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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Paul Burton <paul.burton@imgtec.com>,
        Paul Burton <paul.burton@mips.com>,
        Ralf Baechle <ralf@linux-mips.org>,
        "linux-mips@linux-mips.org" <linux-mips@linux-mips.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.14 87/89] MIPS: WARN_ON invalid DMA cache
 maintenance, not BUG_ON
Thread-Topic: [PATCH AUTOSEL 4.14 87/89] MIPS: WARN_ON invalid DMA cache
 maintenance, not BUG_ON
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Date:   Sun, 2 Sep 2018 13:08:03 +0000
Message-ID: <20180902064918.183387-87-alexander.levin@microsoft.com>
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From: Paul Burton <paul.burton@imgtec.com>

[ 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@mips.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/14623/
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 arch/mips/mm/c-r4k.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index e12dfa48b478..a5893b2cdc0e 100644
--- 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(unsigned long s=
tart, unsigned long end)
 static void r4k_dma_cache_wback_inv(unsigned long addr, unsigned long size=
)
 {
 	/* Catch bad driver code */
-	BUG_ON(size =3D=3D 0);
+	if (WARN_ON(size =3D=3D 0))
+		return;
=20
 	preempt_disable();
 	if (cpu_has_inclusive_pcaches) {
@@ -871,7 +872,8 @@ static void r4k_dma_cache_wback_inv(unsigned long addr,=
 unsigned long size)
 static void r4k_dma_cache_inv(unsigned long addr, unsigned long size)
 {
 	/* Catch bad driver code */
-	BUG_ON(size =3D=3D 0);
+	if (WARN_ON(size =3D=3D 0))
+		return;
=20
 	preempt_disable();
 	if (cpu_has_inclusive_pcaches) {
--=20
2.17.1