scsi: ufs: core: Remove SCSI host only if added

If host tries to remove ufshcd driver from a UFS device it would cause a
kernel panic if ufshcd_async_scan fails during ufshcd_probe_hba before
adding a SCSI host with scsi_add_host and MCQ is enabled since SCSI host
has been defered after MCQ configuration introduced by commit 0cab402
("scsi: ufs: core: Defer adding host to SCSI if MCQ is supported").

To guarantee that SCSI host is removed only if it has been added, set the
scsi_host_added flag to true after adding a SCSI host and check whether it
is set or not before removing it.

Signed-off-by: Kyoungrul Kim <[email protected]>
Signed-off-by: Minwoo Im <[email protected]>
Link: https://lore.kernel.org/r/20240627085104epcms2p5897a3870ea5c6416aa44f94df6c543d7@epcms2p5
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: KyoungrulKim

drivers/ufs/core/ufshcd.c

@@ -10216,7 +10216,8 @@ void ufshcd_remove(struct ufs_hba *hba)
 	blk_mq_destroy_queue(hba->tmf_queue);
 	blk_put_queue(hba->tmf_queue);
 	blk_mq_free_tag_set(&hba->tmf_tag_set);
-	scsi_remove_host(hba->host);
+	if (hba->scsi_host_added)
+		scsi_remove_host(hba->host);
 	/* disable interrupts */
 	ufshcd_disable_intr(hba, hba->intr_mask);
 	ufshcd_hba_stop(hba);
@@ -10495,6 +10496,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 			dev_err(hba->dev, "scsi_add_host failed\n");
 			goto out_disable;
 		}
+		hba->scsi_host_added = true;
 	}
 
 	hba->tmf_tag_set = (struct blk_mq_tag_set) {
@@ -10577,7 +10579,8 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 free_tmf_tag_set:
 	blk_mq_free_tag_set(&hba->tmf_tag_set);
 out_remove_scsi_host:
-	scsi_remove_host(hba->host);
+	if (hba->scsi_host_added)
+		scsi_remove_host(hba->host);
 out_disable:
 	hba->is_irq_enabled = false;
 	ufshcd_hba_exit(hba);