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snd_fasync_helper() updates fasync->on under snd_fasync_lock, and snd_fasync_work_fn() now also evaluates fasync->on under the same lock. snd_kill_fasync() still tests the flag before taking the lock, leaving an unsynchronized read against FASYNC enable/disable updates. Move the enabled-state check into the locked section. Also clear fasync->on under snd_fasync_lock in snd_fasync_free() before unlinking the pending entry. Together with the locked sender-side check, this publishes teardown before flushing the deferred work and prevents a racing sender from requeueing the entry after free has started. Fixes:ef34a0ae7a("ALSA: core: Add async signal helpers") Fixes:8146cd333d("ALSA: core: Fix potential data race at fasync handling") Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com> Link: https://patch.msgid.link/20260506-alsa-core-fasync-on-lock-v1-1-ea48c77d6ca4@gmail.com Signed-off-by: Takashi Iwai <tiwai@suse.de>