume_common(dev, do_scsi_thaw); } static int scsi_bus_poweroff(struct device *dev) { - const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; - return scsi_bus_suspend_common(dev, pm ? pm->poweroff : NULL); + return scsi_bus_suspend_common(dev, do_scsi_poweroff); } static int scsi_bus_restore(struct device *dev) { - const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; - return scsi_bus_resume_common(dev, pm ? pm->restore : NULL); + return scsi_bus_resume_common(dev, do_scsi_restore); } #else /* CONFIG_PM_SLEEP */ -- cgit v1.2.3-59-g8ed1b