Messages in this thread | | | Date | Thu, 26 Apr 2012 16:31:43 +1000 | From | NeilBrown <> | Subject | Re: [RFC][PATCH 8/8] PM / Sleep: Add user space interface for manipulating wakeup sources |
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On Tue, 24 Apr 2012 23:27:17 +0200 "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl> > Subject: PM / Sleep: Add user space interface for manipulating wakeup sources, v2 > > Android allows user space to manipulate wakelocks using two > sysfs file located in /sys/power/, wake_lock and wake_unlock. > Writing a wakelock name and optionally a timeout to the wake_lock > file causes the wakelock whose name was written to be acquired (it > is created before is necessary), optionally with the given timeout. > Writing the name of a wakelock to wake_unlock causes that wakelock > to be released. > > Implement an analogous interface for user space using wakeup sources. > Add the /sys/power/wake_lock and /sys/power/wake_unlock files > allowing user space to create, activate and deactivate wakeup > sources, such that writing a name and optionally a timeout to > wake_lock causes the wakeup source of that name to be activated, > optionally with the given timeout. If that wakeup source doesn't > exist, it will be created and then activated. Writing a name to > wake_unlock causes the wakeup source of that name, if there is one, > to be deactivated. Wakeup sources created with the help of > wake_lock that haven't been used for more than 5 minutes are garbage > collected and destroyed. Moreover, there can be only WL_NUMBER_LIMIT > wakeup sources created with the help of wake_lock present at a time. > > The data type used to track wakeup sources created by user space is > called "struct wakelock" to indicate the origins of this feature. > > This version of the patch includes an rbtree manipulation fix from John Stultz.
Looks good. Just a couple of minor suggestions.
> +ssize_t pm_show_wakelocks(char *buf, bool show_active) > +{ > + struct rb_node *node; > + struct wakelock *wl; > + char *str = buf; > + char *end = buf + PAGE_SIZE; > + > + mutex_lock(&wakelocks_lock); > + > + for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) { > + bool active; > + > + wl = rb_entry(node, struct wakelock, node); > + spin_lock_irq(&wl->ws.lock); > + active = wl->ws.active; > + spin_unlock_irq(&wl->ws.lock);
I don't think the spin_lock is needed. We are just reading one value and it is either 0 or not. So there is no possibility for any inconsistency. if (wl->ws.active == show_active) ?
> + if (active == show_active) > + str += scnprintf(str, end - str, "%s ", wl->name);
Arg. Extra space on the end of the line!! :-)
I would suggest the entries be terminated by '\n' rather than separate by space. one-item-per-line is much more common in Unix in general. 'grep' allows you to find things more easily etc. while read a do echo $a > wake_unlock done < wake_lock
> + } > + str += scnprintf(str, end - str, "\n"); > + > + mutex_unlock(&wakelocks_lock); > + return (str - buf); > +} > +
Thanks, NeilBrown [unhandled content-type:application/pgp-signature] | |