linux-kernel - [RFC PATCH] scsi: smartpqi: create module parameters for LUN reset

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Date:   Thu, 21 Jan 2021 14:03:39 -0300
From:   Enzo Matsumiya <ematsumiya@...e.de>
To:     linux-scsi@...r.kernel.org
Cc:     Enzo Matsumiya <ematsumiya@...e.de>,
        Don Brace <don.brace@...rochip.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        storagedev@...rochip.com, linux-kernel@...r.kernel.org
Subject: [RFC PATCH] scsi: smartpqi: create module parameters for LUN reset

Commit c2922f174fa0 ("scsi: smartpqi: fix LUN reset when fw bkgnd thread is hung")
added support for a timeout on LUN resets.

However, when there are 2 or more devices connected to the same
controller and you hot-remove one of them, I/O will stall on the
devices still online for PQI_LUN_RESET_RETRIES * PQI_LUN_RESET_RETRY_INTERVAL_MSECS
miliseconds.

This commit makes those values configurable via module parameters.

Changing the bail out condition on rc in _pqi_device_reset() might be possible,
but could also break the original purpose of commit c2922f174fa0.

Signed-off-by: Enzo Matsumiya <ematsumiya@...e.de>
---
 drivers/scsi/smartpqi/smartpqi_init.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
index c53f456fbd09..9835b2e5b91a 100644
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -157,6 +157,18 @@ module_param_named(hide_vsep,
 MODULE_PARM_DESC(hide_vsep,
 	"Hide the virtual SEP for direct attached drives.");
 
+static int pqi_lun_reset_retries = 3;
+module_param_named(lun_reset_retries,
+	pqi_lun_reset_retries, int, 0644);
+MODULE_PARM_DESC(lun_reset_retries,
+	"Number of retries when resetting a LUN");
+
+static int pqi_lun_reset_tmo_interval = 10000;
+module_param_named(lun_reset_tmo_interval,
+	pqi_lun_reset_tmo_interval, int, 0644);
+MODULE_PARM_DESC(lun_reset_tmo_interval,
+	"LUN reset timeout interval (in miliseconds)");
+
 static char *raid_levels[] = {
 	"RAID-0",
 	"RAID-4",
@@ -5687,8 +5699,6 @@ static int pqi_lun_reset(struct pqi_ctrl_info *ctrl_info,
 
 /* Performs a reset at the LUN level. */
 
-#define PQI_LUN_RESET_RETRIES			3
-#define PQI_LUN_RESET_RETRY_INTERVAL_MSECS	10000
 #define PQI_LUN_RESET_PENDING_IO_TIMEOUT_SECS	120
 
 static int _pqi_device_reset(struct pqi_ctrl_info *ctrl_info,
@@ -5700,9 +5710,9 @@ static int _pqi_device_reset(struct pqi_ctrl_info *ctrl_info,
 
 	for (retries = 0;;) {
 		rc = pqi_lun_reset(ctrl_info, device);
-		if (rc == 0 || ++retries > PQI_LUN_RESET_RETRIES)
+		if (rc == 0 || ++retries > pqi_lun_reset_retries)
 			break;
-		msleep(PQI_LUN_RESET_RETRY_INTERVAL_MSECS);
+		msleep(pqi_lun_reset_tmo_interval);
 	}
 
 	timeout_secs = rc ? PQI_LUN_RESET_PENDING_IO_TIMEOUT_SECS : NO_TIMEOUT;
-- 
2.30.0