On 2022/12/21 18:44, Niklas Cassel wrote: > On Wed, Dec 21, 2022 at 05:31:59PM +0900, Damien Le Moal wrote: >>> >>> What about the interrupt handler such as ahci_error_intr()? I didn't see >>> the callers hold the port lock too. Do they need the port lock? >> >> It looks like it is missing for ahci_thunderx_irq_handler() but that one >> takes the host lock. Same for xgene_ahci_irq_intr(), again no port lock >> but host lock taken. And again for ahci_single_level_irq_intr() for the >> non MSI case. For modern MSI adapters, the port lock is taken in >> >> For other cases, ahci_multi_irqs_intr_hard) takes the port lock. >> >> So it looks like ahci_port_intr() needs to take the lock and some >> cleanups overall (the host lock should not be necessary in the command >> path. But nobody seems to have issues with the "bad" cases... Probably >> because they are not mainstream adapters. >> >> Definitely some work needed here. > > ahci_multi_irqs_intr_hard() takes the ap->lock before calling > ahci_handle_port_interrupt(), which calls ahci_port_intr(), > so I don't think there is any work needed for multi IRQ AHCI. Yes. I tried to say that above. > > For ahci_single_level_irq_intr() the host lock is taken before > calling ahci_handle_port_intr(), so I don't see why we need any > extra work for single IRQ AHCI. > > > Remember, while the default is that: > ap->lock = &host->lock; Ah ! Yes ! good point ! So there are no issues anywhere. This is only confusing because of the comments I think. > see: > https://github.com/torvalds/linux/blob/v6.1/drivers/ata/libata-core.c#L5305 > > In case of MULTI MSI, the ap->lock is using its own lock: > https://github.com/torvalds/linux/blob/v6.1/drivers/ata/libahci.c#L2460 > > > So what is it that needs to be fixed for AHCI? > > I haven't looked at ahci_thunderx_irq_handler() and xgene_ahci_irq_intr() > so I can't speak for these. These are not multi-irq and use the &host->lock directly, which is the same as taking the ap->lock. We could clean that up for consistency and always use ap->lock. But not a big deal. No bugs, just a little confusing with a simple reading of the code. > > > Kind regards, > Niklas -- Damien Le Moal Western Digital Research
