[PATCH AUTOSEL for 4.9 179/281] powerpc/spufs: Fix coredump of SPU contexts

[Sasha Levin]

From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>

[ Upstream commit 99acc9bede06bbb2662aafff51f5b9e529fa845e ]

If a process dumps core while it has SPU contexts active then we have
code to also dump information about the SPU contexts.

Unfortunately it's been broken for 3 1/2 years, and we didn't notice. In
commit 7b1f4020d0d1 ("spufs: get rid of dump_emit() wrappers") the nread
variable was removed and rc used instead. That means when the loop exits
successfully, rc has the number of bytes read, but it's then used as the
return value for the function, which should return 0 on success.

So fix it by setting rc = 0 before returning in the success case.

Fixes: 7b1f4020d0d1 ("spufs: get rid of dump_emit() wrappers")
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Acked-by: Jeremy Kerr <jk@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 arch/powerpc/platforms/cell/spufs/coredump.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index 85c85eb3e245..b4abf9d5d9e1 100644
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -175,6 +175,8 @@ static int spufs_arch_write_note(struct spu_context *ctx, int i,
 	skip = roundup(cprm->pos - total + sz, 4) - cprm->pos;
 	if (!dump_skip(cprm, skip))
 		goto Eio;
+
+	rc = 0;
 out:
 	free_page((unsigned long)buf);
 	return rc;
-- 
2.14.1