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authorAlan Stern <stern@rowland.harvard.edu>2012-02-17 16:25:08 -0500
committerJames Bottomley <JBottomley@Parallels.com>2012-02-18 08:54:19 -0600
commitfea6d607e154cf96ab22254ccb48addfd43d4cb5 (patch)
treeb52995114d637ffa3ddfaa681d5ca2407151d057 /drivers/scsi/device_handler
parent267a6ad4aefaafbde607804c60945bcf97f91c1b (diff)
downloadblackbird-op-linux-fea6d607e154cf96ab22254ccb48addfd43d4cb5.tar.gz
blackbird-op-linux-fea6d607e154cf96ab22254ccb48addfd43d4cb5.zip
[SCSI] scsi_pm: Fix bug in the SCSI power management handler
This patch (as1520) fixes a bug in the SCSI layer's power management implementation. LUN scanning can be carried out asynchronously in do_scan_async(), and sd uses an asynchronous thread for the time-consuming parts of disk probing in sd_probe_async(). Currently nothing coordinates these async threads with system sleep transitions; they can and do attempt to continue scanning/probing SCSI devices even after the host adapter has been suspended. As one might expect, the outcome is not ideal. This is what the "prepare" stage of system suspend was created for. After the prepare callback has been called for a host, target, or device, drivers are not allowed to register any children underneath them. Currently the SCSI prepare callback is not implemented; this patch rectifies that omission. For SCSI hosts, the prepare routine calls scsi_complete_async_scans() to wait until async scanning is finished. It might be slightly more efficient to wait only until the host in question has been scanned, but there's currently no way to do that. Besides, during a sleep transition we will ultimately have to wait until all the host scanning has finished anyway. For SCSI devices, the prepare routine calls async_synchronize_full() to wait until sd probing is finished. The routine does nothing for SCSI targets, because asynchronous target scanning is done only as part of host scanning. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: <stable@kernel.org> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi/device_handler')
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