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authorOliver Neukum <oneukum@suse.com>2023-12-07 16:26:30 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-12-15 15:52:47 +0300
commit66aad7d8d3ec5a3a8ec2023841bcec2ded5f65c9 (patch)
treeebf32ce8d16e08fafaf559d239405fbaaf22cbc9
parent53b5ff83d89349778bc61e67237f72c5dc6536c2 (diff)
downloadlinux-66aad7d8d3ec5a3a8ec2023841bcec2ded5f65c9.tar.xz
usb: cdc-acm: return correct error code on unsupported break
In ACM support for sending breaks to devices is optional. If a device says that it doenot support sending breaks, the host must respect that. Given the number of optional features providing tty operations for each combination is not practical and errors need to be returned dynamically if unsupported features are requested. In case a device does not support break, we want the tty layer to treat that like it treats drivers that statically cannot support sending a break. It ignores the inability and does nothing. This patch uses EOPNOTSUPP to indicate that. Signed-off-by: Oliver Neukum <oneukum@suse.com> Fixes: 9e98966c7bb94 ("tty: rework break handling") Link: https://lore.kernel.org/r/20231207132639.18250-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/tty_io.c3
-rw-r--r--drivers/usb/class/cdc-acm.c3
2 files changed, 6 insertions, 0 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 06414e43e0b5..96617f9af819 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2489,6 +2489,9 @@ static int send_break(struct tty_struct *tty, unsigned int duration)
if (!retval) {
msleep_interruptible(duration);
retval = tty->ops->break_ctl(tty, 0);
+ } else if (retval == -EOPNOTSUPP) {
+ /* some drivers can tell only dynamically */
+ retval = 0;
}
tty_write_unlock(tty);
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index a1f4e1ead97f..0e7439dba8fe 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -916,6 +916,9 @@ static int acm_tty_break_ctl(struct tty_struct *tty, int state)
struct acm *acm = tty->driver_data;
int retval;
+ if (!(acm->ctrl_caps & USB_CDC_CAP_BRK))
+ return -EOPNOTSUPP;
+
retval = acm_send_break(acm, state ? 0xffff : 0);
if (retval < 0)
dev_dbg(&acm->control->dev,