Re: [PATCH v2] vhost: fix unchecked return value

[Maxime Coquelin]

On 7/1/22 09:11, Hu, Jiayu wrote:

Hi Maxime,

-----Original Message-----
From: Maxime Coquelin <maxime.coque...@redhat.com>
Sent: Thursday, June 30, 2022 5:57 PM
To: Hu, Jiayu <jiayu...@intel.com>; dev@dpdk.org
Cc: Xia, Chenbo <chenbo....@intel.com>; sta...@dpdk.org; David Marchand
<david.march...@redhat.com>
Subject: Re: [PATCH v2] vhost: fix unchecked return value



On 6/29/22 11:07, Jiayu Hu wrote:

This patch checks the return value of rte_dma_info_get() called in
rte_vhost_async_dma_configure().

Coverity issue: 379066
Fixes: 53d3f4778c1d ("vhost: integrate dmadev in asynchronous
data-path")
Cc: sta...@dpdk.org

Signed-off-by: Jiayu Hu <jiayu...@intel.com>
Reviewed-by: Chenbo Xia <chenbo....@intel.com>
---
v2:
- add cc stable tag
---
   lib/vhost/vhost.c | 6 +++++-
   1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c index
b14521e4d1..70c04c036e 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1868,7 +1868,11 @@ rte_vhost_async_dma_configure(int16_t

dma_id, uint16_t vchan_id)

                return -1;
        }

-       rte_dma_info_get(dma_id, &info);
+       if (rte_dma_info_get(dma_id, &info) != 0) {
+               VHOST_LOG_CONFIG(ERR, "Fail to get DMA %d

information.\n", dma_id);

+               return -1;
+       }
+
        if (vchan_id >= info.max_vchans) {
                VHOST_LOG_CONFIG(ERR, "Invalid DMA %d vChannel %u.\n",

dma_id, vchan_id);

                return -1;

The patch itself looks good, but rte_vhost_async_dma_configure() should be
protected by a lock, as concurrent calls of this function would lead to
undefined behavior.

This function is expected to be called only once. Is there any use case to 
cause it
called concurrently?

Ok, so what about:

================================================================
static bool dma_configured:

int
rte_vhost_async_dma_configure(int16_t dma_id, uint16_t vchan_id)
{
        struct rte_dma_info info;
        void *pkts_cmpl_flag_addr;
        uint16_t max_desc;

        if (dma_configured)
                return -1;

        dma_configured = true;

================================================================

If this is called only once, this should be OK. ;)


Maxime

Thanks,
Jiayu

Can you cook something?

David, is that the issue you mentioned me this week or was it another one?

Thanks,
Maxime