[PATCH] pktcdvd.c: Fix wrong return code when alloc_disk() fails.

[PATCH] pktcdvd.c: Fix wrong return code when alloc_disk() fails.

[Jiecheng Wu]

Function pkt_setup_dev() defined in drivers/block/pktcdvd.c calls alloc_disk(). However, it forgets to set the error return code when alloc_disk() fails. Instead, when alloc_disk() fails, it simply jumps to label 'out_mem' leaving the variable ret unchanged.
---
 drivers/block/pktcdvd.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index b3f83cd..f63fa1f 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2716,8 +2716,10 @@ static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev)
 	pd->write_congestion_off = write_congestion_off;
 
 	disk = alloc_disk(1);
-	if (!disk)
+	if (!disk) {
+		ret = -ENOMEM;
 		goto out_mem;
+	}
 	pd->disk = disk;
 	disk->major = pktdev_major;
 	disk->first_minor = idx;
-- 
2.6.4

Re: [PATCH] pktcdvd.c: Fix wrong return code when alloc_disk() fails.

[Jens Axboe]

On 8/14/18 9:22 PM, Jiecheng Wu wrote:
> Function pkt_setup_dev() defined in drivers/block/pktcdvd.c calls
> alloc_disk(). However, it forgets to set the error return code when
> alloc_disk() fails. Instead, when alloc_disk() fails, it simply jumps
> to label 'out_mem' leaving the variable ret unchanged.

We do init it to -ENOMEM, the problem is that
mempool_init_kmalloc_pool() overwrites it, and any unset jump to error
out after that won't work so well.

So your fix isn't complete, since it won't catch blk_alloc_queue()
failure. The below should do it.


diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index e285413d4a75..6f1d25c1eb64 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2740,6 +2740,7 @@ static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev)
 	pd->write_congestion_on  = write_congestion_on;
 	pd->write_congestion_off = write_congestion_off;
 
+	ret = -ENOMEM;
 	disk = alloc_disk(1);
 	if (!disk)
 		goto out_mem;

-- 
Jens Axboe