scsi: scsi_debug: Simplify command handling

Simplify command handling by moving struct sdebug_defer into the private
SCSI command data instead of allocating it separately. The only functional
change is that aborting a SCSI command now fails and is retried at a later
time if the completion handler can't be cancelled.

See also commit 1107c7b ("scsi: scsi_debug: Dynamically allocate
sdebug_queued_cmd").

Signed-off-by: Bart Van Assche <[email protected]>
Signed-off-by: John Garry <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>

Author: bvanassche

drivers/scsi/scsi_debug.c

@@ -300,11 +300,6 @@ struct tape_block {
 
 #define SDEB_XA_NOT_IN_USE XA_MARK_1
 
-static struct kmem_cache *queued_cmd_cache;
-
-#define TO_QUEUED_CMD(scmd)  ((void *)(scmd)->host_scribble)
-#define ASSIGN_QUEUED_CMD(scmnd, qc) { (scmnd)->host_scribble = (void *) qc; }
-
 /* Zone types (zbcr05 table 25) */
 enum sdebug_z_type {
 	ZBC_ZTYPE_CNV	= 0x1,
@@ -460,17 +455,9 @@ struct sdebug_defer {
 	enum sdeb_defer_type defer_t;
 };
 
-
-struct sdebug_queued_cmd {
-	/* corresponding bit set in in_use_bm[] in owning struct sdebug_queue
-	 * instance indicates this slot is in use.
-	 */
-	struct sdebug_defer sd_dp;
-	struct scsi_cmnd *scmd;
-};
-
 struct sdebug_scsi_cmd {
 	spinlock_t   lock;
+	struct sdebug_defer sd_dp;
 };
 
 static atomic_t sdebug_cmnd_count;   /* number of incoming commands */
@@ -636,8 +623,6 @@ static int sdebug_add_store(void);
 static void sdebug_erase_store(int idx, struct sdeb_store_info *sip);
 static void sdebug_erase_all_stores(bool apart_from_first);
 
-static void sdebug_free_queued_cmd(struct sdebug_queued_cmd *sqcp);
-
 /*
  * The following are overflow arrays for cdbs that "hit" the same index in
  * the opcode_info_arr array. The most time sensitive (or commonly used) cdb
@@ -6333,10 +6318,10 @@ static u32 get_tag(struct scsi_cmnd *cmnd)
 /* Queued (deferred) command completions converge here. */
 static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp)
 {
-	struct sdebug_queued_cmd *sqcp = container_of(sd_dp, struct sdebug_queued_cmd, sd_dp);
+	struct sdebug_scsi_cmd *sdsc = container_of(sd_dp,
+					typeof(*sdsc), sd_dp);
+	struct scsi_cmnd *scp = (struct scsi_cmnd *)sdsc - 1;
 	unsigned long flags;
-	struct scsi_cmnd *scp = sqcp->scmd;
-	struct sdebug_scsi_cmd *sdsc;
 	bool aborted;
 
 	if (sdebug_statistics) {
@@ -6347,27 +6332,23 @@ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp)
 
 	if (!scp) {
 		pr_err("scmd=NULL\n");
-		goto out;
+		return;
 	}
 
-	sdsc = scsi_cmd_priv(scp);
 	spin_lock_irqsave(&sdsc->lock, flags);
 	aborted = sd_dp->aborted;
 	if (unlikely(aborted))
 		sd_dp->aborted = false;
-	ASSIGN_QUEUED_CMD(scp, NULL);
 
 	spin_unlock_irqrestore(&sdsc->lock, flags);
 
 	if (aborted) {
 		pr_info("bypassing scsi_done() due to aborted cmd, kicking-off EH\n");
 		blk_abort_request(scsi_cmd_to_rq(scp));
-		goto out;
+		return;
 	}
 
 	scsi_done(scp); /* callback to mid level */
-out:
-	sdebug_free_queued_cmd(sqcp);
 }
 
 /* When high resolution timer goes off this function is called. */
@@ -6674,10 +6655,15 @@ static void scsi_debug_sdev_destroy(struct scsi_device *sdp)
 	sdp->hostdata = NULL;
 }
 
-/* Returns true if we require the queued memory to be freed by the caller. */
-static bool stop_qc_helper(struct sdebug_defer *sd_dp,
-			   enum sdeb_defer_type defer_t)
+/* Returns true if it is safe to complete @cmnd. */
+static bool scsi_debug_stop_cmnd(struct scsi_cmnd *cmnd)
 {
+	struct sdebug_scsi_cmd *sdsc = scsi_cmd_priv(cmnd);
+	struct sdebug_defer *sd_dp = &sdsc->sd_dp;
+	enum sdeb_defer_type defer_t = READ_ONCE(sd_dp->defer_t);
+
+	lockdep_assert_held(&sdsc->lock);
+
 	if (defer_t == SDEB_DEFER_HRT) {
 		int res = hrtimer_try_to_cancel(&sd_dp->hrt);
 
@@ -6702,28 +6688,6 @@ static bool stop_qc_helper(struct sdebug_defer *sd_dp,
 	return false;
 }
 
-
-static bool scsi_debug_stop_cmnd(struct scsi_cmnd *cmnd)
-{
-	enum sdeb_defer_type l_defer_t;
-	struct sdebug_defer *sd_dp;
-	struct sdebug_scsi_cmd *sdsc = scsi_cmd_priv(cmnd);
-	struct sdebug_queued_cmd *sqcp = TO_QUEUED_CMD(cmnd);
-
-	lockdep_assert_held(&sdsc->lock);
-
-	if (!sqcp)
-		return false;
-	sd_dp = &sqcp->sd_dp;
-	l_defer_t = READ_ONCE(sd_dp->defer_t);
-	ASSIGN_QUEUED_CMD(cmnd, NULL);
-
-	if (stop_qc_helper(sd_dp, l_defer_t))
-		sdebug_free_queued_cmd(sqcp);
-
-	return true;
-}
-
 /*
  * Called from scsi_debug_abort() only, which is for timed-out cmd.
  */
@@ -7106,33 +7070,6 @@ static bool inject_on_this_cmd(void)
 
 #define INCLUSIVE_TIMING_MAX_NS 1000000		/* 1 millisecond */
 
-
-void sdebug_free_queued_cmd(struct sdebug_queued_cmd *sqcp)
-{
-	if (sqcp)
-		kmem_cache_free(queued_cmd_cache, sqcp);
-}
-
-static struct sdebug_queued_cmd *sdebug_alloc_queued_cmd(struct scsi_cmnd *scmd)
-{
-	struct sdebug_queued_cmd *sqcp;
-	struct sdebug_defer *sd_dp;
-
-	sqcp = kmem_cache_zalloc(queued_cmd_cache, GFP_ATOMIC);
-	if (!sqcp)
-		return NULL;
-
-	sd_dp = &sqcp->sd_dp;
-
-	hrtimer_init(&sd_dp->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
-	sd_dp->hrt.function = sdebug_q_cmd_hrt_complete;
-	INIT_WORK(&sd_dp->ew.work, sdebug_q_cmd_wq_complete);
-
-	sqcp->scmd = scmd;
-
-	return sqcp;
-}
-
 /* Complete the processing of the thread that queued a SCSI command to this
  * driver. It either completes the command by calling cmnd_done() or
  * schedules a hr timer or work queue then returns 0. Returns
@@ -7149,7 +7086,6 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
 	struct sdebug_scsi_cmd *sdsc = scsi_cmd_priv(cmnd);
 	unsigned long flags;
 	u64 ns_from_boot = 0;
-	struct sdebug_queued_cmd *sqcp;
 	struct scsi_device *sdp;
 	struct sdebug_defer *sd_dp;
 
@@ -7181,12 +7117,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
 		}
 	}
 
-	sqcp = sdebug_alloc_queued_cmd(cmnd);
-	if (!sqcp) {
-		pr_err("%s no alloc\n", __func__);
-		return SCSI_MLQUEUE_HOST_BUSY;
-	}
-	sd_dp = &sqcp->sd_dp;
+	sd_dp = &sdsc->sd_dp;
 
 	if (polled || (ndelay > 0 && ndelay < INCLUSIVE_TIMING_MAX_NS))
 		ns_from_boot = ktime_get_boottime_ns();
@@ -7234,7 +7165,6 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
 
 				if (kt <= d) {	/* elapsed duration >= kt */
 					/* call scsi_done() from this thread */
-					sdebug_free_queued_cmd(sqcp);
 					scsi_done(cmnd);
 					return 0;
 				}
@@ -7247,13 +7177,11 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
 		if (polled) {
 			spin_lock_irqsave(&sdsc->lock, flags);
 			sd_dp->cmpl_ts = ktime_add(ns_to_ktime(ns_from_boot), kt);
-			ASSIGN_QUEUED_CMD(cmnd, sqcp);
 			WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_POLL);
 			spin_unlock_irqrestore(&sdsc->lock, flags);
 		} else {
 			/* schedule the invocation of scsi_done() for a later time */
 			spin_lock_irqsave(&sdsc->lock, flags);
-			ASSIGN_QUEUED_CMD(cmnd, sqcp);
 			WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_HRT);
 			hrtimer_start(&sd_dp->hrt, kt, HRTIMER_MODE_REL_PINNED);
 			/*
@@ -7277,13 +7205,11 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
 			sd_dp->issuing_cpu = raw_smp_processor_id();
 		if (polled) {
 			spin_lock_irqsave(&sdsc->lock, flags);
-			ASSIGN_QUEUED_CMD(cmnd, sqcp);
 			sd_dp->cmpl_ts = ns_to_ktime(ns_from_boot);
 			WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_POLL);
 			spin_unlock_irqrestore(&sdsc->lock, flags);
 		} else {
 			spin_lock_irqsave(&sdsc->lock, flags);
-			ASSIGN_QUEUED_CMD(cmnd, sqcp);
 			WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_WQ);
 			schedule_work(&sd_dp->ew.work);
 			spin_unlock_irqrestore(&sdsc->lock, flags);
@@ -8650,12 +8576,6 @@ static int __init scsi_debug_init(void)
 	hosts_to_add = sdebug_add_host;
 	sdebug_add_host = 0;
 
-	queued_cmd_cache = KMEM_CACHE(sdebug_queued_cmd, SLAB_HWCACHE_ALIGN);
-	if (!queued_cmd_cache) {
-		ret = -ENOMEM;
-		goto driver_unreg;
-	}
-
 	sdebug_debugfs_root = debugfs_create_dir("scsi_debug", NULL);
 	if (IS_ERR_OR_NULL(sdebug_debugfs_root))
 		pr_info("%s: failed to create initial debugfs directory\n", __func__);
@@ -8682,8 +8602,6 @@ static int __init scsi_debug_init(void)
 
 	return 0;
 
-driver_unreg:
-	driver_unregister(&sdebug_driverfs_driver);
 bus_unreg:
 	bus_unregister(&pseudo_lld_bus);
 dev_unreg:
@@ -8699,7 +8617,6 @@ static void __exit scsi_debug_exit(void)
 
 	for (; k; k--)
 		sdebug_do_remove_host(true);
-	kmem_cache_destroy(queued_cmd_cache);
 	driver_unregister(&sdebug_driverfs_driver);
 	bus_unregister(&pseudo_lld_bus);
 	root_device_unregister(pseudo_primary);
@@ -9083,7 +9000,6 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
 	struct sdebug_defer *sd_dp;
 	u32 unique_tag = blk_mq_unique_tag(rq);
 	u16 hwq = blk_mq_unique_tag_to_hwq(unique_tag);
-	struct sdebug_queued_cmd *sqcp;
 	unsigned long flags;
 	int queue_num = data->queue_num;
 	ktime_t time;
@@ -9099,13 +9015,7 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
 	time = ktime_get_boottime();
 
 	spin_lock_irqsave(&sdsc->lock, flags);
-	sqcp = TO_QUEUED_CMD(cmd);
-	if (!sqcp) {
-		spin_unlock_irqrestore(&sdsc->lock, flags);
-		return true;
-	}
-
-	sd_dp = &sqcp->sd_dp;
+	sd_dp = &sdsc->sd_dp;
 	if (READ_ONCE(sd_dp->defer_t) != SDEB_DEFER_POLL) {
 		spin_unlock_irqrestore(&sdsc->lock, flags);
 		return true;
@@ -9115,8 +9025,6 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
 		spin_unlock_irqrestore(&sdsc->lock, flags);
 		return true;
 	}
-
-	ASSIGN_QUEUED_CMD(cmd, NULL);
 	spin_unlock_irqrestore(&sdsc->lock, flags);
 
 	if (sdebug_statistics) {
@@ -9125,8 +9033,6 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
 			atomic_inc(&sdebug_miss_cpus);
 	}
 
-	sdebug_free_queued_cmd(sqcp);
-
 	scsi_done(cmd); /* callback to mid level */
 	(*data->num_entries)++;
 	return true;
@@ -9441,8 +9347,12 @@ static int scsi_debug_queuecommand(struct Scsi_Host *shost,
 static int sdebug_init_cmd_priv(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 {
 	struct sdebug_scsi_cmd *sdsc = scsi_cmd_priv(cmd);
+	struct sdebug_defer *sd_dp = &sdsc->sd_dp;
 
 	spin_lock_init(&sdsc->lock);
+	hrtimer_init(&sd_dp->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
+	sd_dp->hrt.function = sdebug_q_cmd_hrt_complete;
+	INIT_WORK(&sd_dp->ew.work, sdebug_q_cmd_wq_complete);
 
 	return 0;
 }