Re: ANNOUNCE: big change in PCM kernel API

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Sat Jan 08 2000 - 17:45:33 EST


> ALSA has already the same behaviour (also for OSS emulation) and the
> inode lock is dropped on write (to tell you the truth I'd have preferred
> that sys_write transfer the inode->i_sem handling entirely to
> f_op->write, but probably the efficiency impact of the double down/up is
> small)
>
> I'm not sure to understand the second part (and one sleeping on a write
> locks out the other), can you rephrase that?

If you don't drop the lock then what can occur is what you already avoided
by dropping the lock

Task1
                sys_write(sound_fd, buf, len)
                driver write
                driver does blocking wait for 10 seconds

Task2
                sys_write
                        sleep in inode lock for 10 seconds
                

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