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Date: Tue, 25 May 2010 06:48:35 +0800 (SGT) From: Jeff Chua <jeff.chua.linux@...il.com> To: Linus Torvalds <torvalds@...ux-foundation.org> cc: Johannes Berg <johannes.berg@...el.com>, Arjan van de Ven <arjan@...ux.intel.com>, "johnstul@...ibm.com" <johnstul@...ibm.com>, Ingo Molnar <mingo@...e.hu>, Andrew Morton <akpm@...ux-foundation.org>, Thomas Gleixner <tglx@...utronix.de>, Intel Linux Wireless <ilw@...ux.intel.com>, "John W. Linville" <linville@...driver.com>, Frans Pop <elendil@...net.nl>, "Chatre, Reinette" <reinette.chatre@...el.com>, lkml <linux-kernel@...r.kernel.org> Subject: Re: Wireless IBSS on Linux-2.6.34 broken by commit 3bbb9ec946428b96657126768f65487a48dd090c On Mon, May 24, 2010 at 10:57 PM, Linus Torvalds <torvalds@...ux-foundation.org> wrote:> > On Mon, 24 May 2010, Jeff Chua wrote: >> + if (timer->slack > -1) >> + else if (time_after(expires, jiffies)) /* auto slack: use 0.4% */ >> expires_limit = expires + (expires - jiffies)/256; > > Please don't reload 'jiffies' twice. It's volatile, and the compiler will > do a crap job of it. Linus, Sorry, didn't know what a jiffies was before, so didn't know about the crap it caused. Now I learned something new. > Also, '0' is a normal number, but '-1' is a rather odd value. Please just > test for non-negative by doing ">= 0" rather than "> -1" Fixed. Below is the patch to fix jiffies and checking for non-negative. Thanks, Jeff --- a/kernel/timer.c.org 2010-05-25 06:05:46.000000000 +0800 +++ a/kernel/timer.c 2010-05-25 06:17:44.000000000 +0800 @@ -748,14 +748,15 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires) { unsigned long expires_limit, mask; + unsigned long now = jiffies; int bit; expires_limit = expires; - if (timer->slack > -1) + if (timer->slack >= 0) expires_limit = expires + timer->slack; - else if (time_after(expires, jiffies)) /* auto slack: use 0.4% */ - expires_limit = expires + (expires - jiffies)/256; + else if (time_after(expires, now)) /* auto slack: use 0.4% */ + expires_limit = expires + (expires - now)/256; mask = expires ^ expires_limit; if (mask == 0) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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