Messages in this thread Patch in this message | | | Date | Tue, 17 Jun 2008 20:13:23 +0200 (CEST) | From | Stefan Richter <> | Subject | [RFT patch, regression fix] firewire: deadline for PHY config transmission |
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If the low-level driver failed to initialize a card properly without noticing it, fw-core was blocked indefinitely when trying to send a PHY config packet. This hung up the events kernel thread, e.g. locked up keyboard input. https://bugzilla.redhat.com/show_bug.cgi?id=444694 https://bugzilla.redhat.com/show_bug.cgi?id=446763
This problem was introduced between 2.6.25 and 2.6.26-rc1 by commit 2a0a2590498be7b92e3e76409c9b8ee722e23c8f "firewire: wait until PHY configuration packet was transmitted (fix bus reset loop)".
The proposed solution is to wait with timeout. Another potential and lower-tech solution would be to wait for a fixed period (which has to be long enough to guarantee that the PHY config packet was transmitted before the bus manager code proceeds to reset the bus).
I briefly tested the patch with 7 different working controllers and the packet callback seems to complete() always before the arbitrarily chosen timeout of 10ms plus rounding.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> ---
This patch has yet to be tested by the Fedora bug reporters whether it fixes the issue at all.
drivers/firewire/fw-transaction.c | 47 +++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 14 deletions(-)
Index: linux/drivers/firewire/fw-transaction.c =================================================================== --- linux.orig/drivers/firewire/fw-transaction.c +++ linux/drivers/firewire/fw-transaction.c @@ -20,6 +20,7 @@ #include <linux/completion.h> #include <linux/kernel.h> +#include <linux/kref.h> #include <linux/module.h> #include <linux/init.h> #include <linux/interrupt.h> @@ -300,37 +301,55 @@ EXPORT_SYMBOL(fw_send_request); struct fw_phy_packet { struct fw_packet packet; struct completion done; + struct kref kref; }; -static void -transmit_phy_packet_callback(struct fw_packet *packet, - struct fw_card *card, int status) +static void phy_packet_release(struct kref *kref) +{ + struct fw_phy_packet *p = + container_of(kref, struct fw_phy_packet, kref); + kfree(p); +} + +static void transmit_phy_packet_callback(struct fw_packet *packet, + struct fw_card *card, int status) { struct fw_phy_packet *p = container_of(packet, struct fw_phy_packet, packet); complete(&p->done); + kref_put(&p->kref, phy_packet_release); } void fw_send_phy_config(struct fw_card *card, int node_id, int generation, int gap_count) { - struct fw_phy_packet p; + struct fw_phy_packet *p; + long timeout = DIV_ROUND_UP(HZ, 100); u32 data = PHY_IDENTIFIER(PHY_PACKET_CONFIG) | PHY_CONFIG_ROOT_ID(node_id) | PHY_CONFIG_GAP_COUNT(gap_count); - p.packet.header[0] = data; - p.packet.header[1] = ~data; - p.packet.header_length = 8; - p.packet.payload_length = 0; - p.packet.speed = SCODE_100; - p.packet.generation = generation; - p.packet.callback = transmit_phy_packet_callback; - init_completion(&p.done); + p = kmalloc(sizeof(*p), GFP_KERNEL); + if (p == NULL) + return; + + p->packet.header[0] = data; + p->packet.header[1] = ~data; + p->packet.header_length = 8; + p->packet.payload_length = 0; + p->packet.speed = SCODE_100; + p->packet.generation = generation; + p->packet.callback = transmit_phy_packet_callback; + init_completion(&p->done); + kref_set(&p->kref, 2); + + card->driver->send_request(card, &p->packet); + timeout = wait_for_completion_timeout(&p->done, timeout); + kref_put(&p->kref, phy_packet_release); - card->driver->send_request(card, &p.packet); - wait_for_completion(&p.done); + /* will leak p if the callback is never executed */ + WARN_ON(timeout == 0); } void fw_flush_transactions(struct fw_card *card) -- Stefan Richter -=====-==--- -==- =---= http://arcgraph.de/sr/
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