On Wed, 2015-07-22 at 21:33 +0300, Eugene Shatokhin wrote: > The following part is not necessary, I think. usbnet_bh() does not > touch > EVENT_NO_RUNTIME_PM bit explicitly and these bit operations are > atomic > w.r.t. each other. > > > + mpn |= !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags); > > + /* in case the bh reset a flag */ Yes, they are atomic w.r.t. each other. And that limitation worries me. I am considering architectures which do atomic operations with spinlocks. And this code mixes another operation into it. Can this happen? CPU A CPU B take lock read old value set value to 0 clear bit write back changed value release lock Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
