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Commit 018d1dc9 authored by Matthew R. Ochs's avatar Matthew R. Ochs Committed by James Bottomley
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cxlflash: Fix to avoid stall while waiting on TMF 



Borrowing the TMF waitq's spinlock causes a stall condition when
waiting for the TMF to complete. To remedy, introduce our own spin
lock to serialize TMF and use the appropriate wait services.

Also add a timeout while waiting for a TMF completion. When a TMF
times out, report back a failure such that a bigger hammer reset
can occur.

Signed-off-by: default avatarMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: default avatarManoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: default avatarBrian King <brking@linux.vnet.ibm.com>
Reviewed-by: default avatarTomas Henzl <thenzl@redhat.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Odin.com>
parent 4392ba49

drivers/scsi/cxlflash/common.h

+1 −0
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ struct cxlflash_cfg { 
	struct list_head lluns; /* list of llun_info structs */



	wait_queue_head_t tmf_waitq;

	spinlock_t tmf_slock;

	bool tmf_active;

	wait_queue_head_t reset_waitq;

	enum cxlflash_state state;

drivers/scsi/cxlflash/main.c

+33 −22
Original line number Diff line number Diff line
@@ -249,11 +249,10 @@ static void cmd_complete(struct afu_cmd *cmd) 
		scp->scsi_done(scp);



		if (cmd_is_tmf) {

			spin_lock_irqsave(&cfg->tmf_waitq.lock, lock_flags);

			spin_lock_irqsave(&cfg->tmf_slock, lock_flags);

			cfg->tmf_active = false;

			wake_up_all_locked(&cfg->tmf_waitq);

			spin_unlock_irqrestore(&cfg->tmf_waitq.lock,

					       lock_flags);

			spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);

		}

	} else

		complete(&cmd->cevent);
@@ -420,6 +419,7 @@ static int send_tmf(struct afu *afu, struct scsi_cmnd *scp, u64 tmfcmd) 
	struct device *dev = &cfg->dev->dev;

	ulong lock_flags;

	int rc = 0;

	ulong to;



	cmd = cmd_checkout(afu);

	if (unlikely(!cmd)) {
@@ -428,15 +428,15 @@ static int send_tmf(struct afu *afu, struct scsi_cmnd *scp, u64 tmfcmd) 
		goto out;

	}



	/* If a Task Management Function is active, do not send one more.

	 */

	spin_lock_irqsave(&cfg->tmf_waitq.lock, lock_flags);

	/* When Task Management Function is active do not send another */

	spin_lock_irqsave(&cfg->tmf_slock, lock_flags);

	if (cfg->tmf_active)

		wait_event_interruptible_locked_irq(cfg->tmf_waitq,

						    !cfg->tmf_active);

		wait_event_interruptible_lock_irq(cfg->tmf_waitq,

						  !cfg->tmf_active,

						  cfg->tmf_slock);

	cfg->tmf_active = true;

	cmd->cmd_tmf = true;

	spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);

	spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);



	cmd->rcb.ctx_id = afu->ctx_hndl;

	cmd->rcb.port_sel = port_sel;
@@ -457,15 +457,24 @@ static int send_tmf(struct afu *afu, struct scsi_cmnd *scp, u64 tmfcmd) 
	rc = send_cmd(afu, cmd);

	if (unlikely(rc)) {

		cmd_checkin(cmd);

		spin_lock_irqsave(&cfg->tmf_waitq.lock, lock_flags);

		spin_lock_irqsave(&cfg->tmf_slock, lock_flags);

		cfg->tmf_active = false;

		spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);

		spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);

		goto out;

	}



	spin_lock_irqsave(&cfg->tmf_waitq.lock, lock_flags);

	wait_event_interruptible_locked_irq(cfg->tmf_waitq, !cfg->tmf_active);

	spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);

	spin_lock_irqsave(&cfg->tmf_slock, lock_flags);

	to = msecs_to_jiffies(5000);

	to = wait_event_interruptible_lock_irq_timeout(cfg->tmf_waitq,

						       !cfg->tmf_active,

						       cfg->tmf_slock,

						       to);

	if (!to) {

		cfg->tmf_active = false;

		dev_err(dev, "%s: TMF timed out!\n", __func__);

		rc = -1;

	}

	spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);

out:

	return rc;

}
@@ -512,16 +521,17 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) 
			    get_unaligned_be32(&((u32 *)scp->cmnd)[2]),

			    get_unaligned_be32(&((u32 *)scp->cmnd)[3]));



	/* If a Task Management Function is active, wait for it to complete

	/*

	 * If a Task Management Function is active, wait for it to complete

	 * before continuing with regular commands.

	 */

	spin_lock_irqsave(&cfg->tmf_waitq.lock, lock_flags);

	spin_lock_irqsave(&cfg->tmf_slock, lock_flags);

	if (cfg->tmf_active) {

		spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);

		spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);

		rc = SCSI_MLQUEUE_HOST_BUSY;

		goto out;

	}

	spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);

	spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);



	switch (cfg->state) {

	case STATE_RESET:
@@ -713,11 +723,12 @@ static void cxlflash_remove(struct pci_dev *pdev) 
	/* If a Task Management Function is active, wait for it to complete

	 * before continuing with remove.

	 */

	spin_lock_irqsave(&cfg->tmf_waitq.lock, lock_flags);

	spin_lock_irqsave(&cfg->tmf_slock, lock_flags);

	if (cfg->tmf_active)

		wait_event_interruptible_locked_irq(cfg->tmf_waitq,

						    !cfg->tmf_active);

	spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);

		wait_event_interruptible_lock_irq(cfg->tmf_waitq,

						  !cfg->tmf_active,

						  cfg->tmf_slock);

	spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);



	cfg->state = STATE_FAILTERM;

	cxlflash_stop_term_user_contexts(cfg);