[PATCH 2/3] lib: sbi_ipi: Process self-IPIs in sbi_ipi_send()

[Xiang W]

在 2023-12-11星期一的 15:24 +0800，Xiang W写道：
> 在 2023-12-08星期五的 13:22 -0800，Samuel Holland写道：
> > An IPI sent to the local hart can be processed directly instead of
> > triggering the IPI device. This is more efficient, and it avoids a
> > deadlock when the .sync callback is defined. Since interrupts are
> > disabled while handling an ecall, the IPI would not get delivered
> > until the next mret, but sbi_ipi_sync() is called before then.
> > 
> > Signed-off-by: Samuel Holland <samuel.holland at sifive.com>
> > ---
> > 
> >  lib/sbi/sbi_ipi.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/lib/sbi/sbi_ipi.c b/lib/sbi/sbi_ipi.c
> > index 1fd24228..ac31cd94 100644
> > --- a/lib/sbi/sbi_ipi.c
> > +++ b/lib/sbi/sbi_ipi.c
> > @@ -60,6 +60,14 @@ static int sbi_ipi_send(struct sbi_scratch *scratch, u32 remote_hartindex,
> >  				      remote_hartindex, data);
> >  		if (ret != SBI_IPI_UPDATE_SUCCESS)
> >  			return ret;
> > +	} else if (scratch == remote_scratch) {
> > +		/*
> > +		 * IPI events with an update() callback are expected to return
> > +		 * SBI_IPI_UPDATE_BREAK for self-IPIs. For other events, check
> > +		 * for self-IPI and execute the callback directly here.
> > +		 */
> > +		ipi_ops->process(scratch);
> > +		return 0;
> This modification will affect sbi_tlb.c. tlb_update has already called
> tinfo->local_fn(tinfo) when returning SBI_IPI_UPDATE_BREAK. And the 
> synchronization variable is only updated when SBI_IPI_UPDATE_SUCCESS is 
> returned. If tlb_process is called, the synchronization variable will be 
> affected.
> 
> Regards,
> Xiang W

I made a mistake! I thought ipi_ops->process(scratch) was called when 
SBI_IPI_UPDATE_BREAK was returned. I ignored that there is no ipi_ops->update
when it doesn't exist.

Look good to me.

Reviewed-by: Xiang W <wxjstz at 126.com>
> 
> >  	}
> >  
> >  	/*
> > -- 
> > 2.42.0
> > 
> > 
> 
>