> -----Original Message----- > From: Finn Thain [mailto:fthain@xxxxxxxxxxxxxxxxxxx] > Sent: Wednesday, February 10, 2021 5:16 PM > To: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx> > Cc: tanxiaofei <tanxiaofei@xxxxxxxxxx>; jejb@xxxxxxxxxxxxx; > martin.petersen@xxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; linuxarm@xxxxxxxxxxxxx; > linux-m68k@xxxxxxxxxxxxxxx > Subject: [Linuxarm] Re: [PATCH for-next 00/32] spin lock usage optimization > for SCSI drivers > > 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 Is the comment in sonic_interrupt() outdated according to this: 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, how could spin_lock_irqsave() block the prioritized interrupts? Isn't arch_irqs_disabled() a status reflection of irq disable API? Thanks Barry
