lpfc 8.1.9 : Stall eh handlers if resetting while rport blocked

PATCH New James Smart 1 participant 1 message Aug 17, 2006

Subsystems (2)

SCSI Emulex/Broadcom lpfc FC/FCoE SCSI driver

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James Smart

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2006-08-17 15:57 UTC #0 lore raw

PATCH 2/3 lpfc 8.1.9 : Stall eh handlers if resetting while rport blocked

Stall error handler if attempting resets/aborts while an rport is blocked. This avoids device offline scenarios due to errors in the error handler.

Background:
Although the transport is using the scsi_timed_out functionality to restart the timeout if the rport is blocked, if the timeout has already fired before the block occurs, the eh handler still runs and can take the device offline. Ultimately, this window cannot be resolved without significant work in the error handler thread. Christoph noted the first level of these issues when he noted the poor error response handling by the error thread.

We found, under heavy load and error testing, that time window from when the scsi_times_out() adds the io to the queue to when the scsi_error_handler gets around to servicing it, can be in the several seconds range. In most cases, these test conditions are highly unusual, but possible. As a result, we're stalling the error handler in this race window so that we can avoid the device_offline transitions.

Signed-off-by James Smart <[email protected]>

drivers/scsi/lpfc/lpfc_scsi.c +19 -0

@@ -21,6 +21,7 @@
 
 #include <linux/pci.h>
 #include <linux/interrupt.h>
+#include <linux/delay.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_device.h>

@@ -841,6 +842,21 @@ lpfc_queuecommand(struct scsi_cmnd *cmnd
 	return 0;
 }
 
+static void
+lpfc_block_error_handler(struct scsi_cmnd *cmnd)
+{
+	struct Scsi_Host *shost = cmnd->device->host;
+	struct fc_rport *rport = starget_to_rport(scsi_target(cmnd->device));
+
+	spin_lock_irq(shost->host_lock);
+	while (rport->port_state == FC_PORTSTATE_BLOCKED) {
+		spin_unlock_irq(shost->host_lock);
+		msleep(1000);
+		spin_lock_irq(shost->host_lock);
+	}
+	spin_unlock_irq(shost->host_lock);
+	return;
+}
 
 static int
 lpfc_abort_handler(struct scsi_cmnd *cmnd)

@@ -855,6 +871,7 @@ lpfc_abort_handler(struct scsi_cmnd *cmn
 	unsigned int loop_count = 0;
 	int ret = SUCCESS;
 
+	lpfc_block_error_handler(cmnd);
 	spin_lock_irq(shost->host_lock);
 
 	lpfc_cmd = (struct lpfc_scsi_buf *)cmnd->host_scribble;

@@ -957,6 +974,7 @@ lpfc_reset_lun_handler(struct scsi_cmnd 
 	int ret = FAILED;
 	int cnt, loopcnt;
 
+	lpfc_block_error_handler(cmnd);
 	spin_lock_irq(shost->host_lock);
 	/*
 	 * If target is not in a MAPPED state, delay the reset until

@@ -1073,6 +1091,7 @@ lpfc_reset_bus_handler(struct scsi_cmnd 
 	int cnt, loopcnt;
 	struct lpfc_scsi_buf * lpfc_cmd;
 
+	lpfc_block_error_handler(cmnd);
 	spin_lock_irq(shost->host_lock);
 
 	lpfc_cmd = lpfc_get_scsi_buf(phba);