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Message-ID: <tkrat.230a7a03785f244f@s5r6.in-berlin.de>
Date: Tue, 17 Jun 2008 20:13:23 +0200 (CEST)
From: Stefan Richter <stefanr@...6.in-berlin.de>
To: linux1394-devel@...ts.sourceforge.net
cc: linux-kernel@...r.kernel.org
Subject: [RFT patch, regression fix] firewire: deadline for PHY config
transmission
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@...6.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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