1 files changed, 52 insertions, 35 deletions

diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
index 640c3a2641ef..be7522ae02a4 100644
--- a/drivers/scsi/cxlflash/superpipe.c
+++ b/drivers/scsi/cxlflash/superpipe.c
@@ -808,11 +808,56 @@ static void init_context(struct ctx_info *ctxi, struct cxlflash_cfg *cfg,
 	ctxi->file = file;
 	ctxi->initialized = true;
 	mutex_init(&ctxi->mutex);
+	kref_init(&ctxi->kref);
 	INIT_LIST_HEAD(&ctxi->luns);
 	INIT_LIST_HEAD(&ctxi->list); /* initialize for list_empty() */
 }
 
 /**
+ * remove_context() - context kref release handler
+ * @kref:	Kernel reference associated with context to be removed.
+ *
+ * When a context no longer has any references it can safely be removed
+ * from global access and destroyed. Note that it is assumed the thread
+ * relinquishing access to the context holds its mutex.
+ */
+static void remove_context(struct kref *kref)
+{
+	struct ctx_info *ctxi = container_of(kref, struct ctx_info, kref);
+	struct cxlflash_cfg *cfg = ctxi->cfg;
+	int lfd;
+	u64 ctxid = DECODE_CTXID(ctxi->ctxid);
+
+	/* Remove context from table/error list */
+	WARN_ON(!mutex_is_locked(&ctxi->mutex));
+	ctxi->unavail = true;
+	mutex_unlock(&ctxi->mutex);
+	mutex_lock(&cfg->ctx_tbl_list_mutex);
+	mutex_lock(&ctxi->mutex);
+
+	if (!list_empty(&ctxi->list))
+		list_del(&ctxi->list);
+	cfg->ctx_tbl[ctxid] = NULL;
+	mutex_unlock(&cfg->ctx_tbl_list_mutex);
+	mutex_unlock(&ctxi->mutex);
+
+	/* Context now completely uncoupled/unreachable */
+	lfd = ctxi->lfd;
+	destroy_context(cfg, ctxi);
+
+	/*
+	 * As a last step, clean up external resources when not
+	 * already on an external cleanup thread, i.e.: close(adap_fd).
+	 *
+	 * NOTE: this will free up the context from the CXL services,
+	 * allowing it to dole out the same context_id on a future
+	 * (or even currently in-flight) disk_attach operation.
+	 */
+	if (lfd != -1)
+		sys_close(lfd);
+}
+
+/**
  * _cxlflash_disk_detach() - detaches a LUN from a context
  * @sdev:	SCSI device associated with LUN.
  * @ctxi:	Context owning resources.
@@ -837,7 +882,6 @@ static int _cxlflash_disk_detach(struct scsi_device *sdev,
 
 	int i;
 	int rc = 0;
-	int lfd;
 	u64 ctxid = DECODE_CTXID(detach->context_id),
 	    rctxid = detach->context_id;
 
@@ -879,40 +923,12 @@ static int _cxlflash_disk_detach(struct scsi_device *sdev,
 			break;
 		}
 
-	/* Tear down context following last LUN cleanup */
-	if (list_empty(&ctxi->luns)) {
-		ctxi->unavail = true;
-		mutex_unlock(&ctxi->mutex);
-		mutex_lock(&cfg->ctx_tbl_list_mutex);
-		mutex_lock(&ctxi->mutex);
-
-		/* Might not have been in error list so conditionally remove */
-		if (!list_empty(&ctxi->list))
-			list_del(&ctxi->list);
-		cfg->ctx_tbl[ctxid] = NULL;
-		mutex_unlock(&cfg->ctx_tbl_list_mutex);
-		mutex_unlock(&ctxi->mutex);
-
-		lfd = ctxi->lfd;
-		destroy_context(cfg, ctxi);
-		ctxi = NULL;
-		put_ctx = false;
-
-		/*
-		 * As a last step, clean up external resources when not
-		 * already on an external cleanup thread, i.e.: close(adap_fd).
-		 *
-		 * NOTE: this will free up the context from the CXL services,
-		 * allowing it to dole out the same context_id on a future
-		 * (or even currently in-flight) disk_attach operation.
-		 */
-		if (lfd != -1)
-			sys_close(lfd);
-	}
-
-	/* Release the sdev reference that bound this LUN to the context */
+	/*
+	 * Release the context reference and the sdev reference that
+	 * bound this LUN to the context.
+	 */
+	put_ctx = !kref_put(&ctxi->kref, remove_context);
 	scsi_device_put(sdev);
-
 out:
 	if (put_ctx)
 		put_context(ctxi);
@@ -1369,10 +1385,11 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
 	lun_access->lli = lli;
 	lun_access->sdev = sdev;
 
-	/* Non-NULL context indicates reuse */
+	/* Non-NULL context indicates reuse (another context reference) */
 	if (ctxi) {
 		dev_dbg(dev, "%s: Reusing context for LUN! (%016llX)\n",
 			__func__, rctxid);
+		kref_get(&ctxi->kref);
 		list_add(&lun_access->list, &ctxi->luns);
 		fd = ctxi->lfd;
 		goto out_attach;