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usb: usbtmc: Fix read_stb function and get_stb ioctl

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commit acb3dac2805d3342ded7dbbd164add32bbfdf21c upstream.

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>
This commit is contained in:
Dave Penkler
2025-05-21 14:16:55 +02:00
committed by Greg Kroah-Hartman
parent b0630d1845
commit 97f5b57eca
1 changed files with 9 additions and 8 deletions
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11
drivers/usb/class/usbtmc.c
View File

@@ -565,14 +565,15 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_file_data *file_data,
rv = usbtmc_get_stb(file_data, &stb); rv = usbtmc_get_stb(file_data, &stb);
if (rv > 0) { if (rv < 0)
srq_asserted = atomic_xchg(&file_data->srq_asserted, return rv;
srq_asserted);
srq_asserted = atomic_xchg(&file_data->srq_asserted, srq_asserted);
if (srq_asserted) if (srq_asserted)
stb |= 0x40; /* Set RQS bit */ stb |= 0x40; /* Set RQS bit */
rv = put_user(stb, (__u8 __user *)arg); rv = put_user(stb, (__u8 __user *)arg);
}
return rv; return rv;
} }
@@ -2201,7 +2202,7 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
case USBTMC_IOCTL_GET_STB: case USBTMC_IOCTL_GET_STB:
retval = usbtmc_get_stb(file_data, &tmp_byte); retval = usbtmc_get_stb(file_data, &tmp_byte);
if (retval > 0) if (!retval)
retval = put_user(tmp_byte, (__u8 __user *)arg); retval = put_user(tmp_byte, (__u8 __user *)arg);
break; break;