On 3/24/20 2:35 PM, Chuhong Yuan wrote:

On Fri, Mar 20, 2020 at 8:01 PM Bartlomiej Zolnierkiewicz
[off-list ref] wrote:

quoted

On 3/10/20 3:35 AM, Chuhong Yuan wrote:

quoted

The driver forgets to free the I/O region in remove and probe
failure.
Add the missed calls to fix it.

Signed-off-by: Chuhong Yuan <redacted>
---
Changes in v3:
  - Revise the commit message.
  - Add an error handler to suit the "goto error" before request_region().
  - Revise the order of operations in remove.

 drivers/video/fbdev/vesafb.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb.c
index a1fe24ea869b..c7bc9ace47d4 100644
--- a/drivers/video/fbdev/vesafb.c
+++ b/drivers/video/fbdev/vesafb.c

@@ -439,7 +439,7 @@ static int vesafb_probe(struct platform_device *dev)
                     "vesafb: abort, cannot ioremap video memory 0x%x @ 0x%lx\n",
                      vesafb_fix.smem_len, vesafb_fix.smem_start);
              err = -EIO;
-             goto err;
+             goto err_release_region;
      }

      printk(KERN_INFO "vesafb: framebuffer at 0x%lx, mapped to 0x%p, "

@@ -458,15 +458,17 @@ static int vesafb_probe(struct platform_device *dev)

      if (fb_alloc_cmap(&info->cmap, 256, 0) < 0) {
              err = -ENOMEM;
-             goto err;
+             goto err_release_region;
      }
      if (register_framebuffer(info)<0) {
              err = -EINVAL;
              fb_dealloc_cmap(&info->cmap);
-             goto err;
+             goto err_release_region;
      }
      fb_info(info, "%s frame buffer device\n", info->fix.id);
      return 0;
+err_release_region:
+     release_region(0x3c0, 32);

This is incorrect.

The cleanup order should be the reverse of the probing order.

Also request_region() return value is not checked by the driver
(there is a comment that it can fail and is optional):

        /* request failure does not faze us, as vgacon probably has this
         * region already (FIXME) */
        request_region(0x3c0, 32, "vesafb");

so what would happen in such case? It seems that unconditionally
doing the release will result in freeing the I/O region owned by
the other driver (vgacon)..

Maybe we can add a field to represent whether the request succeeds?
request_region() returns source *, we can store it and check whether
it is null when
we are going to call release_region().

Yes, this is a preferred approach. 

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

quoted

quoted

 err:
      arch_phys_wc_del(par->wc_cookie);
      if (info->screen_base)

@@ -481,6 +483,7 @@ static int vesafb_remove(struct platform_device *pdev)
      struct fb_info *info = platform_get_drvdata(pdev);

      unregister_framebuffer(info);
+     release_region(0x3c0, 32);
      framebuffer_release(info);

      return 0;

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics