Re: [PATCH] media: v4l: cadence: Fix how unsued lanes are handled in 'csi2rx_start()'

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Le 16/09/2019 à 08:28, Dan Carpenter a écrit :
On Fri, Sep 13, 2019 at 09:57:09AM +0200, Maxime Ripard wrote:
Hi Christophe,

On Thu, Sep 12, 2019 at 10:44:50PM +0200, Christophe JAILLET wrote:
The 2nd parameter of 'find_first_zero_bit()' is a number of bits, not of
bytes. So use 'BITS_PER_LONG' instead of 'sizeof(lanes_used)'.

Fixes: 1fc3b37f34f6 ("media: v4l: cadence: Add Cadence MIPI-CSI2 RX driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
This patch is purely speculative. Using BITS_PER_LONG looks logical to me,
but I'm not 100% sure that it is what is expected here. 'csi2rx->max_lanes'
could also be a good candidate.
Yeah, csi2rx->max_lanes would make more sense in that context. Could
you resend a new version?
This is sort of unrelated, but for Smatch purposes the csi2rx->max_lanes
comes from the firmware in csi2rx_parse_dt() and it could be any u8
value.

Hi Dan,

not sure to follow you.

csi2rx_probe()
  --> csi2rx_get_resources()
     -->  ...
          dev_cfg = readl(csi2rx->base + CSI2RX_DEVICE_CFG_REG);
          ...
          csi2rx->max_lanes = dev_cfg & 7;
          if (csi2rx->max_lanes > CSI2RX_LANES_MAX) {
             dev_err(&pdev->dev, "Invalid number of lanes: %u\n",
                     csi2rx->max_lanes);
             return -EINVAL;
          }

So I guess, that we can trust max_lanes because of the 'if (... > CSI2RX_LANES_MAX)' check.

Did I miss something?


I sort of wish that people would write code which was known to be
correct just from reading the kernel code, without looking at the
firmware...  I guess I could mark v4l2_fwnode_endpoint_parse() as always
giving us valid data, but that still wouldn't tell us what the valid
data is.  It's hard to know the right answer from a static analysis
point of view.

regards,
dan carpenter






[Index of Archives]     [Linux Input]     [Video for Linux]     [Gstreamer Embedded]     [Mplayer Users]     [Linux USB Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [Yosemite Backpacking]

  Powered by Linux