[PATCH AUTOSEL 5.7 181/274] nvme-fc: avoid gcc-10 zero-length-bounds warning

Sasha Levin
2020-06-09T00:46:31Z

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit 3add1d93d9919b6de94aa47900d4904adffbc976 ]

When CONFIG_ARCH_NO_SG_CHAIN is set, op->sgl[0] cannot be dereferenced,
as gcc-10 now points out:

drivers/nvme/host/fc.c: In function 'nvme_fc_init_request':
drivers/nvme/host/fc.c:1774:29: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct scatterlist[0]' [-Wzero-length-bounds]
1774 | op->op.fcp_req.first_sgl = &op->sgl[0];
| ^~~~~~~~~~~
drivers/nvme/host/fc.c:98:21: note: while referencing 'sgl'
98 | struct scatterlist sgl[NVME_INLINE_SG_CNT];
| ^~~

I don't know if this is a legitimate warning or a false-positive.
If this is just a false alarm, the warning is easily suppressed
by interpreting the array as a pointer.

Fixes: b1ae1a238900 ("nvme-fc: Avoid preallocating big SGL for data")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/fc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 7dfc4a2ecf1e..5ef4a84c442a 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -1771,7 +1771,7 @@ nvme_fc_init_request(struct blk_mq_tag_set *set, struct request *rq,
res = __nvme_fc_init_request(ctrl, queue, &op->op, rq, queue->rqcnt++);
if (res)
return res;
- op->op.fcp_req.first_sgl = &op->sgl[0];
+ op->op.fcp_req.first_sgl = op->sgl;
op->op.fcp_req.private = &op->priv[0];
nvme_req(rq)->ctrl = &ctrl->ctrl;
return res;
--
2.25.1