On Tue, May 8, 2018 at 10:55 AM, Daniel Wagner <[email protected]> wrote: > From: Daniel Wagner <[email protected]> > > Commit 40f70c03e33a ("serial: sh-sci: add locking to console write > function to avoid SMP lockup") copied the strategy to avoid locking > problems in conjuncture with the console from the UART8250 > driver. Instead using directly spin_{try}lock_irqsave(), > local_irq_save() followed by spin_{try}lock() was used. While this is > correct on mainline, for -rt it is a problem. spin_{try}lock() will > check if it is running in a valid context. Since the local_irq_save() > has already been executed, the context has changed and > spin_{try}lock() will complain. The reason why spin_{try}lock() > complains is that on -rt the spin locks are turned into mutexes and > therefore can sleep. Sleeping with interrupts disabled is not valid.
[...] > Cc: Geert Uytterhoeven <[email protected]> > Cc: Sebastian Andrzej Siewior <[email protected]> > Signed-off-by: Daniel Wagner <[email protected]> > --- > changes since v2: > - dropped the local_irq_save() it's wrong as Sebastian pointed out > > changes since v1: > - Ported to current mainline (initial version was against v4.4.y) > - Left local_irq_save() in place when spinlocks are not used as suggested > by Geert. Thanks for the update! Reviewed-by: Geert Uytterhoeven <[email protected]> Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected] In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
