Re: [PATCH] libata: Use per port sync for detach

[John Garry]

On 18/05/2020 10:06, John Garry wrote:
> On 15/05/2020 18:48, Kai-Heng Feng wrote:
> > > 841]Â ret_from_fork+0x10/0x1c
> > > [ÂÂ 28.393400] ---[ end trace 9972785c7052048f ]---
> > > [ÂÂ 28.435826] ahci 0000:b4:03.0: SSS flag set, parallel bus scan 
> > > disabled
> > Can you please test the following patch:
> >
> > diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
> > index 474c6c34fe02..51ee0cc4d414 100644
> > --- a/drivers/ata/libata-eh.c
> > +++ b/drivers/ata/libata-eh.c
> > @@ -3583,8 +3583,10 @@ int ata_eh_recover(struct ata_port *ap, 
> > ata_prereset_fn_t prereset,
> > ÂÂÂÂÂÂÂÂ rc = 0;
> > ÂÂÂÂÂÂÂÂ /* if UNLOADING, finish immediately */
> > -ÂÂÂÂÂÂ if (ap->pflags & ATA_PFLAG_UNLOADING)
> > +ÂÂÂÂÂÂ if (ap->pflags & ATA_PFLAG_UNLOADING) {
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ap->pflags |= ATA_PFLAG_UNLOADED;
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ goto out;
> > +ÂÂÂÂÂÂ }
> >
> > It's only compile-tested, many drivers panic with 
> > CONFIG_DEBUG_TEST_DRIVER_REMOVE enabled, so the system I have can't 
> > even boot properly:(

According to the comment for async_synchronize_cookie(), we sync upto 
(but excluding) the cookie:

/**
 * async_synchronize_cookie - synchronize asynchronous function calls 
with cookie checkpointing
 *
 * This function waits until all asynchronous function calls prior to 
@cookie
 * have been done.

So maybe it should be:

+	for (i = 0; i < host->n_ports; i++)
+		async_synchronize_cookie(host->ports[i]->cookie + 1);

That is how other callsites use this API, and that change resolves the 
WARN for me.

Thanks,
John