Much better... Just updated #upstream-fixes with the below patch. James just posted to linux-scsi [PATCH] Eliminate error handler overload of the SCSI serial number but as Tejun pointed out, we _completely and entirely_ replace the SCSI error handler apparatus with our own, thereby eliminating any possibility that we would ever read or use cmd->serial_number. Our lock profile is quite a bit improved. Further simplifications and cleanups related to 'done' are possible, but those are kept separate from the change below. commit 23e701e6208191ad103517ae7a700f2dc59ab2ec Author: Jeff Garzik <jeff@xxxxxxxxxx> Date: Wed Nov 17 12:03:58 2010 -0500 [libata] remove SCSI host lock and serial number usage from ata_scsi_queuecmd cmd->serial_number is never tested in any path we reach; therefore we may remove the call to scsi_cmd_get_serial() inside DEF_SCSI_QCMD, the SCSI host_lock acquisition surrounding it, and our own SCSI host_lock unlock+relock cycle. Signed-off-by: Jeff Garzik <jgarzik@xxxxxxxxxx> drivers/ata/libata-scsi.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index 19835d3..66aa4be 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -3166,8 +3166,8 @@ static inline int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, /** * ata_scsi_queuecmd - Issue SCSI cdb to libata-managed device + * @shost: SCSI host of command to be sent * @cmd: SCSI command to be sent - * @done: Completion function, called when command is complete * * In some cases, this function translates SCSI commands into * ATA taskfiles, and queues the taskfiles to be sent to @@ -3177,42 +3177,39 @@ static inline int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, * ATA and ATAPI devices appearing as SCSI devices. * * LOCKING: - * Releases scsi-layer-held lock, and obtains host lock. + * ATA host lock * * RETURNS: * Return value from __ata_scsi_queuecmd() if @cmd can be queued, * 0 otherwise. */ -static int ata_scsi_queuecmd_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *)) +int ata_scsi_queuecmd(struct Scsi_Host *shost, struct scsi_cmnd *cmd) { struct ata_port *ap; struct ata_device *dev; struct scsi_device *scsidev = cmd->device; - struct Scsi_Host *shost = scsidev->host; int rc = 0; + unsigned long irq_flags; ap = ata_shost_to_port(shost); - spin_unlock(shost->host_lock); - spin_lock(ap->lock); + spin_lock_irqsave(ap->lock, irq_flags); ata_scsi_dump_cdb(ap, cmd); dev = ata_scsi_find_dev(ap, scsidev); if (likely(dev)) - rc = __ata_scsi_queuecmd(cmd, done, dev); + rc = __ata_scsi_queuecmd(cmd, cmd->scsi_done, dev); else { cmd->result = (DID_BAD_TARGET << 16); - done(cmd); + cmd->scsi_done(cmd); } - spin_unlock(ap->lock); - spin_lock(shost->host_lock); + spin_unlock_irqrestore(ap->lock, irq_flags); + return rc; } -DEF_SCSI_QCMD(ata_scsi_queuecmd) - /** * ata_scsi_simulate - simulate SCSI command on ATA device * @dev: the target device -- 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