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| author | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2026-08-03 11:46:27 -0700 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.com> | 2026-08-14 14:46:20 +0200 |
| commit | 225c30812857f47cb42bfd945a15f448f58e82cc (patch) | |
| tree | 13176ad844daa5e6e815d0fa06ad91e074a7fbb6 /scripts | |
| parent | be978be17296d8b304c252933bcb13324173c2d2 (diff) | |
| download | linux-225c30812857f47cb42bfd945a15f448f58e82cc.tar.gz linux-225c30812857f47cb42bfd945a15f448f58e82cc.zip | |
HID: add documentation and Coccinelle script for FF registration race
HID drivers that rely on the HID core to register input devices must
ensure that all private data and capabilities (like force-feedback) are
fully initialized before registration.
When hid_hw_start() is called with HID_CONNECT_HIDINPUT, the input
device is registered immediately. This is racy if the driver attempts to
augment the input device in probe() after starting the hardware.
The correct way to handle this is to use the .input_configured()
callback.
Add documentation and a Coccinelle script to detect and prevent this
anti-pattern.
Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/coccinelle/hid/ff_race.cocci | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/scripts/coccinelle/hid/ff_race.cocci b/scripts/coccinelle/hid/ff_race.cocci new file mode 100644 index 000000000000..479f5d1e3184 --- /dev/null +++ b/scripts/coccinelle/hid/ff_race.cocci @@ -0,0 +1,34 @@ +/// Detect HID drivers that initialize force-feedback after hid_hw_start() +/// when HID_CONNECT_HIDINPUT is used. This is a lifecycle violation as +/// the input device is already registered. +// +// Confidence: High +// Copyright: (C) 2026 Gemini. GPLv2. + +virtual report + +@r@ +identifier probe_fn; +expression hdev, flags; +position p1, p2; +@@ + +probe_fn(struct hid_device *hdev, ...) { + <... + hid_hw_start@p1(hdev, flags) + ... + \(input_ff_create\|input_ff_create_memless\)@p2(...) + ...> +} + +@script:python depends on report@ +p1 << r.p1; +p2 << r.p2; +flags << r.flags; +@@ + +# Check if flags include HID_CONNECT_HIDINPUT (0x01) or HID_CONNECT_DEFAULT (0x0f) +# Note: HID_CONNECT_DEFAULT is 0x0f, HID_CONNECT_HIDINPUT is 0x01 +if "HID_CONNECT_HIDINPUT" in flags or "HID_CONNECT_DEFAULT" in flags: + msg = "WARNING: force-feedback initialized after hid_hw_start() with HID_CONNECT_HIDINPUT. Input device is already registered at this point. Use .input_configured() instead." + coccilib.report.print_report(p2[0], msg) |