The usbtmc488_ioctl_read_stb function relied on a positive return from
usbtmc_get_stb to reset the srq condition in the driver. The
USBTMC_IOCTL_GET_STB case tested for a positive return to return the stb
to the user.
Commit: <
cac01bd178d6> ("usb: usbtmc: Fix erroneous get_stb ioctl
error returns") changed the return value of usbtmc_get_stb to 0 on
success instead of returning the value of usb_control_msg which is
positive in the normal case. This change caused the function
usbtmc488_ioctl_read_stb and the USBTMC_IOCTL_GET_STB ioctl to no
longer function correctly.
Change the test in usbtmc488_ioctl_read_stb to test for failure
first and return the failure code immediately.
Change the test for the USBTMC_IOCTL_GET_STB ioctl to test for 0
instead of a positive value.
Fixes:
cac01bd178d6 ("usb: usbtmc: Fix erroneous get_stb ioctl error returns")
Cc: stable@vger.kernel.org
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20250521121656.18174-3-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
rv = usbtmc_get_stb(file_data, &stb);
- if (rv > 0) {
- srq_asserted = atomic_xchg(&file_data->srq_asserted,
- srq_asserted);
- if (srq_asserted)
- stb |= 0x40; /* Set RQS bit */
+ if (rv < 0)
+ return rv;
+
+ srq_asserted = atomic_xchg(&file_data->srq_asserted, srq_asserted);
+ if (srq_asserted)
+ stb |= 0x40; /* Set RQS bit */
+
+ rv = put_user(stb, (__u8 __user *)arg);
- rv = put_user(stb, (__u8 __user *)arg);
- }
return rv;
}
case USBTMC_IOCTL_GET_STB:
retval = usbtmc_get_stb(file_data, &tmp_byte);
- if (retval > 0)
+ if (!retval)
retval = put_user(tmp_byte, (__u8 __user *)arg);
break;