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authorTejun Heo <htejun@gmail.com>2006-02-10 15:10:48 +0900
committerJeff Garzik <jgarzik@pobox.com>2006-02-10 06:50:46 -0500
commitf29841e08fa20a7f2c8bc1b70306975299c66ee7 (patch)
treec2f6c87cf79fbd36ec49ea3c2247a382da5d75cc /drivers
parent341963b909a01d2f38d86f5db8dd1f8c80bd6dbf (diff)
[PATCH] libata: implement ata_scsi_timed_out()
Implement ata_scsi_timed_out(), to be used as scsi_host_template->eh_timed_out callback for all libata drivers. Without this function, the following race exists. If a qc completes after SCSI timer expires but before libata EH kicks in, the qc gets completed but the scsicmd still gets passed to libata EH resulting in ->eng_timeout invocation with NULL qc, which none is handling properly. This patch makes sure that scmd and qc share the same lifetime. Original idea from Jeff Garzik <jgarzik@pobox.com>. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/scsi/libata-core.c1
-rw-r--r--drivers/scsi/libata-scsi.c41
2 files changed, 42 insertions, 0 deletions
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 977a53dd167..d53e0bce2be 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -4913,6 +4913,7 @@ EXPORT_SYMBOL_GPL(ata_ratelimit);
EXPORT_SYMBOL_GPL(ata_busy_sleep);
EXPORT_SYMBOL_GPL(ata_scsi_ioctl);
EXPORT_SYMBOL_GPL(ata_scsi_queuecmd);
+EXPORT_SYMBOL_GPL(ata_scsi_timed_out);
EXPORT_SYMBOL_GPL(ata_scsi_error);
EXPORT_SYMBOL_GPL(ata_scsi_slave_config);
EXPORT_SYMBOL_GPL(ata_scsi_release);
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 1df468eb2bf..d67cc2fb569 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -717,6 +717,47 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
}
/**
+ * ata_scsi_timed_out - SCSI layer time out callback
+ * @cmd: timed out SCSI command
+ *
+ * Handles SCSI layer timeout. We race with normal completion of
+ * the qc for @cmd. If the qc is already gone, we lose and let
+ * the scsi command finish (EH_HANDLED). Otherwise, the qc has
+ * timed out and EH should be invoked. Prevent ata_qc_complete()
+ * from finishing it by setting EH_SCHEDULED and return
+ * EH_NOT_HANDLED.
+ *
+ * LOCKING:
+ * Called from timer context
+ *
+ * RETURNS:
+ * EH_HANDLED or EH_NOT_HANDLED
+ */
+enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
+{
+ struct Scsi_Host *host = cmd->device->host;
+ struct ata_port *ap = (struct ata_port *) &host->hostdata[0];
+ unsigned long flags;
+ struct ata_queued_cmd *qc;
+ enum scsi_eh_timer_return ret = EH_HANDLED;
+
+ DPRINTK("ENTER\n");
+
+ spin_lock_irqsave(&ap->host_set->lock, flags);
+ qc = ata_qc_from_tag(ap, ap->active_tag);
+ if (qc) {
+ assert(qc->scsicmd == cmd);
+ qc->flags |= ATA_QCFLAG_EH_SCHEDULED;
+ qc->err_mask |= AC_ERR_TIMEOUT;
+ ret = EH_NOT_HANDLED;
+ }
+ spin_unlock_irqrestore(&ap->host_set->lock, flags);
+
+ DPRINTK("EXIT, ret=%d\n", ret);
+ return ret;
+}
+
+/**
* ata_scsi_error - SCSI layer error handler callback
* @host: SCSI host on which error occurred
*