On Tue, 2010-07-27 at 17:21 -0500, James Bottomley wrote: > On Thu, 2010-06-17 at 10:41 -0400, Alan Stern wrote: > > This patch (as1398b) adds runtime PM support to the SCSI layer. Only > > the machanism is provided; use of it is up to the various high-level > > drivers, and the patch doesn't change any of them. Except for sg -- > > the patch expicitly prevents a device from being runtime-suspended > > while its sg device file is open. > > > > The implementation is simplistic. In general, hosts and targets are > > automatically suspended when all their children are asleep, but for > > them the runtime-suspend code doesn't actually do anything. (A host's > > runtime PM status is propagated up the device tree, though, so a > > runtime-PM-aware lower-level driver could power down the host adapter > > hardware at the appropriate times.) There are comments indicating > > where a transport class might be notified or some other hooks added. > > > > LUNs are runtime-suspended by calling the drivers' existing suspend > > handlers (and likewise for runtime-resume). Somewhat arbitrarily, the > > implementation delays for 100 ms before suspending an eligible LUN. > > This is because there typically are occasions during bootup when the > > same device file is opened and closed several times in quick > > succession. > > > > The way this all works is that the SCSI core increments a device's > > PM-usage count when it is registered. If a high-level driver does > > nothing then the device will not be eligible for runtime-suspend > > because of the elevated usage count. If a high-level driver wants to > > use runtime PM then it can call scsi_autopm_put_device() in its probe > > routine to decrement the usage count and scsi_autopm_get_device() in > > its remove routine to restore the original count. > > > > Hosts, targets, and LUNs are not suspended while they are being probed > > or removed, or while the error handler is running. In fact, a fairly > > large part of the patch consists of code to make sure that things > > aren't suspended at such times. > > > > Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > > > > --- > > > > Version 2 changes: > > > > Rebase to apply on top of the revised 1/3 patch. > > > > Add a KERN_ERR log level to the SCSI_LOG_ERROR_RECOVERY > > call, as recommended by checkpatch. > > > > Incidentally, although I didn't mention it before, this patch assumes > > that the 7-part series beginning here: > > > > http://marc.info/?l=linux-scsi&m=127551091314515&w=2 > > > > has been merged. > > > > > > Index: usb-2.6/drivers/scsi/scsi_priv.h > > =================================================================== > > --- usb-2.6.orig/drivers/scsi/scsi_priv.h > > +++ usb-2.6/drivers/scsi/scsi_priv.h > > @@ -7,6 +7,7 @@ struct request_queue; > > struct request; > > struct scsi_cmnd; > > struct scsi_device; > > +struct scsi_target; > > struct scsi_host_template; > > struct Scsi_Host; > > struct scsi_nl_hdr; > > @@ -147,7 +148,18 @@ static inline void scsi_netlink_exit(voi > > /* scsi_pm.c */ > > #ifdef CONFIG_PM_OPS > > extern const struct dev_pm_ops scsi_bus_pm_ops; > > +#ifdef CONFIG_PM_RUNTIME > > +extern void scsi_autopm_get_target(struct scsi_target *); > > +extern void scsi_autopm_put_target(struct scsi_target *); > > +extern int scsi_autopm_get_host(struct Scsi_Host *); > > +extern void scsi_autopm_put_host(struct Scsi_Host *); > > #else > > +static inline void scsi_autopm_get_target(struct scsi_target *) {} > > +static inline void scsi_autopm_put_target(struct scsi_target *) {} > > +static inline int scsi_autopm_get_host(struct Scsi_Host *) { return 0; } > > +static inline void scsi_autopm_put_host(struct Scsi_Host *) {} > > You didn't compile this, did you? The compiler gets distinctly annoyed > to see an inline function with no actual variable for the argument ... > > I fixed up this and the one in scsi_device.h Since there were actually 3 relevant config variations, this turned out to be the final fix. James --- diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h index 53010a3..026295e 100644 --- a/drivers/scsi/scsi_priv.h +++ b/drivers/scsi/scsi_priv.h @@ -148,20 +148,20 @@ static inline void scsi_netlink_exit(void) {} /* scsi_pm.c */ #ifdef CONFIG_PM_OPS extern const struct dev_pm_ops scsi_bus_pm_ops; +#else /* CONFIG_PM_OPS */ +#define scsi_bus_pm_ops (*NULL) +#endif #ifdef CONFIG_PM_RUNTIME extern void scsi_autopm_get_target(struct scsi_target *); extern void scsi_autopm_put_target(struct scsi_target *); extern int scsi_autopm_get_host(struct Scsi_Host *); extern void scsi_autopm_put_host(struct Scsi_Host *); #else -static inline void scsi_autopm_get_target(struct scsi_target *) {} -static inline void scsi_autopm_put_target(struct scsi_target *) {} -static inline int scsi_autopm_get_host(struct Scsi_Host *) { return 0; } -static inline void scsi_autopm_put_host(struct Scsi_Host *) {} +static inline void scsi_autopm_get_target(struct scsi_target *t) {} +static inline void scsi_autopm_put_target(struct scsi_target *t) {} +static inline int scsi_autopm_get_host(struct Scsi_Host *h) { return 0; } +static inline void scsi_autopm_put_host(struct Scsi_Host *h) {} #endif /* CONFIG_PM_RUNTIME */ -#else /* CONFIG_PM_OPS */ -#define scsi_bus_pm_ops (*NULL) -#endif /* * internal scsi timeout functions: for use by mid-layer and transport diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 7df2eff..50cb34f 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -385,8 +385,8 @@ extern int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd, extern int scsi_autopm_get_device(struct scsi_device *); extern void scsi_autopm_put_device(struct scsi_device *); #else -static inline int scsi_autopm_get_device(struct scsi_device *) { return 0; } -static inline void scsi_autopm_put_device(struct scsi_device *) {} +static inline int scsi_autopm_get_device(struct scsi_device *d) { return 0; } +static inline void scsi_autopm_put_device(struct scsi_device *d) {} #endif /* CONFIG_PM_RUNTIME */ static inline int __must_check scsi_device_reprobe(struct scsi_device *sdev) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
