On 27/01/15 17:20, Hartley Sweeten wrote:
On Tuesday, January 27, 2015 8:59 AM, Ian Abbott wrote:
On 27/01/15 15:50, Ian Abbott wrote:
`do_cmd_ioctl()` in "comedi_fops.c" handles the `COMEDI_CMD` ioctl.
This returns `-EAGAIN` if it has copied a modified `struct comedi_cmd`
back to user-space. (This occurs when the low-level Comedi driver's
`do_cmdtest()` handler returns non-zero to indicate a problem with the
contents of the `struct comedi_cmd`, or when the `struct comedi_cmd` has
the `CMDF_BOGUS` flag set.)
`compat_cmd()` in "comedi_compat32.c" handles the 32-bit compatible
version of the `COMEDI_CMD` ioctl. Currently, it never copies a 32-bit
compatible version of `struct comedi_cmd` back to user-space, which is
at odds with the way the regular `COMEDI_CMD` ioctl is handled. To fix
it, change `compat_cmd()` to copy a 32-bit compatible version of the
`struct comedi_cmd` back to user-space when the main ioctl handler
returns `-EAGAIN`.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
drivers/staging/comedi/comedi_compat32.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/comedi/comedi_compat32.c b/drivers/staging/comedi/comedi_compat32.c
index 5a4c74f..2440c60 100644
--- a/drivers/staging/comedi/comedi_compat32.c
+++ b/drivers/staging/comedi/comedi_compat32.c
@@ -262,7 +262,8 @@ static int compat_cmd(struct file *file, unsigned long arg)
{
struct comedi_cmd __user *cmd;
struct comedi32_cmd_struct __user *cmd32;
- int rc;
+ long rc;
+ int err;
Gah! That change in type of the 'rc' variable resulted from me changing
the order of the patches in the series. It still works, but looks a bit
out of place. Should I post an updated version without this niggle?
Please fix it. I does look strange. Actually, the last patch looks strange.
The "normal" return type in the kernel is an 'int'. As you mention in the
commit message: "The `unlocked_ioctl` and `compat_ioctl` file operations
are both defined to return a `long` (I don't know why)." It seems cleaner
to just have all the static functions return an int and just have
comedi_compat_ioctl() return the long value. Maybe just add a comment
why...
My 2 cents...
Yes, on reflection I think passing through the `long` return value is
just pandering to an abomination that should be ignored. I'll post a v2
series with the above niggle fixed and the final patch dropped.
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=-
-=( Web: http://www.mev.co.uk/ )=-
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