On Thu, 18 Oct 2007, Maciej W. Rozycki wrote: > > 1) phy_change() checks PHY_HALTED flag without lock; I think it's > > racy: eg. if it's done during phy_stop() it can check just before > > the flag is set and reenable interrupts just after phy_stop() ends. > > I remember having a look into it, but it was long ago and I cannot > immediately recall the conclusion. Which means it is either broken or > deserves a comment as non-obvious. I will have a look into it again, but > I am resource-starved a little at the moment, sorry.
Well, I have now recalled what the issue is -- we just plainly and simply want to avoid a hardirq spinlock for the very reason we do not do all the processing in the hardirq handler. The thing is we make accesses to the MDIO bus with the phydev lock held and it may take ages until these accesses will have completed. And we cannot afford keeping interrupts disabled for so long. So the only way is to make the check for the HALTED state lockless and make sure any race condition is handled gracefully and does not lead to inconsistent behaviour. Which I think as of what we have in the net-2.6.24 tree is the case, but there are never too many eyes to look at a piece of code, so if anybody feels like proving me wrong, then just go ahead! Maciej - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
