On Wed, 19 Sep 2007 15:38:19 +0100 (BST) "Maciej W. Rozycki" <[EMAIL PROTECTED]> wrote:
> Keep track of disable_irq_nosync() invocations and call enable_irq() the > right number of times if work has been cancelled that would include them. > > Signed-off-by: Maciej W. Rozycki <[EMAIL PROTECTED]> > --- > Now that the call to flush_work_keventd() (problematic because of > rtnl_mutex being held) has been replaced by cancel_work_sync() another > issue has arisen and been left unresolved. As the MDIO bus cannot be > accessed from the interrupt context the PHY interrupt handler uses > disable_irq_nosync() to prevent from looping and schedules some work to be > done as a softirq, which, apart from handling the state change of the > originating PHY, is responsible for reenabling the interrupt. Now if the > interrupt line is shared by another device and a call to the softirq > handler has been cancelled, that call to enable_irq() never happens and > the other device cannot use its interrupt anymore as its stuck disabled. > > I decided to use a counter rather than a flag because there may be more > than one call to phy_change() cancelled in the queue -- a real one and a > fake one triggered by free_irq() if DEBUG_SHIRQ is used, if nothing else. > Therefore because of its nesting property enable_irq() has to be called > the right number of times to match the number disable_irq_nosync() was > called and restore the original state. This DEBUG_SHIRQ feature is also > the reason why free_irq() has to be called before cancel_work_sync(). > > While at it I updated the comment about phy_stop_interrupts() being > called from `keventd' -- this is no longer relevant as the use of > cancel_work_sync() makes such an approach unnecessary. OTOH a similar > comment referring to flush_scheduled_work() in phy_stop() still applies as > using cancel_work_sync() there would be dangerous. > > Checked with checkpatch.pl and at the run time (with and without > DEBUG_SHIRQ). You always put boring, crappy, insufficient text in the for-the-changelog section and interesting, useful, sufficient text in the not-for-the-changelog section. But you can't fool me! I have an editor and I fix it up. - 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
