scsi: ufs: core: Do not hold any lock in ufshcd_hba_stop()

This change is motivated by Bart's suggestion in [1], which enables to
further reduce the SCSI host lock usage in the UFS driver. The reason why
it makes sense, because although the legacy interrupt is disabled by some
but not all ufshcd_hba_stop() callers, it is safe to nest disable_irq()
calls as it checks the irq depth.

[1] https://lore.kernel.org/linux-scsi/[email protected]/

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

Author: avri-altman-sndk

drivers/ufs/core/ufshcd.c

@@ -4768,20 +4768,14 @@ EXPORT_SYMBOL_GPL(ufshcd_make_hba_operational);
  */
 void ufshcd_hba_stop(struct ufs_hba *hba)
 {
-	unsigned long flags;
 	int err;
 
-	/*
-	 * Obtain the host lock to prevent that the controller is disabled
-	 * while the UFS interrupt handler is active on another CPU.
-	 */
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	ufshcd_disable_irq(hba);
 	ufshcd_writel(hba, CONTROLLER_DISABLE,  REG_CONTROLLER_ENABLE);
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
-
 	err = ufshcd_wait_for_register(hba, REG_CONTROLLER_ENABLE,
 					CONTROLLER_ENABLE, CONTROLLER_DISABLE,
 					10, 1);
+	ufshcd_enable_irq(hba);
 	if (err)
 		dev_err(hba->dev, "%s: Controller disable failed\n", __func__);
 }