On Mon, 16 Sep 2019, Vincent Chen wrote: > When the handle_exception function addresses an exception, the interrupts > will be unconditionally enabled after finishing the context save. However, > It may erroneously enable the interrupts if the interrupts are disabled > before entering the handle_exception. > > For example, one of the WARN_ON() condition is satisfied in the scheduling > where the interrupt is disabled and rq.lock is locked. The WARN_ON will > trigger a break exception and the handle_exception function will enable the > interrupts before entering do_trap_break function. During the procedure, if > a timer interrupt is pending, it will be taken when interrupts are enabled. > In this case, it may cause a deadlock problem if the rq.lock is locked > again in the timer ISR. > > Hence, the handle_exception() can only enable interrupts when the state of > sstatus.SPIE is 1. > > This patch is tested on HiFive Unleashed board. > > Signed-off-by: Vincent Chen <vincent.c...@sifive.com> > Reviewed-by: Palmer Dabbelt <pal...@sifive.com>
Thanks very much. Queued for v5.4-rc. - Paul
