On Mon, 02 May 2022 12:28:29 +0100, Thomas Pfaff <tpfaff@xxxxxxx> wrote: > > From: Thomas Pfaff <tpfaff@xxxxxxx> > > While running > "while /bin/true; do setserial /dev/ttyS0 uart none; > setserial /dev/ttyS0 uart 16550A; done" > on a kernel with threaded irqs, setserial is hung after some calls. > > setserial opens the device, this will install an irq handler if the uart is > not none, followed by TIOCGSERIAL and TIOCSSERIAL ioctls. > Then the device is closed. On close, synchronize_irq() is called by > serial_core. > > If the close comes too fast, the irq_thread does not really start, > it is terminated immediately without going into irq_thread(). > But an interrupt might already been handled by > irq_default_primary_handler(), going to __irq_wake_thread() and > incrementing threads_active. > If this happens, synchronize_irq() will hang forever, because the > irq_thread is already dead, and threads_active will never be decremented. > > The fix is to make sure that the irq_thread is really started > during __setup_irq(). > > Signed-off-by: Thomas Pfaff <tpfaff@xxxxxxx> Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx> M. -- Without deviation from the norm, progress is not possible.
