On Mon, Feb 24, 2020 at 12:44:48PM +0100, Jürgen Groß wrote: > On 24.02.20 12:25, Roger Pau Monné wrote: > > On Tue, Feb 18, 2020 at 01:21:13PM +0100, Juergen Gross wrote: > > > Some keyhandlers are calling process_pending_softirqs() while holding > > > a rcu_read_lock(). This is wrong, as process_pending_softirqs() might > > > activate rcu calls which should not happen inside a rcu_read_lock(). > > > > It might be helpful to turn the ASSERT in process_pending_softirqs > > into ASSERT_NOT_IN_ATOMIC also, as it would catch such missuses > > AFAICT. > > No, this would be triggering in __cpu_up() at system boot.
Yes, saw that in the next patch. > > > > > > > > For that purpose add process_pending_softirqs_norcu() which will not > > > do any rcu activity and use this for keyhandlers. > > > > I wonder if for keyhandlers it might be easier to just disable the > > watchdog in handle_keypress and remove the softirq processing from the > > handlers. > > > > At the end of day we want the keyhanders to run as fast as possible in > > order to get the data out, and we only care about the watchdog not > > triggering? (maybe I'm missing something here) > > It is not that simple, I believe. > > You'd need to be very careful that other functionality wouldn't suffer. > I'm e.g. not sure time_calibration won't lead to a hanging system then. AFAICT time_calibration is used to sync the timestamps of the various CPUs so that they don't drift too much, but I don't think not executing it could lead to a hang, it would lead to (bigger) skews between CPUs, but such skews happen anyway. Thanks, Roger. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
