From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org (Andrew Morton) Date: Mon, 31 Jan 2011 22:38:59 -0800 Subject: [PATCH v4 1/4] drivers: hwspinlock: add framework In-Reply-To: References: <1296470024-26854-1-git-send-email-ohad@wizery.com> <1296470024-26854-2-git-send-email-ohad@wizery.com> <20110131153831.dca62146.akpm@linux-foundation.org> Message-ID: <20110131223859.27169db0.akpm@linux-foundation.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 1 Feb 2011 08:20:13 +0200 Ohad Ben-Cohen wrote: > On Tue, Feb 1, 2011 at 1:38 AM, Andrew Morton wrote: > > It's a little irritating having two hwspinlock.h's. > > hwspinlock_internal.h wold be a conventional approach. __But it's not a > > big deal. > ... > > >> +/** > >> + * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit > >> + * @hwlock: the hwspinlock to be locked > >> + * @timeout: timeout value in jiffies > > > > hm, why in jiffies? > > > > The problem here is that lazy programmers will use > > > > __ __ __ __hwspin_lock_timeout(lock, 10, ...) > > > > and their code will work happily with HZ=100 but will explode with HZ=1000. > > > > IOW, this interface *requires* that all callers perform a > > seconds-to-jiffies conversion before calling hwspin_lock_timeout(). __So > > why not reduce their effort and their ability to make mistakes by > > defining the API to take seconds? > > I considered that, but then decided to use jiffies in order to be > consistent with wait_event_timeout/schedule_timeout (although I don't > return the remaining jiffies in case the lock is taken before the > timeout elapses), and also to allow user-selected granularity. > > But I do kind of like the idea of not using jiffies. We can probably > even move to msecs, since anyway this is an error condition, and > people who needs a quick check should just use the trylock() version. > > I'll do a quick respin of the patches with that and the > hwspinlock_internal.h comment above. OK.. The patch series looks OK to me. But there isn't a lot of point in me putting them into my tree. Maybe Tony or Russell or Greg can grab them if they like the look of it all?