Messages in this thread | | | Date | Mon, 21 Jul 2008 14:48:42 +0800 | From | JiSheng Zhang <> | Subject | Re: [PATCH] firewire:queue the right number of data |
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on Sun, 20 Jul 2008 16:00:32 +0200 Stefan Richter <stefanr@s5r6.in-berlin.de> wrote:
> JiSheng Zhang wrote at LKML: > > Hi, > > > > There will be 4 padding bytes in struct fw_cdev_event_response on some platforms > > The member:__u32 data will point to these padding bytes. While queue the > > response and data in complete_transaction in fw-cdev.c, it will queue like this: > > |response(excluding padding bytes)|4 padding bytes|4 padding bytes|data. > > It queue 4 extra bytes. That is to say it use "&response + sizeof(response)" > > while other place of kernel and userspace library use "&response + offsetof > > (typeof(response), data)". So it will lost the last 4 bytes of data.This patch > > can fix it while not changing the struct definition. > > > > Sorry for open a new ticket. > > > > Signed-off-by: JiSheng Zhang <jszhang3@mail.ustc.edu.cn> > > > > --- old/drivers/firewire/fw-cdev.c > > +++ new/drivers/firewire/fw-cdev.c > > @@ -382,9 +382,9 @@ > > > > response->response.type = FW_CDEV_EVENT_RESPONSE; > > response->response.rcode = rcode; > > - queue_event(client, &response->event, > > - &response->response, sizeof(response->response), > > - response->response.data, response->response.length); > > + queue_event(client, &response->event, &response->response, > > + sizeof(response->response) + response->response.length, > > + NULL, 0); > > } > > > > static int ioctl_send_request(struct client *client, void *buffer) > > I tested it now on i686, x86-64, and x86-64 with i686 userland, using > firecontrol and gscanbus. As discussed, they got corrupted block read > responses on x86-64 and on x86-64 with i686 userland. The patch fixes this. > > I committed it to linux1394-2.6.git#fixes and intend to send it upstream > at the end of the week or so. Thanks for spotting this bug. Thanks for committing. > > One point about which I am not sure about yet is what happens if there > are multiple events queued up before the client can read() them. The > tests which I did so far involved only a single event queued and > dequeued at a time. IMHO, even there are multiple events queued, it should work OK because events are put into event_list rather than a ring buffer, there is no padding bytes problem between events. > > > PS: > I removed a rule from linux1394-devel's header filters which matched > your previous posts. (Message has priority, but no X-Mailer/User-Agent) Thanks very much
Regards, JiSheng
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