firmware_loader: Add cancel helper for async requests

request_firmware_nowait() keeps the callback module pinned and holds
a device reference until the firmware work completes.

Callers still have no way to cancel or synchronize the queued callback
before tearing down their driver-private state.

Track scheduled async firmware work in an internal list and add
request_firmware_nowait_cancel(). The helper cancels work matching the
device, callback context and callback function. It cancels work that has
not started yet and waits for an already-running callback to return. If
the request has already completed, it is a no-op.

Keep the existing request_firmware_nowait() lifetime model manual. A
devres-managed variant can be layered on top separately if needed.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260505-alsa-hda-tas2781-fw-callback-teardown-v4-1-e7c4bf930dc8@gmail.com

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/firmware.h b/include/linux/firmware.h
index aae1b85ffc10..0fa3b027f02f 100644
--- a/include/linux/firmware.h
+++ b/include/linux/firmware.h
@@ -110,6 +110,9 @@ int request_firmware_nowait(
 	struct module *module, bool uevent,
 	const char *name, struct device *device, gfp_t gfp, void *context,
 	void (*cont)(const struct firmware *fw, void *context));
+void request_firmware_nowait_cancel(struct device *device, void *context,
+				    void (*cont)(const struct firmware *fw,
+						 void *context));
 int request_firmware_direct(const struct firmware **fw, const char *name,
 			    struct device *device);
 int request_firmware_into_buf(const struct firmware **firmware_p,
@@ -157,6 +160,13 @@ static inline int request_firmware_nowait(
 	return -EINVAL;
 }
 
+static inline void request_firmware_nowait_cancel(struct device *device,
+						  void *context,
+						  void (*cont)(const struct firmware *fw,
+							       void *context))
+{
+}
+
 static inline void release_firmware(const struct firmware *fw)
 {
 }