From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH] ACPICA: don't cond_resched() when irq_disabled or in_atomic Date: Thu, 10 Dec 2009 11:09:08 +0100 Message-ID: <20091210100907.GA2446@ucw.cz> References: <1259900760-6424-1-git-send-email-dfeng@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1259900760-6424-1-git-send-email-dfeng@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Xiaotian Feng Cc: lenb@kernel.org, ming.m.lin@intel.com, robert.moore@intel.com, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-acpi@vger.kernel.org On Fri 2009-12-04 12:26:00, Xiaotian Feng wrote: > commit 8bd108d adds preemption point after each opcode parse, then > a sleeping function called from invalid context bug was founded > during suspend/resume stage. this was fixed in commit abe1dfa by > don't cond_resched when irq_disabled. But recent commit 138d156 changes > the behaviour to don't cond_resched when in_atomic. This makes the > sleeping function called from invalid context bug happen again, which > is reported in http://lkml.org/lkml/2009/12/1/371. > > The fix is to cond_sched() only when preemptible, which means not in > irq_disabled or in_atomic. > > @@ -152,7 +152,7 @@ static inline void *acpi_os_acquire_object(acpi_cache_t * cache) > #include > #define ACPI_PREEMPTION_POINT() \ > do { \ > - if (!in_atomic_preempt_off()) \ > + if (preemptible()) \ > cond_resched(); \ > } while (0) Note that this is ugly as hell. It means we have two acpi interpretters in kernel, one for preemptible, one for non-preemptible, with very different behaviour. It would be slightly nicer to pass the "preemptible" info explicitely, as function parameters. It would be even better not to need that difference. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html