Messages in this thread |  | | Date | Sun, 9 Aug 2020 12:01:38 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH 1/9] macintosh/via-macii: Access autopoll_devs when inside lock |
| |
Hi,
On Sun, Jun 28, 2020 at 02:23:12PM +1000, Finn Thain wrote: > The interrupt handler should be excluded when accessing the autopoll_devs > variable. >
I am quite baffled by this patch. Other than adding an unnecessary lock / unlock sequence, accessing a variable (which is derived from another variable) from inside or outside a lock does not make a difference. If autopoll_devs = devs & 0xfffe is 0 inside the lock, it will just as much be 0 outside the lock, and vice versa.
Can you explain this in some more detail ? Not that is matters much since the change already made it into mainline, but I would like to understand what if anything I am missing here.
Thanks, Guenter
> Fixes: d95fd5fce88f0 ("m68k: Mac II ADB fixes") # v5.0+ > Tested-by: Stan Johnson <userm57@yahoo.com> > Signed-off-by: Finn Thain <fthain@telegraphics.com.au> > --- > drivers/macintosh/via-macii.c | 9 +++------ > 1 file changed, 3 insertions(+), 6 deletions(-) > > diff --git a/drivers/macintosh/via-macii.c b/drivers/macintosh/via-macii.c > index ac824d7b2dcfc..6aa903529570d 100644 > --- a/drivers/macintosh/via-macii.c > +++ b/drivers/macintosh/via-macii.c > @@ -270,15 +270,12 @@ static int macii_autopoll(int devs) > unsigned long flags; > int err = 0; > > + local_irq_save(flags); > + > /* bit 1 == device 1, and so on. */ > autopoll_devs = devs & 0xFFFE; > > - if (!autopoll_devs) > - return 0; > - > - local_irq_save(flags); > - > - if (current_req == NULL) { > + if (autopoll_devs && !current_req) { > /* Send a Talk Reg 0. The controller will repeatedly transmit > * this as long as it is idle. > */
|  |