[PATCH] iommu: Convert unreachable() to BUG()

[Josh Poimboeuf]

Bare unreachable() should be avoided as it generates undefined behavior,
e.g. falling through to the next function.  Use BUG() instead so the
error is defined.

Fixes the following warnings:

  drivers/iommu/dma-iommu.o: warning: objtool: iommu_dma_sw_msi+0x92: can't find jump dest instruction at .text+0x54d5
  vmlinux.o: warning: objtool: iommu_dma_get_msi_page() falls through to next function __iommu_dma_unmap()

Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Closes: https://lore.kernel.org/314f8809-cd59-479b-97d7-49356bf1c8d1@xxxxxxxxxxxxx
Reported-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Closes: https://lore.kernel.org/5dd1f35e-8ece-43b7-ad6d-86d02d2718f6@paulmck-laptop
Fixes: 6aa63a4ec947 ("iommu: Sort out domain user data")
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 drivers/iommu/dma-iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 7b2734de2ba9..6054d0ab8023 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1753,7 +1753,7 @@ static size_t cookie_msi_granule(const struct iommu_domain *domain)
 	case IOMMU_COOKIE_DMA_MSI:
 		return PAGE_SIZE;
 	default:
-		unreachable();
+		BUG();
 	};
 }
 
@@ -1765,7 +1765,7 @@ static struct list_head *cookie_msi_pages(const struct iommu_domain *domain)
 	case IOMMU_COOKIE_DMA_MSI:
 		return &domain->msi_cookie->msi_page_list;
 	default:
-		unreachable();
+		BUG();
 	};
 }
 
-- 
2.48.1