Re: FW: ccid2/ccid3 oopses
Roland, -
apparently, i got crashes when loading/unloading other driver modules just
after ccid2 or ccid3 had been loaded/unloaded _once_ (have not used them at
all, just modprobe module;modprobe -r module)
snip
the easiest way to reproduce is:
while true;do modprobe dccp_ccid2/3;modprobe -r dccp_ccid2/3;done
after short time, the kernel oopses (messages below)
i`m not sure if this is worth to be filed at kernel bugzilla, so i`m
contacting
you personally first.
The issue is known: once loaded, the DCCP modules can not be unloaded
without causing a crash as the one you have observed. This is due to the
fact that dccp_ipv{4,6} use control sockets which need to be released
before the module can be unloaded.
When the control sockets are not released then crashes will always
result.
In earlier versions of DCCP there was a kernel option known as unload hack,
which conditionally inserted
sock_release(dccp_v{4,6}_ctl_socket);
in
dccp_v{4,6}_exit()
However, as the name says, it is a hack since there are other issues to
be considered:
* sockets in timewait state
* other wait states (e.g. half-open connections)
* memory which has not been released
* module dependencies
With regard to the latter, I am normally using the Unload Hack and
release modules in the following order:
dccp_probe = dccp_ccid2 = dccp_ccid3 = dccp_tfrc_lib =
dccp_ipv6 = dccp_ipv4 = dccp_diag = dccp
Long story short
* the CCID/DCCP modules can currently not safely be unloaded
* maybe we should disable module unloading for the mainline kernel
* if anyone is interested to use the unload hack, here is the old patch
http://www.erg.abdn.ac.uk/users/gerrit/dccp/testing_dccp/Unload_Hack.diff
Please feel free to come back on this issue
Gerrit
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Re: FW: ccid2/ccid3 oopses
Em Wed, Jan 09, 2008 at 12:28:27PM +, Gerrit Renker escreveu:
Roland, -
apparently, i got crashes when loading/unloading other driver modules just
after ccid2 or ccid3 had been loaded/unloaded _once_ (have not used them at
all, just modprobe module;modprobe -r module)
snip
the easiest way to reproduce is:
while true;do modprobe dccp_ccid2/3;modprobe -r dccp_ccid2/3;done
after short time, the kernel oopses (messages below)
i`m not sure if this is worth to be filed at kernel bugzilla, so i`m
contacting
you personally first.
The issue is known: once loaded, the DCCP modules can not be unloaded
without causing a crash as the one you have observed. This is due to the
fact that dccp_ipv{4,6} use control sockets which need to be released
before the module can be unloaded.
When the control sockets are not released then crashes will always
result.
In earlier versions of DCCP there was a kernel option known as unload hack,
which conditionally inserted
sock_release(dccp_v{4,6}_ctl_socket);
in
dccp_v{4,6}_exit()
However, as the name says, it is a hack since there are other issues to
be considered:
* sockets in timewait state
* other wait states (e.g. half-open connections)
* memory which has not been released
* module dependencies
With regard to the latter, I am normally using the Unload Hack and
release modules in the following order:
dccp_probe = dccp_ccid2 = dccp_ccid3 = dccp_tfrc_lib =
dccp_ipv6 = dccp_ipv4 = dccp_diag = dccp
Long story short
* the CCID/DCCP modules can currently not safely be unloaded
* maybe we should disable module unloading for the mainline kernel
* if anyone is interested to use the unload hack, here is the old patch
http://www.erg.abdn.ac.uk/users/gerrit/dccp/testing_dccp/Unload_Hack.diff
Gerrit, the control socket isn't attached to any CCID module, so the
CCID modules should be safe to remove, and IIRC they were safe to
unload.
The unload hack was for something else, for the core DCCP modules. We
can't unload because there are refcounts held by the control sock, so
the unload hack would just destroy the control sock and thus the module
refcount would reach zero and it could then be unloaded.
I've been consistently being sidetracked with work (huh :-)) and
couldn't look at this issue, but the CCID modules should be safe to
unload.
- Arnaldo
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Re: FW: ccid2/ccid3 oopses
| the easiest way to reproduce is: | | while true;do modprobe dccp_ccid2/3;modprobe -r dccp_ccid2/3;done | after short time, the kernel oopses (messages below) | snip | | Gerrit, the control socket isn't attached to any CCID module, so the | CCID modules should be safe to remove, and IIRC they were safe to | unload. | Ah, right. I have misread the email. And can confirm the above: running the for-loop at the top of the message (60 seconds uninterrupted for CCID2,3 each) brought no oopses. So maybe the cause triggering this oops is somewhere else. - To unsubscribe from this list: send the line unsubscribe dccp in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [dccp] question about CCID3
Zhao, Have you tried working with 2.6.20 (along with Ian's patches)? I recall having similar problems with versions other than 2.6.20. Also getting Gerrit's latest tree should fix your problems. BTW, DCCP Linux Implementation mailing list, which is included in Cc, is a better place to post such mails. BR -- Burak - Original Message From: jerry zhao [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, January 9, 2008 5:36:18 PM Subject: RE: [dccp] question about CCID3 You are probably behind a firewall. B.R. Vladimir. Hello Vladimir., thanks for your reply. I don't think firewall is the reason. Because I have tested the performance of DCCP when ccid2 was used. In this situation, the DCCP worked fine. Now, I attached the result of CCID2 to the attachment. Best regards, Zhao - To unsubscribe from this list: send the line unsubscribe dccp in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
