From owner-freebsd-current@FreeBSD.ORG Fri May 4 19:58:24 2007 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 28A4B16A415 for ; Fri, 4 May 2007 19:58:24 +0000 (UTC) (envelope-from asmrookie@gmail.com) Received: from ik-out-1112.google.com (ik-out-1112.google.com [66.249.90.178]) by mx1.freebsd.org (Postfix) with ESMTP id A39CD13C4CB for ; Fri, 4 May 2007 19:58:23 +0000 (UTC) (envelope-from asmrookie@gmail.com) Received: by ik-out-1112.google.com with SMTP id b35so943213ika for ; Fri, 04 May 2007 12:58:22 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:reply-to:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding:sender; b=dtJUr/RrdtyxEHMN4tl961U7zHySi0HT12ElyTYv6pijeln2H1ZCJhuD8XUU7NGv3bspzfeYbt4/oorCPaCewGZuLqAZ/CVzGTifm43c5vrgnpdq/KTtVjIHIlnNdrbjGwRmxaletx3NcSVHzzjBqAfHkqGVvY5JTZAiw68j0xw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:reply-to:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding:sender; b=YoVudmiPDSe23eIFmhAWvsqxt35pP+aHufCfHASaXzaIHJUWZADUGH3GO3I3k9EcA7ssssOQ8mpnmiBiT04ozAuc8DP+48dX6KxqO1gQpOEn1iU8a4qEbQy228Qh6RKNXQD2UzqqlEdjLLQMEhCr2+zXOWZNOsBwtDb1ggmE/C4= Received: by 10.82.148.7 with SMTP id v7mr7217508bud.1178308702132; Fri, 04 May 2007 12:58:22 -0700 (PDT) Received: from ?151.75.229.145? ( [151.75.229.145]) by mx.google.com with ESMTP id b36sm1177082ika.2007.05.04.12.58.20; Fri, 04 May 2007 12:58:21 -0700 (PDT) Message-ID: <463C01B4.9050802@FreeBSD.org> Date: Sat, 05 May 2007 06:01:56 +0200 From: Attilio Rao User-Agent: Thunderbird 1.5 (X11/20060526) MIME-Version: 1.0 To: John Baldwin References: <463B7A1D.6020602@omnisec.de> <463BF1A7.1050504@FreeBSD.org> <200705041546.50690.jhb@freebsd.org> In-Reply-To: <200705041546.50690.jhb@freebsd.org> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: Attilio Rao Cc: freebsd-current@freebsd.org, Harald Schmalzbauer Subject: Re: PANIC: blockable slep lock (sx) msi @ ....msi.c:374 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: attilio@FreeBSD.org List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 May 2007 19:58:24 -0000 John Baldwin wrote: > On Friday 04 May 2007 10:53:27 pm Attilio Rao wrote: >> Harald Schmalzbauer wrote: >>> Hello, >>> >>> recent changes (during the last 2 days,I guess tha acpi stuff) broke >>> -current for me: >>> >>> ad6: 476940MB at ata3-master SATA300 >>> SMP: AP CPU #1 Launched! >>> panic: blockable sleep lock (sx) msi @ >>> /FlashBSD/src/sys/i386/i386/msi.c:374 >>> cpuid = 0 >>> KDB: enter: panic >>> [thread pid 0 tid 0 ] >>> Stopped at kdb_enter+0x30: leave >>> db> bt >>> Tracing pid 0 tid 0 td 0xc07c2d60 >>> kdb_enter(c07422df,0,c0746e47,c1420bdc,c07c2d60,...) at kdb_enter+0x30 >>> panic(c0746e47,c073180d,c0732bb2,c0764c8e,176,...) at panic+0x135 >>> witness_checkorder(c082f0fc,1,c0764c8e,176,c55c0980,...) at >>> witness_checkorder+0xd6 >>> _sx_slock(c082f0fc,c0764c8e,176,c1420c64,c06f7e65,...) at _sx_slock+0x5f >>> msi_map(100,c1420d08,c1420d04,c1420c94,c04b5cc5,...) at msi_map+0x22 >>> nexus_map_msi(c5552000,c55e4000,100,c1420d08,c1420d04,...) at >>> nexus_map_msi+0x1f >>> pcib_map_msi(c55d9080,c55e4000,100,c1420d08,c1420d04,...) at >>> pcib_map_msi+0x86 >>> pcib_map_msi(c55e4200,c55e4000,100,c1420d08,c1420d04,...) at >>> pcib_map_msi+0x86 >>> pci_remap_msi_irq(c55e4000,100,c06ecb73,c54fff78,100,...) at >>> pci_remap_msi_irq+0xeb >>> msi_assign_cpu(c55e6240,0,100,c079d170,c1420d70,...) at > msi_assign_cpu+0x68 >>> intr_assign_next_cpu(c55e6240,0,c07631d3,1c7,c54f3a44,...) at >>> intr_assign_next_cpu+0x23 >>> intr_shuffle_irqs(0,141e000,141ec00,141e000,0,...) at >>> intr_shuffle_irqs+0x5e >>> mi_startup() at mi_startup+0xa0 >>> begin() at begin+0x2c >> In this case the culprit is intr_table_lock spinlock I think. >> This can be fixed switching the msi lock to be a spinlock instead than a >> sx lock. > > Actually, I think the real fix is I need to better handle the locking for > assigning interrupts to CPUs. I have a question. Why you currently use a sx lock? There are places where msi functions can sleep? >> However I wonder, it is right to let sleepable lock to arise a WITNESS >> exception if the lock is acquired in a critical section? >> I can understand this is a simple way to detect if a spinlock has been >> previously called, but this leads to the 'false positive' case in which >> we can have something like: >> >> critical_enter(); >> sx_xlock(&lock1); >> etc.etc. > > This is wrong because once you do critical_enter(), you are free to assume > that you won't do a context switch until you critical_exit(), and sx_xlock() > would violate that if it blocked on the lock. Yes, this is right. Attilio