Re: [PATCH][next] net: hinic: fix comparison of a uint16_t type with -1
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From: Dan Carpenter <hidden>
Date: 2017-08-24 09:30:16
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kernel-janitors, lkml
On Thu, Aug 24, 2017 at 09:54:03AM +0100, Colin Ian King wrote:
On 24/08/17 09:48, Aviad Krawczyk wrote:quoted
On 8/23/2017 6:39 PM, Colin King wrote:quoted
From: Colin Ian King <redacted> The comparison of hw_ioctxt.rx_buf_sz_idx == -1 is always false because rx_buf_sz_idx is a uint16_t. Fix this by explicitly casting -1 to uint16_t. Detected by CoverityScan, CID#1454559 ("Operands don't affect result") Signed-off-by: Colin Ian King <redacted> --- drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c b/drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c index 09dec6de8dd5..71e26070fb7f 100644 --- a/drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c +++ b/drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c@@ -352,7 +352,7 @@ static int set_hw_ioctxt(struct hinic_hwdev *hwdev, unsigned int rq_depth, } } - if (hw_ioctxt.rx_buf_sz_idx == -1) + if (hw_ioctxt.rx_buf_sz_idx == (uint16_t)-1) return -EINVAL; hw_ioctxt.sq_depth = ilog2(sq_depth);Many thanks, Colin. I prefer to avoid casting when possible, what do you think about replacing the condition by: if (rx_buf_sz_table[i].sz != HINIC_RX_BUF_SZ) return -EINVAL;Does that work as expected when rx_buf_sz_table[i].sz == -1?
No it doesn't. Please, don't ask rhetorical questions. I have a
toddler and I constantly ask him toddler level questions and it drives
me nuts that all the adults in the room will answer me... "Yes, I
already know that's a cow. I was quizing my son. But thank you!"
Meanwhile I can't resist answering questions myself...
The code looks like this:
drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c
345 hw_ioctxt.rq_depth = ilog2(rq_depth);
346
347 for (i = 0; ; i++) {
348 if ((rx_buf_sz_table[i].sz == HINIC_RX_BUF_SZ) ||
349 (rx_buf_sz_table[i].sz == -1)) {
350 hw_ioctxt.rx_buf_sz_idx = rx_buf_sz_table[i].idx;
351 break;
352 }
353 }
354
355 if (hw_ioctxt.rx_buf_sz_idx == -1)
356 return -EINVAL;
357
The loop doesn't make sense. We are looping through rx_buf_sz_table[]
until we hit 2048 or -1. But 2048 comes first so we always get there
and break.
We may as well replace all that code with:
hw_ioctxt.rx_buf_sz_idx = 11;
Something is very wrong.
regards,
dan carpenter