Jeff Garzik wrote: > Chris Lalancette wrote: > >> Francois Romieu wrote: >> >>> Chris Lalancette <[EMAIL PROTECTED]> : >>> [...] >>> >>> >>>> Thanks for the comments. While the patch you sent will help, >>>> there are >>>> still other places that will have problems. For example, in >>>> netpoll_send_skb, >>>> we call local_irq_save(flags), then call dev->hard_start_xmit(), >>>> and then call >>>> local_irq_restore(flags). This is a similar situation to what I >>>> described >>>> above; we will re-enable interrupts in cp_start_xmit(), when >>>> netpoll_send_skb >>>> doesn't expect that, and will probably run into issues. >>>> Is there a problem with changing cp_start_xmit to use the >>>> spin_lock_irqsave(), besides the extra instructions it needs? >>>> >>> >>> No. Given the history of locking in netpoll and the content of >>> Documentation/networking/netdevices.txt, asking Herbert which rule(s) >>> the code is supposed to follow seemed safer to me. >>> >>> You can forget my patch. >>> >>> Please resend your patch inlined to Jeff as described in >>> http://linux.yyz.us/patch-format.html. >>> >>> >>> >> Francois, >> Great. Resending mail, shortening subject to < 65 characters and >> inlining the patch. >> >> Thanks, >> Chris Lalancette >> >> Similar to this commit: >> >> http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=d15e9c4d9a75702b30e00cdf95c71c88e3f3f51e >> >> >> It's not safe in cp_start_xmit to blindly call spin_lock_irq and then >> spin_unlock_irq, since it may very well be the case that cp_start_xmit >> was called with interrupts already disabled (I came across this bug in >> the context of netdump in RedHat kernels, but the same issue holds, for >> example, in netconsole). Therefore, replace all instances of >> spin_lock_irq and spin_unlock_irq with spin_lock_irqsave and >> spin_unlock_irqrestore, respectively, in cp_start_xmit(). I tested this >> against a fully-virtualized Xen guest using netdump, which happens to >> use the 8139cp driver to talk to the emulated hardware. I don't have a >> real piece of 8139cp hardware to test on, so someone else will have to >> do that. >> >> Signed-off-by: Chris Lalancette <[EMAIL PROTECTED]> > > > applied. > > In the future, please remove the quoted emails stuff, and anything > else that does not belong in the kernel changelog. It must be > hand-edited out, before using git-am to merge your patch into the > kernel tree. > > Jeff > > > Jeff, Ah, I see. Noted. Thanks.
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