On Wed, 10 Feb 2021, Song Bao Hua (Barry Song) wrote: > > On Tue, 9 Feb 2021, Song Bao Hua (Barry Song) wrote: > > > > > > > sonic_interrupt() uses an irq lock within an interrupt handler > > > > > to avoid issues relating to this. This kind of locking may be > > > > > needed in the drivers you are trying to patch. Or it might not. > > > > > Apparently, no-one has looked. > > > > > > Is the comment in sonic_interrupt() outdated according to this: > > > m68k: irq: Remove IRQF_DISABLED > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=77a4279 > > > http://lkml.iu.edu/hypermail/linux/kernel/1109.2/01687.html > > > > > > > The removal of IRQF_DISABLED isn't relevant to this driver. Commit > > 77a42796786c ("m68k: Remove deprecated IRQF_DISABLED") did not disable > > interrupts, it just removed some code to enable them. > > > > The code and comments in sonic_interrupt() are correct. You can > > confirm this for yourself quite easily using QEMU and a > > cross-compiler. > > > > > and this: genirq: Warn when handler enables interrupts > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b738a50a > > > > > > wouldn't genirq report a warning on m68k? > > > > > > > There is no warning from m68k builds. That's because > > arch_irqs_disabled() returns true when the IPL is non-zero. > > > So for m68k, the case is > arch_irqs_disabled() is true, but interrupts can still come? > > Then it seems it is very confusing. If prioritized interrupts can still > come while arch_irqs_disabled() is true, Yes, on m68k CPUs, an IRQ having a priority level higher than the present priority mask will get serviced. Non-Maskable Interrupt (NMI) is not subject to this rule and gets serviced regardless. > how could spin_lock_irqsave() block the prioritized interrupts? It raises the the mask level to 7. Again, please see arch/m68k/include/asm/irqflags.h > Isn't arch_irqs_disabled() a status reflection of irq disable API? > Why not? Are all interrupts (including NMI) masked whenever arch_irqs_disabled() returns true on your platforms? > Thanks > Barry > >
