Messages in this thread | | | Date | Thu, 06 Mar 2003 10:10:55 -0800 (PST) | Subject | Re: [patch] "HT scheduler", sched-2.5.63-B3 | From | "David S. Miller" <> |
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From: Linus Torvalds <torvalds@transmeta.com> Date: Thu, 6 Mar 2003 10:20:42 -0800 (PST)
Note that "in_interrupt()" will also trigger for callers that call from bh-atomic regions as well as actual BH handlers. Which is correct - they are both "interrupt contexts" as far as most users should be concerned.
The unix domain case may well be bh-atomic, I haven't looked at the code. I'm pretty much certain that the TCP case _will_ be BH-atomic, even for loopback.
David?
Unix sockets use non-BH locks, there are no software interrupts involved in AF_UNIX processing so no need to protect against them.
The actual wakeup comes from the socket callbacks, we use the default data_ready() which is:
void sock_def_readable(struct sock *sk, int len) { read_lock(&sk->callback_lock); if (sk->sleep && waitqueue_active(sk->sleep)) wake_up_interruptible(sk->sleep); sk_wake_async(sk,1,POLL_IN); read_unlock(&sk->callback_lock); }
And for write wakeups Unix uses it's own, which is:
static void unix_write_space(struct sock *sk) { read_lock(&sk->callback_lock); if (unix_writable(sk)) { if (sk->sleep && waitqueue_active(sk->sleep)) wake_up_interruptible(sk->sleep); sk_wake_async(sk, 2, POLL_OUT); } read_unlock(&sk->callback_lock); }
So, to reiterate, no BH locking is used by AF_UNIX. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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