>> Let's quote the example from rubini & corbet of the sbull block device
>> driver. The request function ends like so:
>
> defective locking in a driver is no excuse to pamper over it with
> recusrive shite.
Arjan is a little too harsh here, but on the principle I happen
to agree, because I worked with systems which allow recursive locks.
They very often cover up for programmer's lack of basic understanding.
Worse, sometimes even experienced programmers can do poorly.
I ran into the latter cathegory of code when fixing so-called
"presto" in Solaris (now replaced by Encore-originated code).
Normal spinlocks are not without problems, in particular people
tend to write:
void urb_rm_priv_locked(struct urb *) {
......
}
void urb_rm_priv(struct urb *u) {
spin_lock_irqsave();
urb_rm_prin_locked(u);
spin_unlock_irqrestore();
}
Which eats a stack frame. We make this tradeoff on purpose,
as a lesser evil.
BTW, I do not see Linus and his leutenants rebuking the onslaught
of recursive ingenuity in this thread. Ignoring the hogwash,
or waiting and watching?
-- Pete
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This archive was generated by hypermail 2b29 : Fri May 23 2003 - 22:00:37 EST