[PATCH 4.18 153/158] MIPS: WARN_ON invalid DMA cache maintenance, not BUG_ON

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Burton <paul.burton@xxxxxxxxxx>

[ Upstream commit d4da0e97baea8768b3d66ccef3967bebd50dfc3b ]

If a driver causes DMA cache maintenance with a zero length then we
currently BUG and kill the kernel. As this is a scenario that we may
well be able to recover from, WARN & return in the condition instead.

Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
Acked-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Patchwork: https://patchwork.linux-mips.org/patch/14623/
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/mips/mm/c-r4k.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -835,7 +835,8 @@ static void r4k_flush_icache_user_range(
 static void r4k_dma_cache_wback_inv(unsigned long addr, unsigned long size)
 {
 	/* Catch bad driver code */
-	BUG_ON(size == 0);
+	if (WARN_ON(size == 0))
+		return;
 
 	preempt_disable();
 	if (cpu_has_inclusive_pcaches) {
@@ -871,7 +872,8 @@ static void r4k_dma_cache_wback_inv(unsi
 static void r4k_dma_cache_inv(unsigned long addr, unsigned long size)
 {
 	/* Catch bad driver code */
-	BUG_ON(size == 0);
+	if (WARN_ON(size == 0))
+		return;
 
 	preempt_disable();
 	if (cpu_has_inclusive_pcaches) {