Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 23 Jul 2002 20:05:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 23 Jul 2002 20:05:38 -0400 Received: from mx1.elte.hu ([157.181.1.137]:2774 "HELO mx1.elte.hu") by vger.kernel.org with SMTP id ; Tue, 23 Jul 2002 20:05:37 -0400 Date: Wed, 24 Jul 2002 02:07:42 +0200 (CEST) From: Ingo Molnar Reply-To: Ingo Molnar To: Linus Torvalds Cc: george anzinger , Zwane Mwaikambo , Trond Myklebust , Linux Kernel Subject: Re: [patch] irqlock patch -G3. [was Re: odd memory corruption in 2.5.27?] In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3108 Lines: 104 On Tue, 23 Jul 2002, Linus Torvalds wrote: > /* BIG comment about what we're doing. */ > /* We're dropping the spinlock, but we remain non-preemptable */ > __raw_spin_unlock(..); > > and then later on, when preemptability is over, we do > > local_irq_enable(); > preempt_enable(); > > so that we _clearly_ mark out the region where we must not re-schedule. agreed, this is much nicer. i removed the spin_unlock_no_resched() define, and modified the slab.c fix (and the other spin_unlock_no_resched() places) to be more verbose about what they do. we still have preempt_enable_no_resched() - that is legitimately needed in a number of cases - i've added comments to make its usage clear. these cleanups are in the -G5 patch: http://redhat.com/~mingo/remove-irqlock-patches/remove-irqlock-2.5.27-G5 i've test-booted BK-curr + G5, CONFIG_SMP, CONFIG_PREEMPT and CONFIG_DEBUG_IRQ_SCHEDULE kernel on an SMP box, it works fine. Ingo Changes in -G3: - slab.c needs to spin_unlock_no_resched(), instead of spin_unlock(). (It also has to check for preemption in the right spot.) This should fix the memory corruption. - irq_exit() needs to run softirqs if interrupts not active - in the previous patch it ran them when preempt_count() was 0, which is incorrect. - spinlock macros are updated to enable preemption after enabling interrupts. Besides avoiding false positive warnings, this also - fork.c has to call scheduler_tick() with preemption disabled - otherwise scheduler_tick()'s spin_unlock can preempt! - irqs_disabled() macro introduced. - [ all other local_irq_enable() or sti instances conditional on CONFIG_DEBUG_IRQ_SCHEDULE are to fix false positive warnings. ] Changes in -G0: - fix buggy in_softirq(). Fortunately the bug made the test broader, which didnt result in algorithmical breakage, just suboptimal performance. - move do_softirq() processing into irq_exit() => this also fixes the softirq processing bugs present in apic.c IRQ handlers that did not test for softirqs after irq_exit(). - simplify local_bh_enable(). Changes in -F9: - replace all instances of: local_save_flags(flags); local_irq_disable(); with the shorter form of: local_irq_save(flags); about 30 files are affected by this change. Changes in -F8: - preempt/hardirq/softirq count separation, cleanups. - skbuff.c fix. - use irq_count() in scheduler_tick() Changes in -F3: - the entry.S cleanups/speedups by Oleg Nesterov. - a rather critical synchronize_irq() bugfix: if a driver frees an interrupt that is still being probed then synchronize_irq() locks up. This bug has caused a spurious boot-lockup on one of my testsystems, ifconfig would lock up trying to close eth0. - remove duplicate definitions from asm-i386/system.h, this fixes compiler warnings. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/