Re: [PATCH v2] mtd: rework partitions handling

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

Hi Boris,

Boris Brezillon <bbrezillon@xxxxxxxxxx> wrote on Mon, 21 Jan 2019
09:51:20 +0100:

> On Wed, 16 Jan 2019 17:21:44 +0100
> Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> 
> > @@ -457,13 +525,31 @@ int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs);
> >  
> >  static inline int mtd_suspend(struct mtd_info *mtd)
> >  {
> > -	return mtd->_suspend ? mtd->_suspend(mtd) : 0;
> > +	struct mtd_info *master = mtd_get_master(mtd);
> > +	int ret;
> > +
> > +	if (master->suspended)
> > +		return 0;
> > +
> > +	ret = master->_suspend ? master->_suspend(master) : 0;
> > +	if (ret)
> > +		return ret;
> > +
> > +	master->suspended = 1;  
> 
> It's not entirely clear to me whether dev->suspend() hooks can be
> called simultaneously on several CPUs or not, if that's the case, we
> should use an atomic_t for the ->suspended field and use the
> atomic_add_unless() function when manipulating it.
> 
> 	if (!atomic_add_unless(&master->suspended, 1, 1))
> 		return 0;
> 
> 	ret = master->_suspend ? master->_suspend(master) : 0;
> 	if (ret) {
> 		atomic_dec(&master->suspended);
> 		return ret;
> 	}
> 
> > +	return 0;
> >  }
> >  
> >  static inline void mtd_resume(struct mtd_info *mtd)
> >  {
> > -	if (mtd->_resume)
> > -		mtd->_resume(mtd);
> > +	struct mtd_info *master = mtd_get_master(mtd);
> > +
> > +	if (!master->suspended)
> > +		return;
> > +
> > +	if (master->_resume)
> > +		master->_resume(master);
> > +
> > +	master->suspended = 0;  
> 
> Same here:
> 
> 	if (!atomic_add_unless(&master->suspended, -1, 0))
> 		return;
> 
> 	if (master->_resume)
> 		master->_resume(master);
> >  }  

I don't know if this is necessary but I made the changes.

I also had to change "suspended" type from unsigned int bitfield to
atomic_t.


Thanks,
Miquèl

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