diff options
| author | Elson Roy Serrao <quic_eserrao@quicinc.com> | 2025-02-06 11:39:50 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-02-14 09:26:25 +0100 |
| commit | 634775a752a86784511018a108f3b530cc3399a7 (patch) | |
| tree | c70a2ffd00a52ff154193115881a8c272fdcd070 | |
| parent | e5644be4079750a0a0a5a7068fd90b97bf6fac55 (diff) | |
usb: roles: set switch registered flag early on
The role switch registration and set_role() can happen in parallel as they
are invoked independent of each other. There is a possibility that a driver
might spend significant amount of time in usb_role_switch_register() API
due to the presence of time intensive operations like component_add()
which operate under common mutex. This leads to a time window after
allocating the switch and before setting the registered flag where the set
role notifications are dropped. Below timeline summarizes this behavior
Thread1 | Thread2
usb_role_switch_register() |
| |
---> allocate switch |
| |
---> component_add() | usb_role_switch_set_role()
| | |
| | --> Drop role notifications
| | since sw->registered
| | flag is not set.
| |
--->Set registered flag.|
To avoid this, set the registered flag early on in the switch register
API.
Fixes: b787a3e78175 ("usb: roles: don't get/set_role() when usb_role_switch is unregistered")
Cc: stable <stable@kernel.org>
Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20250206193950.22421-1-quic_eserrao@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/roles/class.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c index c58a12c147f4..30482d4cf826 100644 --- a/drivers/usb/roles/class.c +++ b/drivers/usb/roles/class.c @@ -387,8 +387,11 @@ usb_role_switch_register(struct device *parent, dev_set_name(&sw->dev, "%s-role-switch", desc->name ? desc->name : dev_name(parent)); + sw->registered = true; + ret = device_register(&sw->dev); if (ret) { + sw->registered = false; put_device(&sw->dev); return ERR_PTR(ret); } @@ -399,8 +402,6 @@ usb_role_switch_register(struct device *parent, dev_warn(&sw->dev, "failed to add component\n"); } - sw->registered = true; - /* TODO: Symlinks for the host port and the device controller. */ return sw; |