5.4-stable review patch. If anyone has any objections, please let me know.
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From: Takashi Sakamoto o-takashi@sakamocchi.jp
[ Upstream commit aea3493246c474bc917d124d6fb627663ab6bef0 ]
The ALSA HwDep character device of the firewire-motu driver incorrectly returns EPOLLOUT in poll(2), even though the driver implements no operation for write(2). This misleads userspace applications to believe write() is allowed, potentially resulting in unnecessarily wakeups.
This issue dates back to the driver's initial code added by a commit 71c3797779d3 ("ALSA: firewire-motu: add hwdep interface"), and persisted when POLLOUT was updated to EPOLLOUT by a commit a9a08845e9ac ('vfs: do bulk POLL* -> EPOLL* replacement("").').
This commit fixes the bug.
Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp Link: https://patch.msgid.link/20250829233749.366222-1-o-takashi@sakamocchi.jp Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/firewire/motu/motu-hwdep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/firewire/motu/motu-hwdep.c b/sound/firewire/motu/motu-hwdep.c index 0764a477052a2..5e1254f106bf8 100644 --- a/sound/firewire/motu/motu-hwdep.c +++ b/sound/firewire/motu/motu-hwdep.c @@ -73,7 +73,7 @@ static __poll_t hwdep_poll(struct snd_hwdep *hwdep, struct file *file, events = 0; spin_unlock_irq(&motu->lock);
- return events | EPOLLOUT; + return events; }
static int hwdep_get_info(struct snd_motu *motu, void __user *arg)