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Commit 3be8828f authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: core: Avoid that ATA error handling can trigger a kernel hang or oops 



Avoid that the recently introduced call_rcu() call in the SCSI core
triggers a double call_rcu() call.

Reported-by: default avatarNatanael Copa <ncopa@alpinelinux.org>
Reported-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
References: https://bugzilla.kernel.org/show_bug.cgi?id=198861


Fixes: 3bd6f43f ("scsi: core: Ensure that the SCSI error handler gets woken up")
Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Tested-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Cc: Natanael Copa <ncopa@alpinelinux.org>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Alexandre Oliva <oliva@gnu.org>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent fa83e658

drivers/scsi/hosts.c

+0 −3
Original line number Diff line number Diff line
@@ -328,8 +328,6 @@ static void scsi_host_dev_release(struct device *dev) 
	if (shost->work_q)

		destroy_workqueue(shost->work_q);



	destroy_rcu_head(&shost->rcu);



	if (shost->shost_state == SHOST_CREATED) {

		/*

		 * Free the shost_dev device name here if scsi_host_alloc()
@@ -404,7 +402,6 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) 
	INIT_LIST_HEAD(&shost->starved_list);

	init_waitqueue_head(&shost->host_wait);

	mutex_init(&shost->scan_mutex);

	init_rcu_head(&shost->rcu);



	index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);

	if (index < 0)

drivers/scsi/scsi_error.c

+3 −2
Original line number Diff line number Diff line
@@ -223,7 +223,8 @@ static void scsi_eh_reset(struct scsi_cmnd *scmd) 


static void scsi_eh_inc_host_failed(struct rcu_head *head)

{

	struct Scsi_Host *shost = container_of(head, typeof(*shost), rcu);

	struct scsi_cmnd *scmd = container_of(head, typeof(*scmd), rcu);

	struct Scsi_Host *shost = scmd->device->host;

	unsigned long flags;



	spin_lock_irqsave(shost->host_lock, flags);
@@ -259,7 +260,7 @@ void scsi_eh_scmd_add(struct scsi_cmnd *scmd) 
	 * Ensure that all tasks observe the host state change before the

	 * host_failed change.

	 */

	call_rcu(&shost->rcu, scsi_eh_inc_host_failed);

	call_rcu(&scmd->rcu, scsi_eh_inc_host_failed);

}



/**

drivers/scsi/scsi_lib.c

+2 −0
Original line number Diff line number Diff line
@@ -670,6 +670,7 @@ static bool scsi_end_request(struct request *req, blk_status_t error, 
	if (!blk_rq_is_scsi(req)) {

		WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));

		cmd->flags &= ~SCMD_INITIALIZED;

		destroy_rcu_head(&cmd->rcu);

	}



	if (req->mq_ctx) {
@@ -1150,6 +1151,7 @@ static void scsi_initialize_rq(struct request *rq) 
	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);



	scsi_req_init(&cmd->req);

	init_rcu_head(&cmd->rcu);

	cmd->jiffies_at_alloc = jiffies;

	cmd->retries = 0;

}

include/scsi/scsi_cmnd.h

+3 −0
Original line number Diff line number Diff line
@@ -69,6 +69,9 @@ struct scsi_cmnd { 
	struct list_head list;  /* scsi_cmnd participates in queue lists */

	struct list_head eh_entry; /* entry for the host eh_cmd_q */

	struct delayed_work abort_work;



	struct rcu_head rcu;



	int eh_eflags;		/* Used by error handlr */



	/*

include/scsi/scsi_host.h

+0 −2
Original line number Diff line number Diff line
@@ -571,8 +571,6 @@ struct Scsi_Host { 
		struct blk_mq_tag_set	tag_set;

	};



	struct rcu_head rcu;



	atomic_t host_busy;		   /* commands actually active on low-level */

	atomic_t host_blocked;