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ALSA: line6: hwdep: add support for O_NONBLOCK opening mode 

Currently line6 hwdep interface ignores O_NONBLOCK flag when
opening device and it renders it somewhat useless when using poll.

Check for O_NONBLOCK flag when opening device and don't block read()
if it is set.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Link: https://lore.kernel.org/r/20200502193120.79115-2-anarsoul@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Vasily Khoruzhick 2020-05-02 12:31:19 -07:00 committed by Takashi Iwai
parent 7f0d5053c5
commit 5c2d0de544
2 changed files with 5 additions and 0 deletions
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4
sound/usb/line6/driver.c
View File

@ -550,6 +550,7 @@ static int line6_hwdep_open(struct snd_hwdep *hw, struct file *file)
/* NOTE: hwdep layer provides atomicity here */
line6->messages.active = 1;
line6->messages.nonblock = file->f_flags & O_NONBLOCK ? 1 : 0;
return 0;
}
@ -579,6 +580,9 @@ line6_hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count,
while (kfifo_len(&line6->messages.fifo) == 0) {
mutex_unlock(&line6->messages.read_lock);
if (line6->messages.nonblock)
return -EAGAIN;
rv = wait_event_interruptible(
line6->messages.wait_queue,
kfifo_len(&line6->messages.fifo) != 0);

1
sound/usb/line6/driver.h
View File

@ -163,6 +163,7 @@ struct usb_line6 {
struct mutex read_lock;
wait_queue_head_t wait_queue;
unsigned int active:1;
unsigned int nonblock:1;
STRUCT_KFIFO_REC_2(LINE6_BUFSIZE_LISTEN * LINE6_RAW_MESSAGES_MAXCOUNT)
fifo;
} messages;