Messages in this thread | | | Date | Tue, 22 Feb 2000 00:53:59 +0100 | From | Fabrice Bellet <> | Subject | Re: PPP is not SMP safe in 2.2.X (fix) |
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On Mon, Feb 21, 2000 at 12:05:13PM +0000, Alan Cox wrote: > > Getting a bad frame from the pty under high load is certainly legal anyway. > If your xDSL link crashes you have another problem that is bigger to worry > about,.,.
I must have misexplained myself. I mean that my xDSL link gets down due to too many bad frames, as soon as the first bad one occurs. BTW, SyncPPP is more robust.
I would accept that I could catch bad frames due to high load, but actually this only occurs in SMP, which makes me think It could be a SMP race condition.
I tracked down the bug a little deeper tonight. Frames are correctly emitted at the beginning of ppp_send_frame() [by checking their sequence number : a given frame was given to ppp_send_frame() but never arrived to the pty on the client side], but I couldn't find a way to do the same check in ppp_tty_push() : the syslog couldn't handle the debug msg rate :-) Protecting ppp_tty_push() didn't help.
I also tried to increase the output buffer size (OBUFSIZE, default to 256) so a 1500 bytes frame can fit into after control chars being escaped, and the bug vanished this way.
I also confirm that the line : kfree_sbk(ppp->tpkt); ppp->tpkt=0; at the end of ppp_async_encode() causes a oops in SMP.
Fabrice
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