Commit acb3dac2 authored by Dave Penkler's avatar Dave Penkler Committed by Greg Kroah-Hartman
Browse files

usb: usbtmc: Fix read_stb function and get_stb ioctl 



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: <cac01bd1> ("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: cac01bd1 ("usb: usbtmc: Fix erroneous get_stb ioctl error returns")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarDave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20250521121656.18174-3-dpenkler@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3335a1bb

drivers/usb/class/usbtmc.c

+9 −8
Original line number Diff line number Diff line
@@ -563,14 +563,15 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_file_data *file_data, 


	rv = usbtmc_get_stb(file_data, &stb);



	if (rv > 0) {

		srq_asserted = atomic_xchg(&file_data->srq_asserted,

					srq_asserted);

	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);

	}



	return rv;



}
@@ -2199,7 +2200,7 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 


	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;