Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753969Ab1EDLpm (ORCPT ); Wed, 4 May 2011 07:45:42 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:38462 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753777Ab1EDLpl (ORCPT ); Wed, 4 May 2011 07:45:41 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Date: Wed, 4 May 2011 13:45:20 +0200 From: Stefan Richter To: Linus Torvalds , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux1394-devel@lists.sourceforge.net Subject: [git pull] FireWire regression fix Message-ID: <20110504134520.0a0aa35e@stein> X-Mailer: Claws Mail 3.7.8 (GTK+ 2.22.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4703 Lines: 129 Linus, please pull from the fixes branch at git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6.git fixes to receive the following update for the IEEE 1394 (FireWire) subsystem. Thanks. B.J. Buchalter (1): firewire: Fix for broken configrom updates in quick succession drivers/firewire/ohci.c | 39 +++++++++++++++++++++++++-------------- 1 files changed, 25 insertions(+), 14 deletions(-) commit 2e053a27d9d5ad5e0831e002cbf8043836fb2060 Author: B.J. Buchalter Date: Mon May 2 13:33:42 2011 -0400 firewire: Fix for broken configrom updates in quick succession Current implementation of ohci_set_config_rom() uses a deferred bus reset via fw_schedule_bus_reset(). If clients add multiple unit descriptors to the config_rom in quick succession, the deferred bus reset may not have fired before succeeding update requests have come in. This can lead to an incorrect partial update of the config_rom for both addition and removal of config_rom descriptors, as the ohci_set_config_rom() routine will return -EBUSY if a previous pending update has not been completed yet; the requested update just gets dropped on the floor. This patch recognizes that the "in-flight" update can be modified until it has been processed by the bus-reset, and the locking in the bus_reset_tasklet ensures that the update is done atomically with respect to modifications made by ohci_set_config_rom(). The -EBUSY error case is simply removed. [Stefan R: The bug always existed at least theoretically. But it became easy to trigger since 2.6.36 commit 02d37bed188c "firewire: core: integrate software-forced bus resets with bus management" which introduced long mandatory delays between janitorial bus resets.] Signed-off-by: Benjamin Buchalter Signed-off-by: Stefan Richter (trivial style changes) Cc: # 2.6.36.y and newer diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index f903d7b6..23d1468 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -2199,7 +2199,6 @@ static int ohci_set_config_rom(struct fw_card *card, { struct fw_ohci *ohci; unsigned long flags; - int ret = -EBUSY; __be32 *next_config_rom; dma_addr_t uninitialized_var(next_config_rom_bus); @@ -2240,22 +2239,37 @@ static int ohci_set_config_rom(struct fw_card *card, spin_lock_irqsave(&ohci->lock, flags); + /* + * If there is not an already pending config_rom update, + * push our new allocation into the ohci->next_config_rom + * and then mark the local variable as null so that we + * won't deallocate the new buffer. + * + * OTOH, if there is a pending config_rom update, just + * use that buffer with the new config_rom data, and + * let this routine free the unused DMA allocation. + */ + if (ohci->next_config_rom == NULL) { ohci->next_config_rom = next_config_rom; ohci->next_config_rom_bus = next_config_rom_bus; + next_config_rom = NULL; + } - copy_config_rom(ohci->next_config_rom, config_rom, length); + copy_config_rom(ohci->next_config_rom, config_rom, length); - ohci->next_header = config_rom[0]; - ohci->next_config_rom[0] = 0; + ohci->next_header = config_rom[0]; + ohci->next_config_rom[0] = 0; - reg_write(ohci, OHCI1394_ConfigROMmap, - ohci->next_config_rom_bus); - ret = 0; - } + reg_write(ohci, OHCI1394_ConfigROMmap, ohci->next_config_rom_bus); spin_unlock_irqrestore(&ohci->lock, flags); + /* If we didn't use the DMA allocation, delete it. */ + if (next_config_rom != NULL) + dma_free_coherent(ohci->card.device, CONFIG_ROM_SIZE, + next_config_rom, next_config_rom_bus); + /* * Now initiate a bus reset to have the changes take * effect. We clean up the old config rom memory and DMA @@ -2263,13 +2277,10 @@ static int ohci_set_config_rom(struct fw_card *card, * controller could need to access it before the bus reset * takes effect. */ - if (ret == 0) - fw_schedule_bus_reset(&ohci->card, true, true); - else - dma_free_coherent(ohci->card.device, CONFIG_ROM_SIZE, - next_config_rom, next_config_rom_bus); - return ret; + fw_schedule_bus_reset(&ohci->card, true, true); + + return 0; } static void ohci_send_request(struct fw_card *card, struct fw_packet *packet) -- Stefan Richter -=====-==-== -=-= --=-- http://arcgraph.de/sr/ -- 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/