Commit 0b09e711 authored by Uma Krishnan's avatar Uma Krishnan Committed by Martin K. Petersen
Browse files

scsi: cxlflash: Schedule asynchronous reset of the host 



A context reset failure indicates the AFU is in a bad state. At present,
when such a situation occurs, no further action is taken. This leaves the
adapter in an unusable state with no recoverable actions.

To avoid this situation, context reset failures will be escalated to a host
reset operation. This will be done asynchronously to allow the acting
thread to return to the user with a failure.

Signed-off-by: default avatarUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent a96851d3

drivers/scsi/cxlflash/common.h

+2 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#ifndef _CXLFLASH_COMMON_H

#define _CXLFLASH_COMMON_H



#include <linux/async.h>

#include <linux/irq_poll.h>

#include <linux/list.h>

#include <linux/rwsem.h>
@@ -144,6 +145,7 @@ struct cxlflash_cfg { 
	bool tmf_active;

	wait_queue_head_t reset_waitq;

	enum cxlflash_state state;

	async_cookie_t async_reset_cookie;

};



struct afu_cmd {

drivers/scsi/cxlflash/main.c

+102 −35
Original line number Diff line number Diff line
@@ -585,6 +585,20 @@ static void free_mem(struct cxlflash_cfg *cfg) 
	}

}



/**

 * cxlflash_reset_sync() - synchronizing point for asynchronous resets

 * @cfg:	Internal structure associated with the host.

 */

static void cxlflash_reset_sync(struct cxlflash_cfg *cfg)

{

	if (cfg->async_reset_cookie == 0)

		return;



	/* Wait until all async calls prior to this cookie have completed */

	async_synchronize_cookie(cfg->async_reset_cookie + 1);

	cfg->async_reset_cookie = 0;

}



/**

 * stop_afu() - stops the AFU command timers and unmaps the MMIO space

 * @cfg:	Internal structure associated with the host.
@@ -601,6 +615,8 @@ static void stop_afu(struct cxlflash_cfg *cfg) 
	int i;



	cancel_work_sync(&cfg->work_q);

	if (!current_is_async())

		cxlflash_reset_sync(cfg);



	if (likely(afu)) {

		while (atomic_read(&afu->cmds_active))
@@ -2004,6 +2020,91 @@ err1: 
	goto out;

}



/**

 * afu_reset() - resets the AFU

 * @cfg:	Internal structure associated with the host.

 *

 * Return: 0 on success, -errno on failure

 */

static int afu_reset(struct cxlflash_cfg *cfg)

{

	struct device *dev = &cfg->dev->dev;

	int rc = 0;



	/* Stop the context before the reset. Since the context is

	 * no longer available restart it after the reset is complete

	 */

	term_afu(cfg);



	rc = init_afu(cfg);



	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);

	return rc;

}



/**

 * drain_ioctls() - wait until all currently executing ioctls have completed

 * @cfg:	Internal structure associated with the host.

 *

 * Obtain write access to read/write semaphore that wraps ioctl

 * handling to 'drain' ioctls currently executing.

 */

static void drain_ioctls(struct cxlflash_cfg *cfg)

{

	down_write(&cfg->ioctl_rwsem);

	up_write(&cfg->ioctl_rwsem);

}



/**

 * cxlflash_async_reset_host() - asynchronous host reset handler

 * @data:	Private data provided while scheduling reset.

 * @cookie:	Cookie that can be used for checkpointing.

 */

static void cxlflash_async_reset_host(void *data, async_cookie_t cookie)

{

	struct cxlflash_cfg *cfg = data;

	struct device *dev = &cfg->dev->dev;

	int rc = 0;



	if (cfg->state != STATE_RESET) {

		dev_dbg(dev, "%s: Not performing a reset, state=%d\n",

			__func__, cfg->state);

		goto out;

	}



	drain_ioctls(cfg);

	cxlflash_mark_contexts_error(cfg);

	rc = afu_reset(cfg);

	if (rc)

		cfg->state = STATE_FAILTERM;

	else

		cfg->state = STATE_NORMAL;

	wake_up_all(&cfg->reset_waitq);



out:

	scsi_unblock_requests(cfg->host);

}



/**

 * cxlflash_schedule_async_reset() - schedule an asynchronous host reset

 * @cfg:	Internal structure associated with the host.

 */

static void cxlflash_schedule_async_reset(struct cxlflash_cfg *cfg)

{

	struct device *dev = &cfg->dev->dev;



	if (cfg->state != STATE_NORMAL) {

		dev_dbg(dev, "%s: Not performing reset state=%d\n",

			__func__, cfg->state);

		return;

	}



	cfg->state = STATE_RESET;

	scsi_block_requests(cfg->host);

	cfg->async_reset_cookie = async_schedule(cxlflash_async_reset_host,

						 cfg);

}



/**

 * cxlflash_afu_sync() - builds and sends an AFU sync command

 * @afu:	AFU associated with the host.
@@ -2085,6 +2186,7 @@ retry: 
		rc = afu->context_reset(hwq);

		if (!rc && ++nretry < 2)

			goto retry;

		cxlflash_schedule_async_reset(cfg);

	}



out:
@@ -2095,41 +2197,6 @@ out: 
	return rc;

}



/**

 * afu_reset() - resets the AFU

 * @cfg:	Internal structure associated with the host.

 *

 * Return: 0 on success, -errno on failure

 */

static int afu_reset(struct cxlflash_cfg *cfg)

{

	struct device *dev = &cfg->dev->dev;

	int rc = 0;



	/* Stop the context before the reset. Since the context is

	 * no longer available restart it after the reset is complete

	 */

	term_afu(cfg);



	rc = init_afu(cfg);



	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);

	return rc;

}



/**

 * drain_ioctls() - wait until all currently executing ioctls have completed

 * @cfg:	Internal structure associated with the host.

 *

 * Obtain write access to read/write semaphore that wraps ioctl

 * handling to 'drain' ioctls currently executing.

 */

static void drain_ioctls(struct cxlflash_cfg *cfg)

{

	down_write(&cfg->ioctl_rwsem);

	up_write(&cfg->ioctl_rwsem);

}



/**

 * cxlflash_eh_device_reset_handler() - reset a single LUN

 * @scp:	SCSI command to send.

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